ARTICLE

PROSE for Irregular Corneas at a Tertiary Eye Care Center Amudha Oli Arumugam,

M.Phil.Optom., FIACLE,

Rajni Rajan, M.Phil.Optom., Madhumathi Subramanian, and Rajeswari Mahadevan, Ph.D.Optom., FIACLE.

Objective: The aim of this study was to report and discuss the clinical experience with PROSE (Prosthetic Replacement of Ocular Surface Ecosystem) practice at a tertiary eye care hospital. Methods: Retrospective data of patients who were prescribed PROSE during April 2011 to March 2012 in a tertiary eye care center in south India were analyzed. Data collected include patient demographics, indications of scleral lens fitting, previous correction modality, PROSE parameters, bestcorrected visual acuity (BCVA) with spectacles, and BCVA with PROSE at initial assessment and few hours of wear. The BCVA before (with glasses) and after PROSE fitting was recorded in logMAR units. Results: The age of the patients ranged between 13 and 68 years (male: female 60:25) with a mean age of 32.44613.45 years. Mean BCVA improved by 0.3 logMAR units (3 lines) after fitting with PROSE. There was a statistically significant difference between pre- and post-PROSE BCVA (P=0.0001). Failure of rigid gas-permeable lens fitting or intolerance was the common indication for PROSE in corneas with irregular astigmatism (refractive conditions). The other reasons for which PROSE was prescribed were pain, photophobia, comfort, ghosting of images, and frequent loss of smaller lenses. Toric scleral haptic was indicated in 62 eyes. The diameter, vault, and haptic measurements of PROSE in ocular surface disorders were much less and flatter than that of refractive conditions. Conclusions: PROSE device is a very useful alternative for irregular corneas to improve visual acuity, to improve comfort, and for symptomatic relief. Key Words: PROSE—Ocular surface disorders—Irregular cornea—scleral lens—keratoconus—scleral toricity. (Eye & Contact Lens 2014;40: 71–73)

T

he Prosthetic Replacement of Ocular Surface Ecosystem (PROSE), also called as Boston ocular surface prosthesis, is a scleral lens that was approved by the Food and Drug Administration in 1994 for the management of corneal disorders. Initially, PROSE was perceived as a means of correcting astigmatism in irregular corneas. Fluid-ventilated and gas-permeable scleral lens have proved to be a valuable therapeutic tool in the management of severe ocular surface disorders (OSD).1,2 The PROSE is a gaspermeable scleral lens that vaults the cornea and submerges the entire corneal surface in a pool of oxygenated tears.1,2 From the Contact Lens Department, Medical Research Foundation, Sankara Nethralaya, Chennai, India. The authors have no funding or conflicts of interest to disclose. Address correspondence to Rajeswari Mahadevan, Ph.D.Optom., FIACLE, Medical Research Foundation, Sankara Nethralaya, No 18, College road, Nungambakkam, Chennai 600006, India; e-mail: [email protected] Accepted October 24, 2013. DOI: 10.1097/ICL.0000000000000006

Eye & Contact Lens  Volume 40, Number 2, March 2014

B.S.Optom.,

Each device is custom designed and manufactured using computer-aided design and computer-aided manufacturing (CAD/ CAM) technology linked to a high-precision, high-resolution computerized lathe.1–3 The fitting characteristics of the lens, including corneal vault, haptic fitting relationship, absence of lens suction or intrusion of air bubbles, and quality of vision, are evaluated after it has settled on the eye.2 PROSE has been found to be effective in improving quality and quantity of vision in patients with irregular astigmatism resulting from several corneal and ocular surface conditions, who had not responded satisfactorily to conventional methods of optical correction.1–5 The hallmark of OSD, except in neurotrophic cornea, is pain and photophobia, which can be as severe and unremitting as to be more disabling than visual impairment. Intractable pain, disabling photophobia, and recurrent or persistent corneal erosions or ulceration that can lead to corneal melting and corneal perforation are the signatures of many of these diseases that include severe dry eye, stem cell–deficient cornea, neurotrophic cornea, exposure, and corneal disorder associated with certain dermatologic epidermal diseases. By immersing the corneal surface in a bubble-free pool of oxygenated artificial tears, the fluid-ventilated gas-permeable scleral lens has expanded the management of OSD.2,3,5–7 PROSE device is used for a wide range of clinical conditions at our facility. Because of the nature of fitting requirements, facility required, and cost involved, PROSE practice is limited to few tertiary centers. Our facility being one among the large practices for PROSE, it is worthwhile to discuss the use of PROSE in our clinical scenario. Thus, the aim of our study was to report and discuss the clinical experience with PROSE practice at a tertiary eye care hospital.

