Limbal Stem Cell Transplantation for Soft Contact Lens Wear–Related Limbal Stem Cell Deficiency CARL SHEN, CLARA C. CHAN, AND EDWARD J. HOLLAND PURPOSE:
To describe the outcomes of limbal stem cell transplantation in eyes with limbal stem cell deficiency related to soft contact lens wear. DESIGN: Retrospective interventional case series. METHODS: Institutional database search at the Cincinnati Eye Institute revealed 9 patients (14 eyes) who underwent limbal stem cell transplantation with systemic immunosuppression for soft contact lens wear–related limbal stem cell deficiency. Outcome measures included patient demographics, symptoms, best-corrected visual acuity, ocular surface stability, adverse events, and additional surgeries required. RESULTS: Average patient age at time of surgery was 46.6 ± 11.1 years (range 20–60 years). Average duration of follow-up was 28 ± 19.1 months (range 12– 70 months). Preoperative best-corrected visual acuity (BCVA) was 20/40 or worse in all eyes (average 20/70, range 20/40–20/250) and patient symptoms included foreign body sensation, tearing, redness, and/or pain. Four eyes (29%) underwent living-related conjunctival limbal allograft and 10 eyes (71%) underwent cadaverdonor keratolimbal allograft surgery. Topical and systemic immunosuppression was used in all patients. At final follow-up after limbal stem cell transplantation, there was a stable ocular surface in 12 of 14 eyes (86%) and improvement in BCVA to 20/30 or better and complete resolution of patient symptoms in all except 1 patient who had significant rosacea blepharokeratoconjunctivitis, whose BCVA remained at 20/150 and 20/60, in right and left eyes, respectively. The most common adverse event was an increase in intraocular pressure in 8 of 14 eyes (57%), requiring topical antiglaucoma treatment. Ten of 14 eyes (71%) underwent cataract extraction related to topical steroid use. No eyes required subsequent penetrating keratoplasty.
Accepted for publication Jul 31, 2015. From the University of Toronto Medical School, Toronto, Canada (C.S.); and Cincinnati Eye Institute, Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio (C.C.C., E.J.H.). Dr Clara C. Chan is now on faculty at the Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada. Inquiries to Clara C. Chan, Department of Ophthalmology and Vision Sciences, University of Toronto, 600 Sherbourne St, Suite 601, Toronto, Ontario M4X1W4, Canada; e-mail: [email protected]
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2015 BY
CONCLUSION:
Limbal stem cell transplantation is a viable option for the management of soft contact lens wear–related limbal stem cell deficiency in young healthy patients. Early intervention prior to subepithelial fibrosis can lead to good visual outcomes with no need for subsequent cornea transplant. Co-management with a solid organ transplant specialist is helpful for the monitoring and management of systemic adverse events related to patient systemic immunosuppression. (Am J Ophthalmol 2015;160(6):1142–1149. Ó 2015 by Elsevier Inc. All rights reserved.)
L
IMBAL STEM CELLS ARE REQUIRED FOR THE MAINTE-
nance of a stable corneal epithelial surface and act as a barrier to any conjunctivalization of the cornea.1,2 The loss or dysfunction of the limbal stem cells results in limbal stem cell deficiency. Clinically, this manifests as persistent epithelial defects, corneal conjunctivalization, corneal scarring, chronic inflammation, vision loss, chronic pain, photophobia, and keratoplasty failure.3 On examination, the epithelium may appear opaque, and/or a classic pattern of late fluorescein corneal staining occurs (Figure) because of the increased permeability of abnormal epithelial cells.4 In addition, migrating conjunctival goblet cells can be detected on the corneal surface by impression cytology.5 Numerous causes of limbal stem cell deficiency exist, including aniridia, chemical injury, burns, radiation, Stevens-Johnson syndrome, contact lens wear, and cicatricial pemphigoid, among others. Limbal stem cell deficiency can be staged according to amount of limbal involvement and the inflammatory status of the conjunctiva.6 Severe limbal stem cell deficiency is a rare complication of contact lens wear that has been associated with female sex and extended duration of wear time.7 It is classified as stage AII by a loss of limbal stem cells greater than 6 clock hours (near total) up to 12 clock hours (total). In less severe or partial contact lens wear–related limbal stem cell deficiency (stage AI), patients can be managed with conservative treatment consisting of the discontinuation of contact lens wear, management of dry eye and blepharitis, epithelial debridement and amniotic membrane graft, and/or sequential epithelial debridement.8 However, in severe contact lens wear–related limbal stem cell deficiency, limbal stem cell transplantation is required for restoration
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0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2015.07.038
FIGURE. Photograph of severe limbal stem cell deficiency in the right eye of Patient 3. (Top left) Note the abnormal opaque epithelium arising from the superior limbus and extending into the visual axis. (Top right) Note the whorl-like epitheliopathy with classic late fluorescein staining pattern superiorly and inferiorly, and through the visual axis. (Bottom left) Five months later, there is progression of the patient’s disease with total surface late fluorescein staining and corneal erosion causing reduced vision to 20/200. (Bottom right) Twenty-one months after undergoing living-related conjunctival limbal allograft from donor brother. Note the smooth corneal epithelium with clear corneal light reflex.
of the corneal phenotype. Keratolimbal allograft and living-related conjunctival limbal allograft are 2 techniques for transplanting allogenic tissue containing limbal stem cells into a recipient eye. The purpose of this study was to describe the outcomes of limbal stem cell transplantation by keratolimbal allograft and living-related conjunctival limbal allograft in the treatment of severe contact lens wear–related limbal stem cell deficiency.
corrected visual acuity (BCVA), type of limbal stem cell transplant, ocular surface stability, adverse events, and additional surgeries required. A stable ocular surface was defined as an intact corneal epithelium and absence of corneal conjunctivalization and conjunctival inflammation. An improved ocular surface was defined as a partial failure with areas of healthy cornea and areas of abnormal conjunctival epithelium. SURGICAL
METHODS THIS RETROSPECTIVE STUDY WAS REVIEWED BY THE ST ELIZ-
abeth’s Health Care (Edgewood, Kentucky) Institutional Review Board (IRB # 4/2011-009) and determined to be exempt. This study was conducted in compliance with the tenets of the Declaration of Helsinki. PATIENTS: A database search of patients with a diagnosis of severe limbal stem cell deficiency related to contact lens wear was conducted at a single institution. The charts of 18 eyes from 12 patients were identified. Of those, 14 eyes from 9 patients had undergone limbal stem cell transplantation and their charts were retrospectively reviewed. Outcome measures that were analyzed consisted of patient demographics, presenting symptoms, change in best-
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PROCEDURES: Keratolimbal allograft. The protocol for tissue procurement and preparation was followed, and this surgical technique has been described previously.9 Briefiy, paired corneoscleral rims were used as the source for transplanted limbal stem cells. The central cornea was excised with a 7.5 mm trephine. The remaining corneoscleral rim was sectioned into 2 equal halves, and excess peripheral scleral tissue was trimmed. The posterior one half to two thirds of each hemisection was removed via lamellar dissection using a steel crescent blade and then discarded. A 360-degree limbal peritomy was performed on the recipient eye. The conjunctiva was resected for 4–5 mm to expose an adequate area of sclera on which to position the allograft tissue. Abnormal fibrovascular pannus and epithelium were removed from the cornea with a combination of sharp and blunt dissection. Three of the 4 dissected crescents were placed on the recipient eye with the donor corneal edge
LIMBAL STEM CELL TRANSPLANTATION IN CONTACT LENS WEAR LSCD
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overlying the recipient limbus secured with 10-0 nylon interrupted buried sutures and with tissue glue for the base. The recipient conjunctival edge was ensured to abut the posterior edge of the transplanted tissue.
cording to the degree of conjunctival inflammation. Valganciclovir 225 mg daily for 1 year (discontinued if CMV IgG negative) and sulfamethoxazole and trimethoprim 1 tablet 3 times weekly were given as prophylaxis.
Living-related conjunctival limbal allograft. The protocol for tissue procurement and preparation was followed, and this surgical technique has been described previously.10 Briefly, the best match from potential donors was identified from immediate relatives based on human leukocyte antigen and ABO blood typing. Donors were assessed preoperatively for transmissible diseases and to ensure there were no ocular pathologic conditions present. The nondominant eye was selected as the donor. In the donor eye, 3 clock hours of limbal conjunctival tissue at the 12- and 6-o’clock positions were marked with a gentian violet blue marker and resected 3–4 mm posteriorly. Conjunctival tissue, including the Vogt palisades, was dissected 1 mm anteriorly onto the corneal surface. Vannas scissors were then used to cut the conjunctiva from the cornea. The 2 pieces of donor tissue were floated on balanced salt solution (Alcon, Fort Worth, Texas, USA) and transferred for transplantation to the recipient. The conjunctival wounds were then closed 1 mm posterior to the limbus using 10-0 vicryl sutures (Ethicon, Johnson & Johnson, Cincinnati, OH). Subconjunctival injections of ancef and dexamethasone were given. A topical-fourth generation fluoroquinolone was applied and the eye was patched. In the recipient, a conjunctival peritomy was performed at the 12- and 6-o’clock positions, and limbal conjunctiva was undermined and allowed to retract posteriorly. Removal of pannus and irregular epithelium was performed by debridement and careful dissection using a 64 blade. The conjunctival-limbal grafts were secured at the limbus using 10-0 nylon sutures and at the base with tissue glue. Subconjunctival injections of cefazolin and dexamethasone were administered. A large-diameter contact lens was placed and a patch applied.
