Explantation of posterior chamber lenses Francis W. Price, Jr., M.D., William E. Whitson, M.D., Karen Collins, R.N., Sharon Johns, L.P.N.
Intraocular lenses, in particular posterior chamber lenses, have dramatically affected the visual acuity and lifestyle of individuals after cataract surgery. Posterior chamber intraocular lens (IOL) implantation has become the standard of care for over one million routine cataract surgeries each year. 1 While some IOL styles have been associated with a high rate of complications and difficulties that require their explantation, posterior chamber lenses have shown few problems that require their removal. However, some do have to be removed and this study examines 119 of those lenses. MATERIALS AND METHODS All IOLs explanted by Corneal Consultants of Indiana from August 12, 1982, through February 14, 1992, were reviewed. All surgeries were performed by one of two surgeons (F.W.P., W.E.W.). There were 1,202 IOLs removed during that period and 119 were posterior chamber lenses. These 119 cases were reviewed for the diagnosis necessitating explantation, the time from implantation to explantation, and the associated surgery and treatment at the time of explantation. Corneal Consultants of Indiana is a major referral center for IOL complications in Indiana and some surrounding areas. The large number of explanted lenses reflects this.
RESULTS The mean time from implantation to removal of the 119 posterior chamber lenses was 21 months, with a range ofless than one month to 125 months. The mean age of the patients at the time of explantation was 69 years, with a range of four to 92. Table 1 shows the associated surgery that occurred at the time of explantation. Seventy (58.8%) of the lenses in this study were removed because of decentration or dislocation. Nineteen of them were completely dislocated into the vitreous cavity; five lay on the retinal surface or the macula itself. Eight lenses were partially dislocated into the vitreous; the haptic of one hung on the inferior margin of the pupil and later dislocated back onto the retina when the patient was laid flat on his back for explantation surgery. Four posterior chamber lenses were dislocated inferiorly in the sunset syndrome; at the time of explantation there was no evidence of remaining capsule material so they had apparently been implanted on the hyaloid face. All but one of the complete or partial dislocations into the vitreous occurred after canopener-type capsulotomies in which the capsule became unstable. One case occurred after capsulorhexis and later tearing of the posterior capsule. Two lenses were placed backward within the eye, causing them to bulge through the pupil from
Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, Boston, April 1991. Reprint requests to Francis W. Price, Jr., M.D., 9002 North Meridian Street, Suite 100, Indianapolis, Indiana 46260.
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER 1992
475
Table 1. Associated surgical procedures at the time of explantation. Pars plana vitrectomy Anterior vitrectomy Penetrating keratoplasty Iris repair Injection of intraocular antibiotics
49 32 18 14 8
Molteno implant Removal of retained cataract material Nolens replacement
1 9
20 97
Intraocular lens exchange with posterior chamber lens Sulcus-fixated on capsular remnants Iris fixated Scleral fixated
49 42 8
their normal ten-degree angulation. Haptic problems resulted in improper centration and fixation of 11 IOLs which then had to be removed. A Cilco one-piece poly(methyl methacrylate) (PMMA) lens dislocated six months after implantation because one haptic completely broke off near the optic. In four cases, capsule compression produced unequal bending of one haptic, causing the lens to decenter
and become loosely fixated. In these cases one haptic had apparently popped out of the capsular bag while the other had been compressed and lost its elastici ty. In seven cases with compressed haptics the haptic diameters ranged from 11 mm to 12 mm and were not sufficient to provide firm fixation within the ciliary sulcus. This allowed the windshield-wiper syndrome or even propellering around the posterior chamber. These loosely fixated lenses behaved similarly to rigid anterior chamber lenses that were too small for the anterior chamber. These difficulties occurred with both PMMA and polypropylene haptics. Table 2 describes these seven lenses. In two patients with loosely fixated lenses that had normal haptic diameters of 13.5 mm, the horizontal white-to-white diameters were 13.0 mm and 13.75 mm. In these two cases (Table 2), there was no way to place standard sized posterior chamber lenses and get firm sulcus fixation. In one case the lens was sutured to the posterior iris, and in the other, to the sclera. The posterior capsule remained in both cases. In two other cases with normal horizontal white-to-white diameters of 12.0 mm and 12.25 mm, lenses with 12.5 mm diameters did not achieve sulcus fixation. In each of these cases the surgeon attempted to place the lens in the capsular bag.
Table 2. Cases in which the haptic size was insufficient for sulcus fixation.