METHODS Retrospective data of patients who were prescribed PROSE for the period of April 2011 to March 2012 in a tertiary eye care center in south India were analyzed. The internal review board of our institution approved our study, informed consent was obtained from patients, and the study followed the tenets approved by the Declaration of Helsinki. The data collected include patient demographics, indications of scleral lens fitting, previous correction modality, PROSE parameters, best-corrected visual acuity (BCVA) with spectacles, and PROSE. PROSE fit with different trial devices was assessed at 1-, 3-, and 6-hour intervals, and final PROSE was ordered using CAD/CAM software. The vault-control spline provides a precise and predictable mechanism for adjusting the corneal clearance independently of the base curve and internal optical zone. The optimal corneal apical clearance was considered to be 100 to 200 mm,1,2,5 although in this set of patients and particularly in some advanced irregular 71

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Eye & Contact Lens  Volume 40, Number 2, March 2014

A. O. Arumugam et al. TABLE 1.

Diagnoses and Indications of PROSE

Diagnosis

No. Eyes

Refractive group Keratoconus Penetrating keratoplasty Radial keratotomy Keratoglobus High astigmatism Ocular Surface Disorders Nonclinical dry eye Stevens–Johnson syndrome Dry eye Total

56 4 5 2 1 2 13 2 85

corneas, the highest clearance was greater than 200 mm. The fitting relationship of the posterior haptic surface is determined by observing the blanching pattern of the underlying bulbar conjunctiva. The objective was to avoid creating a complete ring of compression that seals the fluid compartment and promotes lens suction. The BCVA with glasses and PROSE was recorded in logMAR units. Vision was tested with the optimally fitting PROSE at initial assessment and after 4 to 6 hours of wear. The demographic details and final PROSE parameters were analyzed using SPSS version 17. The data were nonparametric. Thus, Wilcoxon signed-rank test was used to analyze statistically significant differences of pre- and post-PROSE fitting. A P value less than 0.05 was considered statistically significant.

RESULTS Eighty-five eyes of 63 patients were fitted with PROSE. The primary reasons for PROSE fitting were refractive conditions and OSD in 68 and 17 eyes, respectively. The details of the category of conditions are shown in Table 1. The age of the patients ranged between 13 and 68 years (male:female 60:25) with a mean age of 32.44613.45 years. The BCVA in logMAR units with glasses and PROSE is shown in Table 2. Mean BCVA improved by 0.3 logMAR units (3 lines) after fitting with PROSE. There was a statistically significant difference between pre- and post-PROSE BCVA (Table 2). The previous corrective modalities and the reasons for opting for PROSE are elucidated in Figures 1 and 2. Failure of gas-permeable lens fitting or intolerance was the common indication for PROSE in irregular corneas. The other reasons for which PROSE was prescribed were pain, photophobia, comfort, ghosting of images, and frequent loss of smaller lenses. The previous corrective modalities ranged from no correction, rigid gas permeable (RGP), special design RGP, piggyback, hybrid, and fenestrated sclerals. In the refractive group, 4.76% (7/68 eyes) opted for PROSE without the use of any other visual aids. TABLE 2.

Diagnosis Irregular corneas (n=85) Refractive group (n=68) OSD group (n=17)

BCVA With Glasses and PROSE BVCA With Glasses (Mean6SD) (logMAR units)

BVCA With PROSE (Mean6SD) (logMAR units)

P

0.5160.42 0.4560.34 0.7460.63

0.2360.30 0.1760.16 0.4460.52

0.0001 0.0001 0.007

Best-corrected visual acuity (BCVA) with glasses and Prosthetic Replacement of Ocular Surface Ecosystem (PROSE) in Irregular Corneas: refractive group and ocular surface disorders (OSD).

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FIG. 1. Previous correction modalities in PROSE patients. RGP, rigid gas-permeable lens.