STATISTICAL ANALYSIS:
IMMUNOSUPPRESSION REGIMEN:
All patients received an immunosuppression regimen as previously described.11 In brief, postoperatively, patients were given topical cyclosporine 0.05% 2 times daily and prednisolone acetate or difluprednate 1% 4 times daily. Topical steroid was maintained at 4 times daily for the first 3 months and then decreased by 1 drop per month. Patients were then maintained on topical steroids at least once daily according to the degree of conjunctival inflammation. Systemic immunosuppression generally consisted of prednisone 1 mg/kg per day for 1 month, then tapered for both living-related and keratolimbal allografts; oral tacrolimus 4 mg twice daily, then tapered after 1 year for living-related and after 2 years for keratolimbal allografts; and mycophenolate mofetil 1 g twice daily, then tapered after 6–12 months for living-related and 2–3 years for keratolimbal allografts. Regimens were initiated 2 weeks prior to surgery and tailored ac1144
BCVA was converted from measured Snellen values to logarithm of the minimal angle of resolution (logMAR) for statistical analysis and averages were converted back to Snellen to be reported in the results. Distribution of data was assessed for normality using the Shapiro-Wilk test. Postoperative BCVA failed to demonstrate normality. Nonparametric Wilcoxon paired signed rank test was subsequently used to compare preoperative and postoperative logMAR values.
RESULTS RESULTS ARE SUMMARIZED IN THE TABLE. THE AVERAGE
age at diagnosis was 45.6 6 10.9 years (range 19–58 years) and the average age at surgery was 46.6 6 11.1 years (range 20–60 years). Eight right eyes and 6 left eyes were included. Most patients (67%; 6/9) were female and all patients wore soft contact lenses only. The mean duration of contact lens (CL) wear was 15.8 6 6.9 years (range 1–20 years), and 79% of eyes (11/14) had between 15 and 20 years of CL use. All patients wore CLs for the correction of refractive error and reported daily usage of 10 or more hours. All eyes had symptoms of at least 1 of the following: photophobia (9/14), redness (4/14), tearing (3/14), pain (2/14), or foreign body sensation (1/14). On average, 10.4 6 2.5 clock hours (range, 6–12 clock hours) of the limbus were affected. Conservative treatments were attempted in all patients consisting of discontinuation of CL, frequent preservative-free artificial tears, vitamin A ointment before bed, topical steroids 4 times daily, oral doxycycline 100 mg, and topical cyclosporine 0.05% twice daily, alone or in combination for at least 3 months. All patients had decreased BCVA at presentation, on average to 20/60 (range 20/30–20/250). Findings leading to a diagnosis of severe limbal stem cell deficiency included at least 6 clock hours of whorl-like epitheliopathy, an opaque epithelium arising from the limbus, late fluorescein staining of the involved epithelium, and superficial neovascularization or conjunctivalization. Complete conjunctivalization of the corneal surface was present in 64% of eyes (9/14). Bilateral severe limbal stem cell deficiency was present in 56% of patients (5/9). Conservative measures failed in all eyes. Average time from date of diagnosis to date of surgery was 9.8 months (range 1–32 months). Average preoperative visual acuity was 20/70 (range, 20/40–20/250). A total of 71% of eyes (10/14) underwent keratolimbal allograft and 29% (4/14) underwent living-related conjunctival
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TABLE. Demographic and Clinical Data of Patients With Contact Lens Wear–Related Severe Limbal Stem Cell Deficiency Treated With Limbal Stem Cell Transplantation
# Clock Hours of Eye Patient Age at Conjunctivalization No. No. Surgery (y) Sex Eye (Location)
Prior Treatments
Preoperative BCVA
Surgery
Follow-up Postoperative (mo) BCVA
Symptom Resolution
Side Effects Related to Systemic Immunosuppression
Systemic Immunosuppression at Last Follow-up
Other Surgery
LIMBAL STEM CELL TRANSPLANTATION IN CONTACT LENS WEAR LSCD
1
1
28
M OD
12 (Total)
Doxycycline
20/40
LR-CLAL
12
20/30
2
2
20
M OS
12 (Total)
Lotemax, vitamin A ointment
20/250
KLAL
12
20/20
3
3
44
F
OD
12 (Total)
20/200
LR-CLAL
21
20/30
4
3
44
F
OS
6 (Superior)
20/40
LR-CLAL
18
20/20
Complete Neutropenia
Mycophenolate mofetil
5
4
50
F
OS
12 (Total)
Superficial keratectomy, phototherapeutic keratectomy, Pred forte Superficial keratectomy, phototherapeutic keratectomy, Pred forte Meibomian gland dysfunction
20/70
70
20/30
Complete
None
Phaco, IOL
6
4
50
F
OD
12 (Total)
Meibomian gland dysfunction
20/80
65
20/30
Complete
None
Phaco, IOL
7
5
42
M OD
12 (Total)
20/50
28
20/20
Complete
6
60
F
OS
9 (Superior)
20/70
KLAL
33
20/25
Complete Nausea
Mycophenolate mofetil Mycophenolate mofetil
Phaco, IOL
8
9
6
60
F
OD
6 (Superior)
Lotemax, serum drops, artificial tears and ointment Vitamin A, nonpreserved artificial tears, temporal 70% lateral tarsorrhaphy for persistent epithelial defect Vitamin A ointment
KLAL þ lateral tarsorrhaphy KLAL þ lateral tarsorrhaphy KLAL
20/30
KLAL
18
20/20
Complete Nausea
Phaco, IOL
10
7
58
F
OD
12 (Total)
Vitamin A ointment
20/60
LR-CLAL
17
20/25
Complete
11
8
50
F
OS
12 (Total)
20/250
KLAL
12
20/30
Complete
12
8
50
F
OD
12 (Total)
20/100
KLAL
12
20/30
Complete
13 14
9 9
48 48
F F
OD OS
10 (Superior) 8 (Superior)
20/60 20/40
KLAL KLAL
33 41
20/150 20/50
Partiala Partiala
Mycophenolate mofetil Mycophenolate mofetil Mycophenolate mofetil þ tacrolimus Mycophenolate mofetil þ tacrolimus Tacrolimus Tacrolimus
Restasis, doxycycline Restasis, doxycycline
Complete
Mycophenolate mofetil þ tacrolimus Complete Hyperbilirubinemia Mycophenolate mofetil þ tacrolimus Complete Neutropenia Mycophenolate mofetil
Phaco, IOL
Phaco, IOL Phaco, IOL
Phaco, IOL
Phaco, IOL Phaco, IOL
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BCVA ¼ best-corrected visual acuity; IOL ¼ intraocular lens implant; KLAL ¼ keratolimbal allograft; LR-CLAL ¼ living-related conjunctival limbal allograft; Phaco ¼ phacoemulsification. Partial resolution of symptoms owing to patient’s severe rosacea-related blepharokeratoconjunctivitis and meibomian gland dysfunction.
a
limbal allograft surgery. After an average follow-up of 26 months (range 12–70 months) after transplantation, 86% of eyes (12/14 eyes) had total symptom resolution, a BCVA of 20/30 or better, and a stable ocular surface. The improvement in BCVA after limbal stem cell transplantation was statistically significant (P < .01). Two eyes from 1 patient with severe rosacea blepharokeratoconjunctivitis had an improved ocular surface. No vision improvement, from baseline 20/150 OD and 20/60 OS, was evident in this patient at last follow-up. No eyes required subsequent penetrating keratoplasty. With regard to patient systemic immunosuppression regimens, the average duration on prednisone use was 7.3 months (range 1.4–17 months). All patients were successfully tapered off of prednisone. At last follow-up, 5 of 9 patients and 2 of 9 patients, had successfully tapered off of tacrolimus and mycophenolate mofetil, respectively. The average duration of tacrolimus use before discontinuation was 24 months (range 16–34 months). The average duration on mycophenolate mofetil use before discontinuation was 24 months (range 23–25 months). Including patients still on immunosuppression at last follow-up, average duration on tacrolimus was 21 months (range 12–34 months) and on mycophenolate mofetil was 23 months (range 12–41 months). Adverse events included nausea in 1 patient 1 month after surgery, which resolved with over-the-counter antiemetics; increased bilirubin levels in 1 patient 1 week after surgery, which normalized after cessation of Bactrim prophylaxis; and neutropenia in 1 patient 8 months after surgery, which resolved after cessation of Bactrim prophylaxis and treatment with granulocyte colony-stimulating factor (G-CSF). Fifty-seven percent of eyes (8/14) experienced elevated IOP requiring topical antiglaucoma treatment. Seventy-one percent of eyes (10/14) underwent subsequent cataract extraction. No episodes of rejection were noted during follow-up. Pain, sectoral conjunctival injection, edema, and local epithelial abnormality leading to an epithelial defect were considered signs of allograft rejection.
DISCUSSION LIMBAL STEM CELL DEFICIENCY REPRESENTS THE COMMON
presentation of a heterogeneous group of underlying ocular surface disorders that include aniridia, chemical injury, burns, radiation, Stevens-Johnson syndrome, contact lens wear, and cicatricial pemphigoid, among others. Primary penetrating keratoplasty should be avoided in these cases because it is likely to fail and does not address the underlying problem. While a recent study demonstrated that some early forms of limbal stem cell deficiency may be reversible if the limbal stem cell niche is restored using only medical measures,12 most severe cases require the surgical restoration of the limbal stem cell population. This study is the 1146
largest series reported in the literature of limbal stem cell transplantation in a homogenous cohort of patients with severe subtotal or total contact lens wear–related limbal stem cell deficiency. The exact pathophysiology is not yet fully understood but likely involves a combination of hypoxia and mechanical factors affecting the limbal tissue.7 In our cohort of 9 patients, preoperative findings were comparable to other reports of contact lens wear–related limbal stem cell deficiency.7,13–16 For patients who seem to have unilateral disease, it may be tempting to perform conjunctival limbal autograft from the fellow eye. Some patients also may be hesitant to undergo allogeneic transplantation, which requires systemic immunosuppression. Extreme caution must be taken, as previous studies have shown that the normal-appearing fellow eye may have subclinical limbal stem cell deficiency, and an autograft in bilaterally exposed patients may fail to restore the corneal epithelial phenotype of the recipient eye and risk the integrity of the donor eye by depleting its stem cell reserve.17,18 Jenkins and associates17 detected encroachment of conjunctival epithelium on the recipient cornea in 3 of 4 severe contact lens wear–related limbal stem cell deficiency patients, all within 3 months of transplant, who received autografts from the fellow eye. In addition, 1 donor eye demonstrated epithelial changes and conjunctival migration suggestive of induced stem cell dysfunction at 13 months. In the 1 case where contact lens wear was unilateral, the patient achieved a stable ocular surface and improved VA from light perception preoperatively to 20/30 postoperatively. In a later series, Tan and associates18 similarly noted that the 2 patients that experienced graft failure in their mixed cohort of severe limbal stem cell deficiency patients were contact lens– wearing patients who received an autograft from fellow eyes that had previous evidence of mild clinical involvement. In 1 of those cases signs of an epithelial abnormality presented later in the donor eye. If a patient prefers that a conjunctival limbal autograft be performed, he or she must be counseled carefully regarding the risk that the surgery may cause the development of severe limbal stem cell deficiency in the fellow eye as well. It is not recommend that a conjunctival limbal autograft be performed in patients with a history of contact lens wear and who already have unilateral severe limbal stem cell deficiency. In this study, allogenic transplantation was the preferred technique, with living donor tissue used on 4 eyes (livingrelated conjunctival limbal allograft surgery) and cadaver donor tissue used for 10 eyes (keratolimbal allograft). In living-related conjunctival limbal allograft surgery, there is the advantage of a lower antigenic challenge, since histocompatability matching can be done between donor and recipient. The major disadvantages are the limitations in the amount of tissue capable of being harvested and the potential risks to the donor. As a result, the transplanted tissue is only able to cover approximately 50% of the recipient limbus.
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In keratolimbal allograft surgery, limbal tissue containing stem cells is obtained from a cadaveric donor and transplanted to the recipient eye. This procedure involves the transplantation of a complete 360-degree limbus and provides a larger stem cell load. Histocompatibility matching is not typically performed, because of impracticalities, at the eye bank that supplies the donor tissue. Because of the highly vascularized bed in which the transplanted tissue will reside, systemic immunosuppression is required for both living-related and keratolimbal allograft surgery. In our study, 86% of eyes (12/14) achieved a stable ocular surface, defined by an intact corneal epithelium and absence of corneal conjunctivalization and conjunctival inflammation. The same 12 eyes also showed a total resolution of preoperative symptoms (photophobia, foreign body sensation, tearing, redness, and pain) and improved vision to 20/30 or better. Even including the 2 eyes of the 1 patient that did not improve in vision, the overall improvement in BCVA was statistically significant. Our findings are similar to keratolimbal allograft and living-related conjunctival limbal allograft studies with analogous follow-up; however, heterogenous patient populations and varied immunosuppression protocols make direct comparisons difficult. With the use of systemic immunosuppression, Daya and Ilari19 reported more favorable results than previously published following living-related conjunctival limbal allograft20 in their mixed cohort of 10 eyes. After a mean follow-up of 26.2 months, 80% of eyes (8/10) achieved successful reepithelialization, 80% (8/10) had decreased corneal vascularization, and 100% of eyes (5/5) experienced symptomatic relief of pain. BCVA improved in 70% (7/10) and was unchanged in 30% of eyes (3/10). However, in 3 of 7 eyes, conjunctivalization recurred and in 6 of 10 eyes, corneal opacity remained evident at last follow-up. Holland3 reported on a mixed series of 25 eyes with an average of 26.4 months following keratolimbal allograft with systemic immunosuppression. A stable ocular surface was achieved in 72% of eyes (18/25) and an improvement in 2 lines or greater was achieved in 60% of eyes (15/25). A relatively meaningful comparison may exist between limbal stem cell transplantation outcomes in severe contact lens wear–related and aniridia-related limbal stem cell deficiency, as they are both classified as stage AII diseases where the conjunctiva is relatively normal without inflammation.6 In their homogenous cohort of 31 eyes with aniridic keratopathy undergoing keratolimbal allograft, Holland and associates21 showed a stable ocular surface in 74.2% of eyes (23/31) after a mean of 35.7 months follow-up. In addition, 87.1% of eyes (27/31) showed improvement in visual acuity. Despite the positive results in these studies, long-term reports of allogenic limbal stem cell transplantation with insufficient levels of systemic immunosuppression have shown attrition of the allogenic graft survival, ranging from 21.1% to 33.3% after 4 years of follow-up.22–24 VOL. 160, NO. 6
The excellent results achieved in our cohort of patients are likely a result of the combination of a rigorous immunosuppression regimen and the absence of any conjunctival inflammation in eyes with contact lens wear–related limbal stem cell deficiency. Limbal tissue contains Langerhans cells and sits on a well-vascularized bed, and thus is highly antigenic. Several studies have underscored the importance of systemic immunosuppression in the outcomes after limbal stem cell transplantation. Notably, in their aniridic cohort, Holland and associates21 found that following keratolimbal allograft, 90.5% of eyes (19/21) receiving systemic immunosuppression achieved a stable ocular surface vs only 40% of eyes (4/10) not receiving systemic immunosuppression. From least to most intensive, survival after allogeneic limbal stem cell transplant was reported at 23.7% at 5 years (cyclosporine only) by Solomon and associates,22 21.2% at 5 years (cyclosporine only) by Ilari and Daya,23 33.3% at 4 years (steroids, cyclosporine, and mycophenolate mofetil) by Han and associates,24 and 83% at 5 years (mycophenolate mofetil and tacrolimus) by Liang and associates.25 Numerous other differences exist between these studies and care should be taken in interpreting this trend. More recently, a comparison of number of HLA matches in limbal stem cell transplant by Reinhard and associates26 demonstrated that in the long-term survival of livingrelated conjunctival limbal allografts, 65% with 0 or 1 mismatched HLA markers survived at 5 years vs 41% of grafts with 2–6 mismatches and 14% of untyped grafts, further underscoring the role of immunogenicity. In our study, all patients received systemic prednisone, tacrolimus, and mycophenolate mofetil, which has previously been shown to be safe and effective in limbal stem cell transplantation.27 Previous evaluation of this regimen revealed severe adverse events in 1.5% of patients and minor adverse events (elevated creatinine, hypertension, diabetes, pneumonia, avascular necrosis) in 14% of patients, mostly related to tacrolimus. In our cohort, this immunosuppression protocol was generally well tolerated. Two patients experienced side effects associated with Bactrim prophylaxis use. Of those, 1 patient experienced elevated bilirubin levels, which resolved with cessation of the drug; the other patient developed neutropenia, which resolved with cessation and treatment with G-CSF. A third patient experienced nonspecific nausea, which was treated effectively with antiemetics. A common complication after limbal stem cell transplantation is an increase in intraocular pressure, with studies reporting rates of 33.1%,23 37.2%,28 and 37.5%.24 The cause of this may be due to the removal of fibrous tissue in the recipient eye, taking with it draining vessels responsible for the outflow of aqueous humor.28 In our study, we had a higher incidence of elevated intraocular pressure, with 57% of eyes (8/14) requiring topical antiglaucoma treatment. In addition, 71% of eyes (10/14) required subsequent cataract extraction, markedly higher than previously reported by Baradaran-Rafii and associates29 at 17.8%.
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In addition to immunogenicity, several other factors have been associated with poorer outcomes following limbal stem cell transplantation, including severe dry eye, keratinization, eyelid scarring, symblepharon, lagophthalmos, and inflammatory conditions.6,20,24 In contact lens wear–related limbal stem cell deficiency, the conjunctiva is relatively noninflamed. In more severe ocular surface disease where the conjunctiva has been previously or is still actively inflamed, appropriate sequential treatment of coexisting conditions must be taken before attempting any ocular surface stem cell transplantation. Higher incidences of graft failure have been reported by several studies of Stevens-Johnson syndrome patients, where persistent inflammation, fibrosis, and tear film abnormalities create an unfavorable environment and contribute to persistent stem cell exhaustion.22,30,31 In our 1 patient (2 eyes) that achieved only an improved ocular surface, with areas of healthy cornea and areas of abnormal conjunctival epithelium, the patient suffered from significant rosacea blepharokeratoconjunctivitis. Interestingly, keratolimbal allograft surgery was performed in this patient owing to lack of living-donor availability. A procedure using tissue from a live donor may have potentially conferred more benefit to this patient by providing healthy donor conjunctiva with goblet cells as well. Contemporary limbal stem cell transplantation techniques for bilateral disease have evolved to include the use of ex vivo culture methods that are associated with their own advantages and disadvantages. Variability in inclusion criteria, source of cells, substrates and culture techniques, and immunosuppression methods exist. Despite this, Baylis and associates32 found no significant difference in the clinical outcomes of culture limbal epithelial transplantation regardless of culture technique, donor tissue, and indication. For allogenic procedures, they reported a 77% overall success rate, most commonly defined as a fully epithelialized and avascular cornea, in their systemic review including 93 cases. Other options for bilateral limbal stem cell deficiency include alternative tissue sources, of which only oral mucosal epithelium has been investigated in humans.33 Practically, the high cost of establishing and maintaining an ex vivo stem cell laboratory limit their applicability to only a few tertiary centers worldwide.34 In the last few years, a new technique, simple limbal epithelial transplantation, wherein limbal stem cells are expanded in vivo over an amniotic membrane placed over the surface of a cornea, has been reported in
the literature, showing promising results.35 So far, this procedure has primarily been performed using autologous tissue. However, 1 case report exists that demonstrated acceptable visual outcomes in a case of allogenic simple limbal epithelial transplantation.36 Of note, graft rejection occurred at 4 months, which was managed successfully with steroids but caused the authors to conclude that a more aggressive immunosuppresion regimen may be required. Limitations of this study include its retrospective nature and the limited sample size. Also, although impression cytologic analysis has been used in other studies to diagnose limbal stem cell deficiency, it was not performed on the patients in this series. Clinical findings on slit-lamp examination of late fluorescein staining and the hazy, thickened abnormal epithelium progressive from the limbus that did not resolve with supportive therapy are hallmark clinical signs of limbal stem cell deficiency. In addition, pathologic analysis of the corneal pannus removed during the surgeries indicated presence of conjunctival goblet cells, which is diagnostic for the conjunctivalization of the corneal surface that occurs in limbal stem cell deficiency. Because of sample size, subgroup analysis between the 2 techniques was not possible. Nevertheless, this study represents the largest series reported in the literature of a homogenous cohort of severe subtotal-total limbal stem cell deficiency, related to contact lens wear, treated with limbal stem cell transplantation. We are able to show promising outcomes in these patients who have failed conservative treatment and where traditional corneal transplant would not be appropriate. It is important for ophthalmologists to recognize this condition and the treatment options available, including surgery. In conclusion, limbal stem cell transplantation with systemic immunosuppression is a viable surgical option for these young and otherwise healthy patients presenting with severe contact lens wear–related limbal stem cell deficiency. Early intervention prior to the development of subepithelial fibrosis can lead to symptom relief and excellent visual outcomes without the need for subsequent corneal transplant. Monitoring for intraocular pressure elevation and cataract formation secondary to topical immunosuppression is important. Co-management with a transplant specialist is helpful for the monitoring and management of systemic adverse effects. Further studies are required to examine the long-term outcomes of living and cadaver transplanted tissue in these patients.