Most of the patients in the OSD category (13/17 eyes) were diagnosed with Stevens–Johnson syndrome (SJS) and were referred for PROSE because of disabling symptoms of photophobia and pain. One patient (both eyes) experienced neuropathic pain and photophobia without any clinical signs of dry eye (nonclinical dry eye).8 The vault of PROSE ranged from 4.5 to 7.2 mm, with a mean of 5.2660.43 mm. In OSD, the vault ranged from 4.5 to 5.3 mm, with a mean of 4.960.25 mm. The haptic curvature ranged from 13 to 21 mm, with a mean of 14.7360.98 mm. The flattest haptic curve radius required was 21 and 17 mm in the OSD and refractive groups, respectively. The diameter of PROSE ranged from 17 to 20.5 mm, with a mean of 19.1560.56 mm. In OSD, the diameter used was between 17 and 22.5 mm. More than 50% of the eyes (62 eyes) required toric haptic; 32, 6, and 47 eyes were fitted with 0, 0.3, and 0.6 front surface eccentricity, respectively.

DISCUSSION The two primary reasons for PROSE are for masking corneal front surface irregular astigmatism and in managing symptoms of severe OSD.1–4 In our practice, we have prescribed PROSE for conditions such as keratoconus, status post-penetrating keratoplasty, status post-radial keratotomy, keratoglobus, pellucid marginal degeneration, SJS, and dry eye. Although pediatric PROSE fitting is challenging because of the difficulty in fitting and training the patients/parents in lens handling, the age of the youngest patient in this study was 13 years. The age reported in previous literature on pediatric PROSE fitting by Gungor et al9 and Rathi et al10 ranged from 7 months to 12.92 years and 8 to 16 years, respectively. Similar to previous studies,1–4,6,11 this study showed significant improvement in BCVA with PROSE. The mean BCVA with glasses was 0.5160.42 logMAR units, which improved significantly with PROSE to 0.2360.30 logMAR units. Improvement in visual acuity was more in the refractive group than in the OSD group by 0.27 logMAR units. Because of pitfalls of retrospective data and reduced hours of wear in some ocular surface conditions due to debris or poor surface quality, there was a dearth of data about BCVA with PROSE after few hours of wear. In most of the eyes in the refractive group, the primary indication for PROSE was the failure of fitting of gas-permeable lenses or lens intolerance. In patients in the refractive group, PROSE provided better comfort because the cornea is not in contact with the lens and Eye & Contact Lens  Volume 40, Number 2, March 2014

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Eye & Contact Lens  Volume 40, Number 2, March 2014

PROSE for Irregular Corneas

FIG. 2. Percentage of reasons for selecting PROSE. RGP, rigid gas-permeable lens; CL, contact lens.

the large diameter prevents lens awareness while blinking. Therefore, patients with early or moderate degree of irregular corneas are also motivated to use PROSE. The reason for the relatively lower quantum of improvement of visual acuity in OSD could be the reduced ocular surface transparency in these eyes. The decrease in visual acuity over a period of PROSE wear during the day is due to collection of debris in the device surface and possible turbidity of the fluid reservoir. Therefore, the patients need to remove, clean, and replace the fluid after few hours of wear.4–7 Some patients are comfortable by cleaning the device surface with a cotton swab dipped in a compatible cleaning solution or saline. Meticulous care to the lid margins by way of frequent massage and cleaning and maintaining good lid hygiene helped in reducing the amount of debris formed on the device. The lens parameters varied with different conditions. The diameter, vault, and haptic measurements of PROSE in the OSD group were much less and flatter than those of the refractive group. Vault was sometimes higher, even up to 7.2 mm in ectatic corneas, especially in severe keratoconus and keratoglobus conditions. In OSD, the vault has to be increased only on corneas with dense scarring. Because of the nature of the condition and structural changes in the conjunctiva in the OSD group, the diameter was chosen to be smaller than in the refractive group. On the contrary, a patient with “nonclinical dry eye” was benefited only with a larger diameter device. In this case, the symptomatic relief was higher with the increased diameter of PROSE covering the ocular surface. Smaller diameter devices showed impingement in many patients during the fitting process, probably because of the irregular conjunctival surface in these eyes. It has been found that the smaller haptic bearing surface in smaller devices transmits greater compressive force on the sclera.5 Toric scleral haptic was indicated in 62 eyes. Eyes with toric scleras require greater haptic toricity in larger lenses than smaller lenses. Cicatricial conditions, such as SJS in which bulbar conjunctival scarring and symblepharon sometimes limit the available supporting surface, pose a unique challenge in the fitting of the PROSE device. Toric haptic is useful in such situations to prevent excessive edge lift or impingement.2,5,6 Previous studies have reported improved visual functions and decreased higher-order aberrations in subjects with irregular cornea fitted with PROSE device.12–14 Such studies have reported that measurement of ocular aberrations with different front surface eccentricity devices is important to decide on the best device for the eye.8–10 More patients with irregular corneas in our study pre-