FUNDING/SUPPORT: NO FUNDING OR GRANT SUPPORT. FINANCIAL DISCLOSURES: CLARA C. CHAN HAS RECEIVED HONORARIA from Allergan (Irvine, California), Bausch & Lomb (Bridgewater, New Jersey), Alcon Laboratories Inc (Fort Worth, Texas), and Tearscience (Morrisville, North Carolina). Edward J. Holland has consulted for Alcon Laboratories Inc (Fort Worth, Texas), Bausch & Lomb (Bridgewater, New Jersey), Kala Corporation (Waltham, Massachusetts), Mati Therapeutics (Austin, Texas), PRN (Plymouth Meeting, Pennsylvania), RPS (Fort Washington, Philadelphia), Senju Pharmaceuticals (Woodland Hills, California), Tearscience (Morrisville, North Carolina), and TearLab (San Diego, California). The following author has no financial disclosures: Carl Shen. All authors attest that they meet the current ICMJE criteria for authorship.
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REFERENCES 1. Huang AJ, Tseng SC. Corneal epithelial wound healing in the absence of limbal epithelium. Invest Ophthalmol Vis Sci 1991;32(1):96–105. 2. Shapiro MS, Friend J, Thoft RA. Corneal re-epithelialization from the conjunctiva. Invest Ophthalmol Vis Sci 1981;21(1): 135–142. 3. Holland EJ. Epithelial transplantation for the management of severe ocular surface disease. Trans Am Ophthalmol Soc 1996; 94(1):677–743. 4. Huang AJ, Tseng SC, Kenyon KR. Alteration of epithelial paracellular permeability during corneal epithelial wound healing. Invest Ophthalmol Vis Sci 1990;31(3):429–435. 5. Puangsricharern V, Tseng SC. Cytologic evidence of corneal diseases with limbal stem cell deficiency. Ophthalmology 1995; 102(10):1476–1485. 6. Holland EJ, Schwartz GS. The evolution of epithelial transplantation for severe ocular surface disease and a proposed classification system. Cornea 1996;15(6):549–556. 7. Chan CC, Holland EJ. Severe limbal stem cell deficiency from contact lens wear: patient clinical features. Am J Ophthalmol 2013;155(3):544–549. 8. Jeng BH, Halfpenny CP, Meisler DM, Stock EL. Management of focal limbal stem cell deficiency associated with soft contact lens wear. Cornea 2011;30(1):18–23. 9. Croasdale CR, Schwartz GS, Malling JV, Holland EJ. Keratolimbal allograft: recommendations for tissue procurement and preparation by eye banks, and standard surgical technique. Cornea 1999;18(1):52–58. 10. Daya SM, Holland E, Mannis M. Ocular Surface Disease Medical and Surgical Management. New York: SpringerVerlag; 2002. 11. Biber JM, Skeens HM, Neff KD, Holland EJ. The Cincinnati procedure: technique and outcomes of combined living-related conjunctival limbal allografts and keratolimbal allografts in severe ocular surface failure. Cornea 2011;30(7):765–771. 12. Kim BY, Riaz KM, Bakhtiari P, et al. Medically reversible limbal stem cell disease: clinical features and management strategies. Ophthalmology 2014;121(10):2053–2058. 13. Clinch TE, Goins KM, Cobo LM. Treatment of contact lensrelated ocular surface disorders with autologous conjunctival transplantation. Ophthalmology 1992;99(4):634–638. 14. Bloomfield SE, Jakobiec FA, Theodore FH. Contact lens induced keratopathy: a severe complication extending the spectrum of keratoconjunctivitis in contact lens wearers. Ophthalmology 1984;91(3):290–294. 15. Bhatia RP, Srivastava R, Ghosh A. Limbal stem cell study in contact lens wearers. Ann Ophthalmol (Skokie) 2009;41(2):87–92. 16. Martin R. Corneal conjunctivalisation in long-standing contact lens wearers. Clin Exp Optom 2007;90(1):26–30. 17. Jenkins C, Tuft S, Liu C, Buckley R. Limbal transplantation in the management of chronic contact-lens-associated epitheliopathy. Eye (Lond) 1993;7(5):629–633. 18. Tan DT, Ficker LA, Buckley RJ. Limbal transplantation. Ophthalmology 1996;103(1):29–36. 19. Daya SM, Ilari FA. Living related conjunctival limbal allograft for the treatment of stem cell deficiency. Ophthalmology 2001;108(1):126–133.
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20. Rao SK, Rajagopal R, Sitalakshmi G, Padmanabhan P. Limbal allografting from related live donors for corneal surface reconstruction. Ophthalmology 1999;106(4):822–828. 21. Holland EJ, Djalilian AR, Schwartz GS. Management of aniridic keratopathy with keratolimbal allograft: a limbal stem cell transplantation technique. Ophthalmology 2003; 110(1):125–130. 22. Solomon A, Ellies P, Anderson DF, et al. Long-term outcome of keratolimbal allograft with or without penetrating keratoplasty for total limbal stem cell deficiency. Ophthalmology 2002;109(6):1159–1166. 23. Ilari L, Daya SM. Long-term outcomes of keratolimbal allograft for the treatment of severe ocular surface disorders. Ophthalmology 2002;109(7):1278–1284. 24. Han ES, Wee WR, Lee JH, Kim MK. Long-term outcome and prognostic factor analysis for keratolimbal allografts. Graefes Arch Clin Exp Ophthalmol 2011;249(11):1697–1704. 25. Liang L, Sheha H, Tseng SCG. Long-term outcomes of keratolimbal allograft for total limbal stem cell deficiency using combined immunosuppressive agents and correction of ocular surface deficits. Arch Ophthalmol 2009;127(11): 1428–1434. 26. Reinhard T, Spelsberg H, Henke L, et al. Long-term results of allogeneic penetrating limbo-keratoplasty in total limbal stem cell deficiency. Ophthalmology 2004;111(4):775–782. 27. Holland EJ, Mogilishetty G, Skeens HM, et al. Systemic immunosuppression in ocular surface stem cell transplantation: results of a 10-year experience. Cornea 2012;31(6):655–661. 28. Tsubota K, Shimmura S, Shinozaki N, Holland EJ, Shimazaki J. Clinical application of living-related conjunctival-limbal allograft. Am J Ophthalmol 2002;133(1):134–135. 29. Baradaran-Rafii A, Eslani M, Djalillian AR. Complications of keratolimbal allograft surgery. Cornea 2013;32(5):561–566. 30. Maruyama-Hosoi F, Shimazaki J, Shimmura S, Tsubota K. Changes observed in keratolimbal allograft. Cornea 2006; 25(4):377–382. 31. Santos MS, Gomes JAP, Hofling-Lima AL, Rizzo LV, Romano AC, Belfort R. Survival analysis of conjunctival limbal grafts and amniotic membrane transplantation in eyes with total limbal stem cell deficiency. Am J Ophthalmol 2005;140(2):223–230. 32. Baylis O, Figueiredo F, Henein C, Lako M, Ahmad S. 13 years of cultured limbal epithelial cell therapy: a review of the outcomes. J Cell Biochem 2011;112(4):993–1002. 33. Burillon C, Huot L, Justin V, et al. Cultured autologous oral mucosal epithelial cell sheet (CAOMECS) transplantation for the treatment of corneal limbal epithelial stem cell deficiency. Invest Ophthalmol Vis Sci 2012;53:1325–1331. 34. Miri A, Al-Deiri B, Dua HS. Long-term outcomes of autolimbal and allolimbal transplants. Ophthalmology 2010;117(6): 1207–1213. 35. Sangwan VS, Basu S, MacNeil S, Balasubramanian D. Simple limbal epithelial transplantation (SLET): a novel surgical technique for the treatment of unilateral limbal stem cell deficiency. Br J Ophthalmol 2012;96(7):931–934. 36. Bhalekar S, Basu S, Sangwan VS. Successful management of immunological rejection following allogeneic simple limbal epithelial transplantation (SLET) for bilateral ocular burns. BMJ Case Rep. http://dx.doi.org/10.1136/bcr.2013.009051.
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Biosketch Carl Shen, BMSc, is currently a fourth-year medical student at the University of Toronto, Ontario, Canada. He has been involved in a variety of research projects at the Harvard Stem Cell Institute, TLC Laser Eye Centre, Toronto Western Research Institute, and the Hospital for Sick Children.
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To describe the outcomes of limbal stem cell transplantation in eyes with limbal stem cell deficiency related to soft contact lens wear. DESIGN: Retrospective interventional case series. METHODS: Institutional database search at the Cincinnati Eye Institute revealed 9 patients (14 eyes) who underwent limbal stem cell transplantation with systemic immunosuppression for soft contact lens wear–related limbal stem cell deficiency. Outcome measures included patient demographics, symptoms, best-corrected visual acuity, ocular surface stability, adverse events, and additional surgeries required. RESULTS: Average patient age at time of surgery was 46.6 ± 11.1 years (range 20–60 years). Average duration of follow-up was 28 ± 19.1 months (range 12– 70 months). Preoperative best-corrected visual acuity (BCVA) was 20/40 or worse in all eyes (average 20/70, range 20/40–20/250) and patient symptoms included foreign body sensation, tearing, redness, and/or pain. Four eyes (29%) underwent living-related conjunctival limbal allograft and 10 eyes (71%) underwent cadaverdonor keratolimbal allograft surgery. Topical and systemic immunosuppression was used in all patients. At final follow-up after limbal stem cell transplantation, there was a stable ocular surface in 12 of 14 eyes (86%) and improvement in BCVA to 20/30 or better and complete resolution of patient symptoms in all except 1 patient who had significant rosacea blepharokeratoconjunctivitis, whose BCVA remained at 20/150 and 20/60, in right and left eyes, respectively. The most common adverse event was an increase in intraocular pressure in 8 of 14 eyes (57%), requiring topical antiglaucoma treatment. Ten of 14 eyes (71%) underwent cataract extraction related to topical steroid use. No eyes required subsequent penetrating keratoplasty.
Accepted for publication Jul 31, 2015. From the University of Toronto Medical School, Toronto, Canada (C.S.); and Cincinnati Eye Institute, Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio (C.C.C., E.J.H.). Dr Clara C. Chan is now on faculty at the Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada. Inquiries to Clara C. Chan, Department of Ophthalmology and Vision Sciences, University of Toronto, 600 Sherbourne St, Suite 601, Toronto, Ontario M4X1W4, Canada; e-mail: [email protected]
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Ó
2015 BY
CONCLUSION:
Limbal stem cell transplantation is a viable option for the management of soft contact lens wear–related limbal stem cell deficiency in young healthy patients. Early intervention prior to subepithelial fibrosis can lead to good visual outcomes with no need for subsequent cornea transplant. Co-management with a solid organ transplant specialist is helpful for the monitoring and management of systemic adverse events related to patient systemic immunosuppression. (Am J Ophthalmol 2015;160(6):1142–1149. Ó 2015 by Elsevier Inc. All rights reserved.)
L
IMBAL STEM CELLS ARE REQUIRED FOR THE MAINTE-
nance of a stable corneal epithelial surface and act as a barrier to any conjunctivalization of the cornea.1,2 The loss or dysfunction of the limbal stem cells results in limbal stem cell deficiency. Clinically, this manifests as persistent epithelial defects, corneal conjunctivalization, corneal scarring, chronic inflammation, vision loss, chronic pain, photophobia, and keratoplasty failure.3 On examination, the epithelium may appear opaque, and/or a classic pattern of late fluorescein corneal staining occurs (Figure) because of the increased permeability of abnormal epithelial cells.4 In addition, migrating conjunctival goblet cells can be detected on the corneal surface by impression cytology.5 Numerous causes of limbal stem cell deficiency exist, including aniridia, chemical injury, burns, radiation, Stevens-Johnson syndrome, contact lens wear, and cicatricial pemphigoid, among others. Limbal stem cell deficiency can be staged according to amount of limbal involvement and the inflammatory status of the conjunctiva.6 Severe limbal stem cell deficiency is a rare complication of contact lens wear that has been associated with female sex and extended duration of wear time.7 It is classified as stage AII by a loss of limbal stem cells greater than 6 clock hours (near total) up to 12 clock hours (total). In less severe or partial contact lens wear–related limbal stem cell deficiency (stage AI), patients can be managed with conservative treatment consisting of the discontinuation of contact lens wear, management of dry eye and blepharitis, epithelial debridement and amniotic membrane graft, and/or sequential epithelial debridement.8 However, in severe contact lens wear–related limbal stem cell deficiency, limbal stem cell transplantation is required for restoration
ELSEVIER INC. ALL
RIGHTS RESERVED.
0002-9394/$36.00 http://dx.doi.org/10.1016/j.ajo.2015.07.038
FIGURE. Photograph of severe limbal stem cell deficiency in the right eye of Patient 3. (Top left) Note the abnormal opaque epithelium arising from the superior limbus and extending into the visual axis. (Top right) Note the whorl-like epitheliopathy with classic late fluorescein staining pattern superiorly and inferiorly, and through the visual axis. (Bottom left) Five months later, there is progression of the patient’s disease with total surface late fluorescein staining and corneal erosion causing reduced vision to 20/200. (Bottom right) Twenty-one months after undergoing living-related conjunctival limbal allograft from donor brother. Note the smooth corneal epithelium with clear corneal light reflex.
of the corneal phenotype. Keratolimbal allograft and living-related conjunctival limbal allograft are 2 techniques for transplanting allogenic tissue containing limbal stem cells into a recipient eye. The purpose of this study was to describe the outcomes of limbal stem cell transplantation by keratolimbal allograft and living-related conjunctival limbal allograft in the treatment of severe contact lens wear–related limbal stem cell deficiency.
corrected visual acuity (BCVA), type of limbal stem cell transplant, ocular surface stability, adverse events, and additional surgeries required. A stable ocular surface was defined as an intact corneal epithelium and absence of corneal conjunctivalization and conjunctival inflammation. An improved ocular surface was defined as a partial failure with areas of healthy cornea and areas of abnormal conjunctival epithelium. SURGICAL
METHODS THIS RETROSPECTIVE STUDY WAS REVIEWED BY THE ST ELIZ-
abeth’s Health Care (Edgewood, Kentucky) Institutional Review Board (IRB # 4/2011-009) and determined to be exempt. This study was conducted in compliance with the tenets of the Declaration of Helsinki. PATIENTS: A database search of patients with a diagnosis of severe limbal stem cell deficiency related to contact lens wear was conducted at a single institution. The charts of 18 eyes from 12 patients were identified. Of those, 14 eyes from 9 patients had undergone limbal stem cell transplantation and their charts were retrospectively reviewed. Outcome measures that were analyzed consisted of patient demographics, presenting symptoms, change in best-
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PROCEDURES: Keratolimbal allograft. The protocol for tissue procurement and preparation was followed, and this surgical technique has been described previously.9 Briefiy, paired corneoscleral rims were used as the source for transplanted limbal stem cells. The central cornea was excised with a 7.5 mm trephine. The remaining corneoscleral rim was sectioned into 2 equal halves, and excess peripheral scleral tissue was trimmed. The posterior one half to two thirds of each hemisection was removed via lamellar dissection using a steel crescent blade and then discarded. A 360-degree limbal peritomy was performed on the recipient eye. The conjunctiva was resected for 4–5 mm to expose an adequate area of sclera on which to position the allograft tissue. Abnormal fibrovascular pannus and epithelium were removed from the cornea with a combination of sharp and blunt dissection. Three of the 4 dissected crescents were placed on the recipient eye with the donor corneal edge
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overlying the recipient limbus secured with 10-0 nylon interrupted buried sutures and with tissue glue for the base. The recipient conjunctival edge was ensured to abut the posterior edge of the transplanted tissue.
cording to the degree of conjunctival inflammation. Valganciclovir 225 mg daily for 1 year (discontinued if CMV IgG negative) and sulfamethoxazole and trimethoprim 1 tablet 3 times weekly were given as prophylaxis.
Living-related conjunctival limbal allograft. The protocol for tissue procurement and preparation was followed, and this surgical technique has been described previously.10 Briefly, the best match from potential donors was identified from immediate relatives based on human leukocyte antigen and ABO blood typing. Donors were assessed preoperatively for transmissible diseases and to ensure there were no ocular pathologic conditions present. The nondominant eye was selected as the donor. In the donor eye, 3 clock hours of limbal conjunctival tissue at the 12- and 6-o’clock positions were marked with a gentian violet blue marker and resected 3–4 mm posteriorly. Conjunctival tissue, including the Vogt palisades, was dissected 1 mm anteriorly onto the corneal surface. Vannas scissors were then used to cut the conjunctiva from the cornea. The 2 pieces of donor tissue were floated on balanced salt solution (Alcon, Fort Worth, Texas, USA) and transferred for transplantation to the recipient. The conjunctival wounds were then closed 1 mm posterior to the limbus using 10-0 vicryl sutures (Ethicon, Johnson & Johnson, Cincinnati, OH). Subconjunctival injections of ancef and dexamethasone were given. A topical-fourth generation fluoroquinolone was applied and the eye was patched. In the recipient, a conjunctival peritomy was performed at the 12- and 6-o’clock positions, and limbal conjunctiva was undermined and allowed to retract posteriorly. Removal of pannus and irregular epithelium was performed by debridement and careful dissection using a 64 blade. The conjunctival-limbal grafts were secured at the limbus using 10-0 nylon sutures and at the base with tissue glue. Subconjunctival injections of cefazolin and dexamethasone were administered. A large-diameter contact lens was placed and a patch applied.