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ferred front surface eccentricity design because it improved visual acuity and the quality of vision. Although this study does not quantify the change in ocular surface health, and relief of symptoms, PROSE device is a very useful alternative for patients with irregular corneas to improve visual acuity, to improve comfort, and for symptomatic relief. Although the fitting process, insertion, and removal may seem elaborate, the benefits it provides outweigh the hassle of intensive training given to patients. Further studies will elaborate how to overcome the challenges in fitting PROSE device and on the follow-up of patients with irregular corneas. REFERENCES 1. Rosenthal P, Cotter J. The Boston scleral lens in the management of severe ocular surface disease. Ophthalmol Clin North Am 2003;16:89–93. 2. Rosenthal P, Jacobs DS, Johns L. Fluid-ventilated gas permeable scleral lens: A new paradigm for the management of irregular corneal astigmatism and severe ocular surface disease. Contemp Ophthalmol 2006;5:1–7. 3. Stason WB, Razavi M, Jacobs DS, et al. Clinical benefits of the Boston ocular surface prosthesis. Am J Ophthalmol 2010;149:54–61. 4. Rathi VM, Mandathara PS, Dumpati S, et al. Boston ocular surface prosthesis: An Indian experience. Indian J Ophthalmol 2011;59:279. 5. Rosenthal P, Croteau A. Fluid-ventilated, gas-permeable scleral contact lens is an effective option for managing severe ocular surface disease and many corneal disorders that would otherwise require penetrating keratoplasty. Eye Contact Lens 2005;31:130–134. 6. Romero-Rangel T, Stavrou P, Cotter J, et al. Gas-permeable scleral contact lens therapy in ocular surface disease. Am J Ophthalmol 2000;130:25–32. 7. Lynette KJ. Fitting scleral lenses for ocular surface disease. Cont Lens Spectr 2011. Available at: http://www.clspectrum.com/articleviewer.aspx? articleid=105794. Accessed September 12, 2013. 8. Rosenthal P, Baran I, Jacobs DS. Corneal pain without stain: Is it real? Ocul Surf 2009;7:28–40. 9. Gungor I, Schor K, Rosenthal P, et al. The Boston scleral lens in the treatment of pediatric patients. J AAPOS 2008;12:263–267. 10. Rathi VM, Mandathara PS, Vaddavalli PK, et al. Fluid filled scleral contact lens in pediatric patients: Challenges and outcome. Cont Lens Anterior Eye 2012;35:189–192. 11. Dimit R, Gire A, Pflugfelder SC, et al. Patient ocular conditions and clinical outcomes using a PROSE scleral device. Cont Lens Anterior Eye 2013;36: 159–163. 12. Mahadevan R, Arumugam AO, Ganesan N, et al. Clinical visual performance of different front surface eccentricity in PROSE. Cont Lens Anterior Eye 2012;35:e6–e7. 13. Gumus K, Gire A, Pflugfelder SC. The impact of the Boston ocular surface prosthesis on wavefront higher-order aberrations. Am J Ophthalmol 2011; 151:682–690. 14. Hussoin T, Le HG, Carrasquillo KG, et al. The effect of optic asphericity on visual rehabilitation of corneal ectasia with a prosthetic device. Eye Contact Lens 2012;38:300–305.

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PROSE for irregular corneas at a tertiary eye care center.

The aim of this study was to report and discuss the clinical experience with PROSE (Prosthetic Replacement of Ocular Surface Ecosystem) practice at a ...
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