STATISTICAL ANALYSIS:
IMMUNOSUPPRESSION REGIMEN:
All patients received an immunosuppression regimen as previously described.11 In brief, postoperatively, patients were given topical cyclosporine 0.05% 2 times daily and prednisolone acetate or difluprednate 1% 4 times daily. Topical steroid was maintained at 4 times daily for the first 3 months and then decreased by 1 drop per month. Patients were then maintained on topical steroids at least once daily according to the degree of conjunctival inflammation. Systemic immunosuppression generally consisted of prednisone 1 mg/kg per day for 1 month, then tapered for both living-related and keratolimbal allografts; oral tacrolimus 4 mg twice daily, then tapered after 1 year for living-related and after 2 years for keratolimbal allografts; and mycophenolate mofetil 1 g twice daily, then tapered after 6–12 months for living-related and 2–3 years for keratolimbal allografts. Regimens were initiated 2 weeks prior to surgery and tailored ac1144
BCVA was converted from measured Snellen values to logarithm of the minimal angle of resolution (logMAR) for statistical analysis and averages were converted back to Snellen to be reported in the results. Distribution of data was assessed for normality using the Shapiro-Wilk test. Postoperative BCVA failed to demonstrate normality. Nonparametric Wilcoxon paired signed rank test was subsequently used to compare preoperative and postoperative logMAR values.
RESULTS RESULTS ARE SUMMARIZED IN THE TABLE. THE AVERAGE
age at diagnosis was 45.6 6 10.9 years (range 19–58 years) and the average age at surgery was 46.6 6 11.1 years (range 20–60 years). Eight right eyes and 6 left eyes were included. Most patients (67%; 6/9) were female and all patients wore soft contact lenses only. The mean duration of contact lens (CL) wear was 15.8 6 6.9 years (range 1–20 years), and 79% of eyes (11/14) had between 15 and 20 years of CL use. All patients wore CLs for the correction of refractive error and reported daily usage of 10 or more hours. All eyes had symptoms of at least 1 of the following: photophobia (9/14), redness (4/14), tearing (3/14), pain (2/14), or foreign body sensation (1/14). On average, 10.4 6 2.5 clock hours (range, 6–12 clock hours) of the limbus were affected. Conservative treatments were attempted in all patients consisting of discontinuation of CL, frequent preservative-free artificial tears, vitamin A ointment before bed, topical steroids 4 times daily, oral doxycycline 100 mg, and topical cyclosporine 0.05% twice daily, alone or in combination for at least 3 months. All patients had decreased BCVA at presentation, on average to 20/60 (range 20/30–20/250). Findings leading to a diagnosis of severe limbal stem cell deficiency included at least 6 clock hours of whorl-like epitheliopathy, an opaque epithelium arising from the limbus, late fluorescein staining of the involved epithelium, and superficial neovascularization or conjunctivalization. Complete conjunctivalization of the corneal surface was present in 64% of eyes (9/14). Bilateral severe limbal stem cell deficiency was present in 56% of patients (5/9). Conservative measures failed in all eyes. Average time from date of diagnosis to date of surgery was 9.8 months (range 1–32 months). Average preoperative visual acuity was 20/70 (range, 20/40–20/250). A total of 71% of eyes (10/14) underwent keratolimbal allograft and 29% (4/14) underwent living-related conjunctival
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TABLE. Demographic and Clinical Data of Patients With Contact Lens Wear–Related Severe Limbal Stem Cell Deficiency Treated With Limbal Stem Cell Transplantation
# Clock Hours of Eye Patient Age at Conjunctivalization No. No. Surgery (y) Sex Eye (Location)
Prior Treatments
Preoperative BCVA
Surgery
Follow-up Postoperative (mo) BCVA
Symptom Resolution
Side Effects Related to Systemic Immunosuppression
Systemic Immunosuppression at Last Follow-up
Other Surgery
LIMBAL STEM CELL TRANSPLANTATION IN CONTACT LENS WEAR LSCD
1
1
28
M OD
12 (Total)
Doxycycline
20/40
LR-CLAL
12
20/30
2
2
20
M OS
12 (Total)
Lotemax, vitamin A ointment
20/250
KLAL
12
20/20
3
3
44
F
OD
12 (Total)
20/200
LR-CLAL
21
20/30
4
3
44
F
OS
6 (Superior)
20/40
LR-CLAL
18
20/20
Complete Neutropenia
Mycophenolate mofetil
5
4
50
F
OS
12 (Total)
Superficial keratectomy, phototherapeutic keratectomy, Pred forte Superficial keratectomy, phototherapeutic keratectomy, Pred forte Meibomian gland dysfunction
20/70
70
20/30
Complete
None
Phaco, IOL
6
4
50
F
OD
12 (Total)
Meibomian gland dysfunction
20/80
65
20/30
Complete
None
Phaco, IOL
7
5
42
M OD
12 (Total)
20/50
28
20/20
Complete
6
60
F
OS
9 (Superior)
20/70
KLAL
33
20/25
Complete Nausea
Mycophenolate mofetil Mycophenolate mofetil
Phaco, IOL
8
9
6
60
F
OD
6 (Superior)
Lotemax, serum drops, artificial tears and ointment Vitamin A, nonpreserved artificial tears, temporal 70% lateral tarsorrhaphy for persistent epithelial defect Vitamin A ointment
KLAL þ lateral tarsorrhaphy KLAL þ lateral tarsorrhaphy KLAL
20/30
KLAL
18
20/20
Complete Nausea
Phaco, IOL
10
7
58
F
OD
12 (Total)
Vitamin A ointment
20/60
LR-CLAL
17
20/25
Complete
11
8
50
F
OS
12 (Total)
20/250
KLAL
12
20/30
Complete
12
8
50
F
OD
12 (Total)
20/100
KLAL
12
20/30
Complete
13 14
9 9
48 48
F F
OD OS
10 (Superior) 8 (Superior)
20/60 20/40
KLAL KLAL
33 41
20/150 20/50
Partiala Partiala
Mycophenolate mofetil Mycophenolate mofetil Mycophenolate mofetil þ tacrolimus Mycophenolate mofetil þ tacrolimus Tacrolimus Tacrolimus
Restasis, doxycycline Restasis, doxycycline
Complete
Mycophenolate mofetil þ tacrolimus Complete Hyperbilirubinemia Mycophenolate mofetil þ tacrolimus Complete Neutropenia Mycophenolate mofetil
Phaco, IOL
Phaco, IOL Phaco, IOL
Phaco, IOL
Phaco, IOL Phaco, IOL
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BCVA ¼ best-corrected visual acuity; IOL ¼ intraocular lens implant; KLAL ¼ keratolimbal allograft; LR-CLAL ¼ living-related conjunctival limbal allograft; Phaco ¼ phacoemulsification. Partial resolution of symptoms owing to patient’s severe rosacea-related blepharokeratoconjunctivitis and meibomian gland dysfunction.
a
limbal allograft surgery. After an average follow-up of 26 months (range 12–70 months) after transplantation, 86% of eyes (12/14 eyes) had total symptom resolution, a BCVA of 20/30 or better, and a stable ocular surface. The improvement in BCVA after limbal stem cell transplantation was statistically significant (P < .01). Two eyes from 1 patient with severe rosacea blepharokeratoconjunctivitis had an improved ocular surface. No vision improvement, from baseline 20/150 OD and 20/60 OS, was evident in this patient at last follow-up. No eyes required subsequent penetrating keratoplasty. With regard to patient systemic immunosuppression regimens, the average duration on prednisone use was 7.3 months (range 1.4–17 months). All patients were successfully tapered off of prednisone. At last follow-up, 5 of 9 patients and 2 of 9 patients, had successfully tapered off of tacrolimus and mycophenolate mofetil, respectively. The average duration of tacrolimus use before discontinuation was 24 months (range 16–34 months). The average duration on mycophenolate mofetil use before discontinuation was 24 months (range 23–25 months). Including patients still on immunosuppression at last follow-up, average duration on tacrolimus was 21 months (range 12–34 months) and on mycophenolate mofetil was 23 months (range 12–41 months). Adverse events included nausea in 1 patient 1 month after surgery, which resolved with over-the-counter antiemetics; increased bilirubin levels in 1 patient 1 week after surgery, which normalized after cessation of Bactrim prophylaxis; and neutropenia in 1 patient 8 months after surgery, which resolved after cessation of Bactrim prophylaxis and treatment with granulocyte colony-stimulating factor (G-CSF). Fifty-seven percent of eyes (8/14) experienced elevated IOP requiring topical antiglaucoma treatment. Seventy-one percent of eyes (10/14) underwent subsequent cataract extraction. No episodes of rejection were noted during follow-up. Pain, sectoral conjunctival injection, edema, and local epithelial abnormality leading to an epithelial defect were considered signs of allograft rejection.
DISCUSSION LIMBAL STEM CELL DEFICIENCY REPRESENTS THE COMMON
presentation of a heterogeneous group of underlying ocular surface disorders that include aniridia, chemical injury, burns, radiation, Stevens-Johnson syndrome, contact lens wear, and cicatricial pemphigoid, among others. Primary penetrating keratoplasty should be avoided in these cases because it is likely to fail and does not address the underlying problem. While a recent study demonstrated that some early forms of limbal stem cell deficiency may be reversible if the limbal stem cell niche is restored using only medical measures,12 most severe cases require the surgical restoration of the limbal stem cell population. This study is the 1146
largest series reported in the literature of limbal stem cell transplantation in a homogenous cohort of patients with severe subtotal or total contact lens wear–related limbal stem cell deficiency. The exact pathophysiology is not yet fully understood but likely involves a combination of hypoxia and mechanical factors affecting the limbal tissue.7 In our cohort of 9 patients, preoperative findings were comparable to other reports of contact lens wear–related limbal stem cell deficiency.7,13–16 For patients who seem to have unilateral disease, it may be tempting to perform conjunctival limbal autograft from the fellow eye. Some patients also may be hesitant to undergo allogeneic transplantation, which requires systemic immunosuppression. Extreme caution must be taken, as previous studies have shown that the normal-appearing fellow eye may have subclinical limbal stem cell deficiency, and an autograft in bilaterally exposed patients may fail to restore the corneal epithelial phenotype of the recipient eye and risk the integrity of the donor eye by depleting its stem cell reserve.17,18 Jenkins and associates17 detected encroachment of conjunctival epithelium on the recipient cornea in 3 of 4 severe contact lens wear–related limbal stem cell deficiency patients, all within 3 months of transplant, who received autografts from the fellow eye. In addition, 1 donor eye demonstrated epithelial changes and conjunctival migration suggestive of induced stem cell dysfunction at 13 months. In the 1 case where contact lens wear was unilateral, the patient achieved a stable ocular surface and improved VA from light perception preoperatively to 20/30 postoperatively. In a later series, Tan and associates18 similarly noted that the 2 patients that experienced graft failure in their mixed cohort of severe limbal stem cell deficiency patients were contact lens– wearing patients who received an autograft from fellow eyes that had previous evidence of mild clinical involvement. In 1 of those cases signs of an epithelial abnormality presented later in the donor eye. If a patient prefers that a conjunctival limbal autograft be performed, he or she must be counseled carefully regarding the risk that the surgery may cause the development of severe limbal stem cell deficiency in the fellow eye as well. It is not recommend that a conjunctival limbal autograft be performed in patients with a history of contact lens wear and who already have unilateral severe limbal stem cell deficiency. In this study, allogenic transplantation was the preferred technique, with living donor tissue used on 4 eyes (livingrelated conjunctival limbal allograft surgery) and cadaver donor tissue used for 10 eyes (keratolimbal allograft). In living-related conjunctival limbal allograft surgery, there is the advantage of a lower antigenic challenge, since histocompatability matching can be done between donor and recipient. The major disadvantages are the limitations in the amount of tissue capable of being harvested and the potential risks to the donor. As a result, the transplanted tissue is only able to cover approximately 50% of the recipient limbus.
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In keratolimbal allograft surgery, limbal tissue containing stem cells is obtained from a cadaveric donor and transplanted to the recipient eye. This procedure involves the transplantation of a complete 360-degree limbus and provides a larger stem cell load. Histocompatibility matching is not typically performed, because of impracticalities, at the eye bank that supplies the donor tissue. Because of the highly vascularized bed in which the transplanted tissue will reside, systemic immunosuppression is required for both living-related and keratolimbal allograft surgery. In our study, 86% of eyes (12/14) achieved a stable ocular surface, defined by an intact corneal epithelium and absence of corneal conjunctivalization and conjunctival inflammation. The same 12 eyes also showed a total resolution of preoperative symptoms (photophobia, foreign body sensation, tearing, redness, and pain) and improved vision to 20/30 or better. Even including the 2 eyes of the 1 patient that did not improve in vision, the overall improvement in BCVA was statistically significant. Our findings are similar to keratolimbal allograft and living-related conjunctival limbal allograft studies with analogous follow-up; however, heterogenous patient populations and varied immunosuppression protocols make direct comparisons difficult. With the use of systemic immunosuppression, Daya and Ilari19 reported more favorable results than previously published following living-related conjunctival limbal allograft20 in their mixed cohort of 10 eyes. After a mean follow-up of 26.2 months, 80% of eyes (8/10) achieved successful reepithelialization, 80% (8/10) had decreased corneal vascularization, and 100% of eyes (5/5) experienced symptomatic relief of pain. BCVA improved in 70% (7/10) and was unchanged in 30% of eyes (3/10). However, in 3 of 7 eyes, conjunctivalization recurred and in 6 of 10 eyes, corneal opacity remained evident at last follow-up. Holland3 reported on a mixed series of 25 eyes with an average of 26.4 months following keratolimbal allograft with systemic immunosuppression. A stable ocular surface was achieved in 72% of eyes (18/25) and an improvement in 2 lines or greater was achieved in 60% of eyes (15/25). A relatively meaningful comparison may exist between limbal stem cell transplantation outcomes in severe contact lens wear–related and aniridia-related limbal stem cell deficiency, as they are both classified as stage AII diseases where the conjunctiva is relatively normal without inflammation.6 In their homogenous cohort of 31 eyes with aniridic keratopathy undergoing keratolimbal allograft, Holland and associates21 showed a stable ocular surface in 74.2% of eyes (23/31) after a mean of 35.7 months follow-up. In addition, 87.1% of eyes (27/31) showed improvement in visual acuity. Despite the positive results in these studies, long-term reports of allogenic limbal stem cell transplantation with insufficient levels of systemic immunosuppression have shown attrition of the allogenic graft survival, ranging from 21.1% to 33.3% after 4 years of follow-up.22–24 VOL. 160, NO. 6
The excellent results achieved in our cohort of patients are likely a result of the combination of a rigorous immunosuppression regimen and the absence of any conjunctival inflammation in eyes with contact lens wear–related limbal stem cell deficiency. Limbal tissue contains Langerhans cells and sits on a well-vascularized bed, and thus is highly antigenic. Several studies have underscored the importance of systemic immunosuppression in the outcomes after limbal stem cell transplantation. Notably, in their aniridic cohort, Holland and associates21 found that following keratolimbal allograft, 90.5% of eyes (19/21) receiving systemic immunosuppression achieved a stable ocular surface vs only 40% of eyes (4/10) not receiving systemic immunosuppression. From least to most intensive, survival after allogeneic limbal stem cell transplant was reported at 23.7% at 5 years (cyclosporine only) by Solomon and associates,22 21.2% at 5 years (cyclosporine only) by Ilari and Daya,23 33.3% at 4 years (steroids, cyclosporine, and mycophenolate mofetil) by Han and associates,24 and 83% at 5 years (mycophenolate mofetil and tacrolimus) by Liang and associates.25 Numerous other differences exist between these studies and care should be taken in interpreting this trend. More recently, a comparison of number of HLA matches in limbal stem cell transplant by Reinhard and associates26 demonstrated that in the long-term survival of livingrelated conjunctival limbal allografts, 65% with 0 or 1 mismatched HLA markers survived at 5 years vs 41% of grafts with 2–6 mismatches and 14% of untyped grafts, further underscoring the role of immunogenicity. In our study, all patients received systemic prednisone, tacrolimus, and mycophenolate mofetil, which has previously been shown to be safe and effective in limbal stem cell transplantation.27 Previous evaluation of this regimen revealed severe adverse events in 1.5% of patients and minor adverse events (elevated creatinine, hypertension, diabetes, pneumonia, avascular necrosis) in 14% of patients, mostly related to tacrolimus. In our cohort, this immunosuppression protocol was generally well tolerated. Two patients experienced side effects associated with Bactrim prophylaxis use. Of those, 1 patient experienced elevated bilirubin levels, which resolved with cessation of the drug; the other patient developed neutropenia, which resolved with cessation and treatment with G-CSF. A third patient experienced nonspecific nausea, which was treated effectively with antiemetics. A common complication after limbal stem cell transplantation is an increase in intraocular pressure, with studies reporting rates of 33.1%,23 37.2%,28 and 37.5%.24 The cause of this may be due to the removal of fibrous tissue in the recipient eye, taking with it draining vessels responsible for the outflow of aqueous humor.28 In our study, we had a higher incidence of elevated intraocular pressure, with 57% of eyes (8/14) requiring topical antiglaucoma treatment. In addition, 71% of eyes (10/14) required subsequent cataract extraction, markedly higher than previously reported by Baradaran-Rafii and associates29 at 17.8%.
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In addition to immunogenicity, several other factors have been associated with poorer outcomes following limbal stem cell transplantation, including severe dry eye, keratinization, eyelid scarring, symblepharon, lagophthalmos, and inflammatory conditions.6,20,24 In contact lens wear–related limbal stem cell deficiency, the conjunctiva is relatively noninflamed. In more severe ocular surface disease where the conjunctiva has been previously or is still actively inflamed, appropriate sequential treatment of coexisting conditions must be taken before attempting any ocular surface stem cell transplantation. Higher incidences of graft failure have been reported by several studies of Stevens-Johnson syndrome patients, where persistent inflammation, fibrosis, and tear film abnormalities create an unfavorable environment and contribute to persistent stem cell exhaustion.22,30,31 In our 1 patient (2 eyes) that achieved only an improved ocular surface, with areas of healthy cornea and areas of abnormal conjunctival epithelium, the patient suffered from significant rosacea blepharokeratoconjunctivitis. Interestingly, keratolimbal allograft surgery was performed in this patient owing to lack of living-donor availability. A procedure using tissue from a live donor may have potentially conferred more benefit to this patient by providing healthy donor conjunctiva with goblet cells as well. Contemporary limbal stem cell transplantation techniques for bilateral disease have evolved to include the use of ex vivo culture methods that are associated with their own advantages and disadvantages. Variability in inclusion criteria, source of cells, substrates and culture techniques, and immunosuppression methods exist. Despite this, Baylis and associates32 found no significant difference in the clinical outcomes of culture limbal epithelial transplantation regardless of culture technique, donor tissue, and indication. For allogenic procedures, they reported a 77% overall success rate, most commonly defined as a fully epithelialized and avascular cornea, in their systemic review including 93 cases. Other options for bilateral limbal stem cell deficiency include alternative tissue sources, of which only oral mucosal epithelium has been investigated in humans.33 Practically, the high cost of establishing and maintaining an ex vivo stem cell laboratory limit their applicability to only a few tertiary centers worldwide.34 In the last few years, a new technique, simple limbal epithelial transplantation, wherein limbal stem cells are expanded in vivo over an amniotic membrane placed over the surface of a cornea, has been reported in
the literature, showing promising results.35 So far, this procedure has primarily been performed using autologous tissue. However, 1 case report exists that demonstrated acceptable visual outcomes in a case of allogenic simple limbal epithelial transplantation.36 Of note, graft rejection occurred at 4 months, which was managed successfully with steroids but caused the authors to conclude that a more aggressive immunosuppresion regimen may be required. Limitations of this study include its retrospective nature and the limited sample size. Also, although impression cytologic analysis has been used in other studies to diagnose limbal stem cell deficiency, it was not performed on the patients in this series. Clinical findings on slit-lamp examination of late fluorescein staining and the hazy, thickened abnormal epithelium progressive from the limbus that did not resolve with supportive therapy are hallmark clinical signs of limbal stem cell deficiency. In addition, pathologic analysis of the corneal pannus removed during the surgeries indicated presence of conjunctival goblet cells, which is diagnostic for the conjunctivalization of the corneal surface that occurs in limbal stem cell deficiency. Because of sample size, subgroup analysis between the 2 techniques was not possible. Nevertheless, this study represents the largest series reported in the literature of a homogenous cohort of severe subtotal-total limbal stem cell deficiency, related to contact lens wear, treated with limbal stem cell transplantation. We are able to show promising outcomes in these patients who have failed conservative treatment and where traditional corneal transplant would not be appropriate. It is important for ophthalmologists to recognize this condition and the treatment options available, including surgery. In conclusion, limbal stem cell transplantation with systemic immunosuppression is a viable surgical option for these young and otherwise healthy patients presenting with severe contact lens wear–related limbal stem cell deficiency. Early intervention prior to the development of subepithelial fibrosis can lead to symptom relief and excellent visual outcomes without the need for subsequent corneal transplant. Monitoring for intraocular pressure elevation and cataract formation secondary to topical immunosuppression is important. Co-management with a transplant specialist is helpful for the monitoring and management of systemic adverse effects. Further studies are required to examine the long-term outcomes of living and cadaver transplanted tissue in these patients.
FUNDING/SUPPORT: NO FUNDING OR GRANT SUPPORT. FINANCIAL DISCLOSURES: CLARA C. CHAN HAS RECEIVED HONORARIA from Allergan (Irvine, California), Bausch & Lomb (Bridgewater, New Jersey), Alcon Laboratories Inc (Fort Worth, Texas), and Tearscience (Morrisville, North Carolina). Edward J. Holland has consulted for Alcon Laboratories Inc (Fort Worth, Texas), Bausch & Lomb (Bridgewater, New Jersey), Kala Corporation (Waltham, Massachusetts), Mati Therapeutics (Austin, Texas), PRN (Plymouth Meeting, Pennsylvania), RPS (Fort Washington, Philadelphia), Senju Pharmaceuticals (Woodland Hills, California), Tearscience (Morrisville, North Carolina), and TearLab (San Diego, California). The following author has no financial disclosures: Carl Shen. All authors attest that they meet the current ICMJE criteria for authorship.
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REFERENCES 1. Huang AJ, Tseng SC. Corneal epithelial wound healing in the absence of limbal epithelium. Invest Ophthalmol Vis Sci 1991;32(1):96–105. 2. Shapiro MS, Friend J, Thoft RA. Corneal re-epithelialization from the conjunctiva. Invest Ophthalmol Vis Sci 1981;21(1): 135–142. 3. Holland EJ. Epithelial transplantation for the management of severe ocular surface disease. Trans Am Ophthalmol Soc 1996; 94(1):677–743. 4. Huang AJ, Tseng SC, Kenyon KR. Alteration of epithelial paracellular permeability during corneal epithelial wound healing. Invest Ophthalmol Vis Sci 1990;31(3):429–435. 5. Puangsricharern V, Tseng SC. Cytologic evidence of corneal diseases with limbal stem cell deficiency. Ophthalmology 1995; 102(10):1476–1485. 6. Holland EJ, Schwartz GS. The evolution of epithelial transplantation for severe ocular surface disease and a proposed classification system. Cornea 1996;15(6):549–556. 7. Chan CC, Holland EJ. Severe limbal stem cell deficiency from contact lens wear: patient clinical features. Am J Ophthalmol 2013;155(3):544–549. 8. Jeng BH, Halfpenny CP, Meisler DM, Stock EL. Management of focal limbal stem cell deficiency associated with soft contact lens wear. Cornea 2011;30(1):18–23. 9. Croasdale CR, Schwartz GS, Malling JV, Holland EJ. Keratolimbal allograft: recommendations for tissue procurement and preparation by eye banks, and standard surgical technique. Cornea 1999;18(1):52–58. 10. Daya SM, Holland E, Mannis M. Ocular Surface Disease Medical and Surgical Management. New York: SpringerVerlag; 2002. 11. Biber JM, Skeens HM, Neff KD, Holland EJ. The Cincinnati procedure: technique and outcomes of combined living-related conjunctival limbal allografts and keratolimbal allografts in severe ocular surface failure. Cornea 2011;30(7):765–771. 12. Kim BY, Riaz KM, Bakhtiari P, et al. Medically reversible limbal stem cell disease: clinical features and management strategies. Ophthalmology 2014;121(10):2053–2058. 13. Clinch TE, Goins KM, Cobo LM. Treatment of contact lensrelated ocular surface disorders with autologous conjunctival transplantation. Ophthalmology 1992;99(4):634–638. 14. Bloomfield SE, Jakobiec FA, Theodore FH. Contact lens induced keratopathy: a severe complication extending the spectrum of keratoconjunctivitis in contact lens wearers. Ophthalmology 1984;91(3):290–294. 15. Bhatia RP, Srivastava R, Ghosh A. Limbal stem cell study in contact lens wearers. Ann Ophthalmol (Skokie) 2009;41(2):87–92. 16. Martin R. Corneal conjunctivalisation in long-standing contact lens wearers. Clin Exp Optom 2007;90(1):26–30. 17. Jenkins C, Tuft S, Liu C, Buckley R. Limbal transplantation in the management of chronic contact-lens-associated epitheliopathy. Eye (Lond) 1993;7(5):629–633. 18. Tan DT, Ficker LA, Buckley RJ. Limbal transplantation. Ophthalmology 1996;103(1):29–36. 19. Daya SM, Ilari FA. Living related conjunctival limbal allograft for the treatment of stem cell deficiency. Ophthalmology 2001;108(1):126–133.
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20. Rao SK, Rajagopal R, Sitalakshmi G, Padmanabhan P. Limbal allografting from related live donors for corneal surface reconstruction. Ophthalmology 1999;106(4):822–828. 21. Holland EJ, Djalilian AR, Schwartz GS. Management of aniridic keratopathy with keratolimbal allograft: a limbal stem cell transplantation technique. Ophthalmology 2003; 110(1):125–130. 22. Solomon A, Ellies P, Anderson DF, et al. Long-term outcome of keratolimbal allograft with or without penetrating keratoplasty for total limbal stem cell deficiency. Ophthalmology 2002;109(6):1159–1166. 23. Ilari L, Daya SM. Long-term outcomes of keratolimbal allograft for the treatment of severe ocular surface disorders. Ophthalmology 2002;109(7):1278–1284. 24. Han ES, Wee WR, Lee JH, Kim MK. Long-term outcome and prognostic factor analysis for keratolimbal allografts. Graefes Arch Clin Exp Ophthalmol 2011;249(11):1697–1704. 25. Liang L, Sheha H, Tseng SCG. Long-term outcomes of keratolimbal allograft for total limbal stem cell deficiency using combined immunosuppressive agents and correction of ocular surface deficits. Arch Ophthalmol 2009;127(11): 1428–1434. 26. Reinhard T, Spelsberg H, Henke L, et al. Long-term results of allogeneic penetrating limbo-keratoplasty in total limbal stem cell deficiency. Ophthalmology 2004;111(4):775–782. 27. Holland EJ, Mogilishetty G, Skeens HM, et al. Systemic immunosuppression in ocular surface stem cell transplantation: results of a 10-year experience. Cornea 2012;31(6):655–661. 28. Tsubota K, Shimmura S, Shinozaki N, Holland EJ, Shimazaki J. Clinical application of living-related conjunctival-limbal allograft. Am J Ophthalmol 2002;133(1):134–135. 29. Baradaran-Rafii A, Eslani M, Djalillian AR. Complications of keratolimbal allograft surgery. Cornea 2013;32(5):561–566. 30. Maruyama-Hosoi F, Shimazaki J, Shimmura S, Tsubota K. Changes observed in keratolimbal allograft. Cornea 2006; 25(4):377–382. 31. Santos MS, Gomes JAP, Hofling-Lima AL, Rizzo LV, Romano AC, Belfort R. Survival analysis of conjunctival limbal grafts and amniotic membrane transplantation in eyes with total limbal stem cell deficiency. Am J Ophthalmol 2005;140(2):223–230. 32. Baylis O, Figueiredo F, Henein C, Lako M, Ahmad S. 13 years of cultured limbal epithelial cell therapy: a review of the outcomes. J Cell Biochem 2011;112(4):993–1002. 33. Burillon C, Huot L, Justin V, et al. Cultured autologous oral mucosal epithelial cell sheet (CAOMECS) transplantation for the treatment of corneal limbal epithelial stem cell deficiency. Invest Ophthalmol Vis Sci 2012;53:1325–1331. 34. Miri A, Al-Deiri B, Dua HS. Long-term outcomes of autolimbal and allolimbal transplants. Ophthalmology 2010;117(6): 1207–1213. 35. Sangwan VS, Basu S, MacNeil S, Balasubramanian D. Simple limbal epithelial transplantation (SLET): a novel surgical technique for the treatment of unilateral limbal stem cell deficiency. Br J Ophthalmol 2012;96(7):931–934. 36. Bhalekar S, Basu S, Sangwan VS. Successful management of immunological rejection following allogeneic simple limbal epithelial transplantation (SLET) for bilateral ocular burns. BMJ Case Rep. http://dx.doi.org/10.1136/bcr.2013.009051.
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Biosketch Carl Shen, BMSc, is currently a fourth-year medical student at the University of Toronto, Ontario, Canada. He has been involved in a variety of research projects at the Harvard Stem Cell Institute, TLC Laser Eye Centre, Toronto Western Research Institute, and the Hospital for Sick Children.
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