Type of IOL
Time of Removal*
Original Size
Horizontal Corneal Diameter (mm)
ORC UV31A2 CooperVision 876-06 Coburn 127UV
12.00
13.50
Unknown
12.00
14.00
Unknown
Immediately
14
11.50
13.75
Unknown
Immediately
5
ORC UV40F9 Surgidev B25 Alcon MZ20BD Pharmacia 810F
11.25
14.00
Unknown
21
11.00
14.00
12.50
15
12.25
12.50
12.25
12.00
12.00
12.00
Haptic Diameter (mm)
Months Postimplantation Symptoms 1
Explantation 7
Haptic Material Blue Prolene
Axial Length (mm) 30.27
PMMA
24.75
Blue Prolene
23.20
21
PMMA
24.14
23
PMMA
24.68
Immediately
1
PMMA
26.06
Immediately
2
PMMA
27.06
ORC 13.50 14.00 13.75 Immediately UV40R4 CooperVision 13.50 14.00 13.00 Immediately 425.01 ... Measured with calipers by surgeon (FWP) at the time of explantation.
72
Blue Prolene
26.52
35
Blue Prolene
25.80
476
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER 1992
Of the 119 explanted posterior chamber lenses, 15 (12.6%) were removed for anisometropia, 18 for chronic inflammation, eight for chronic endophthalmitis, three for acute endophthalmitis, three for trauma, and two for YAG laser damage. Anisometropia can usually be prevented by improved techniques with A-scan calculations. However, eight of the 15 IOLs explanted for anisometropia were from eyes that had penetrating keratoplasty. In these eight cases, the cornea developed unpredicted corneal curvatures. Another preventable cause of removal involved two patients with severe lens damage after YAG laser capsulotomy, resulting in immediate loss of vision that was correctable only by IOL removal. We do not routinely remove dislocated posterior chamber lenses secondary to trauma if they can be treated and replaced within the eye nor do we routinely remove IOLs because of acute or chronic endophthalmitis. However, in this series, there were situations in which we could not replace the traumatized posterior chamber lens: In two cases, the iris was totally lost, as was the capsular material. In three cases of acute endophthalmitis there was no possibility oflong-term IOL stability because of
the degenerative changes that had occurred. The IOLs were removed at the time of pars plana vitrectomy and intraocular antibiotic injection. Four of the eight cases of chronic endophthalmitis had been treated with intraocular antibiotics; one of these cases has been reported. 2 Table 3 describes the eyes with chronic endophthalmitis from which IOLs were explanted. DISCUSSION Posterior chamber lenses represent 9.9% of the IOLs removed in our practice over the last nine years. This is a relatively small percentage, considering these lenses represent over 95% of the IOLs implanted at this time. l In our series the average time between implantation and removal of posterior chamber lenses was 21 months; it was 102 months for iris-fixated lenses, 94 months for rigid anterior chamber lenses, and 56 months for closed-loop anterior chamber lenses. We believe that design limitations necessitated the removal of most of the anterior chamber and older-style irisfixated lenses. While there have been some difficulties with posterior chamber lens designs, the
Table 3. Cases in which the lenses were explanted for chronic endophthalmitis. Months from Implantation
Years of Age SympPatient (months) toms
Explantation
Previous Treatment
Methods of Diagnosis
Organism Found
1
79
5
13
Topical anti-inflammatory PPV cultures, inject intraocular antibiotics
Pars plana vitrectomy C & S* of vitreous
Rare gram negative rods
2
74
6
16
None
Pars plana vitrectomy C & S of vitreous
Few Corynebacterium species, Flavobacterium species
3
74
13
16
Inject intraocular antibiotics
Pars plana vitrectomy C & S of vitreous
Propionibacterium acnes
4
71
3
14
Inject intraocular antibiotics
Pars plana vitrectomy C & S of vitreous
Coag negative Staphylococcus
5
87
12
38
None
C & S of vitreous
Flavobacterium series, Pseudomonas paucimobilis, Pseudomonas diminuta
6
78
2
14
Inject intraocular antibiotics
Pars plana vitrectomy C & S of vitreous
Rare gram positive cocci
7
81
40
42
None
Propionibacterium acnes
8
81
Immediate
6
None
Pars plana vitrectomy Removal of IOL & capsule C & S of vitreous Anterior vitrectomy
Coag negative Staphylococcus
* Culture and sensitivity
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER
1992
477
removal of posterior chamber lenses has been necessitated primarily by surgical technique or extraneous causes such as infection or trauma. Solomon et al. 3 found that posterior chamber lenses were most frequently explanted because of decentration or malpositioning. Many of the removed lenses in our series fit into a category that may be preventable with changes in the original cataract implantation technique, such as capsulorhexis instead of a can-opener capsulotomy or inthe-bag placement instead of sulcus/zonular placement. We are not suggesting that surgery was done improperly. In many cases the surgery was done in the accepted manner. The can-opener-style anterior capsulotomy was the accepted and most routine method until recently. However, that particular type of capsulotomy can lead to inadvertent tears in the capsule out to the equator and sometimes beyond. Problems with decentration or asymmetrical fixation of posterior chamber lenses after can-opener-type capsulotomies has been demonstrated in postmortem eyes. 4 In these cases, especially as contraction occurs, the IOL haptics can pop out of the capsular bag or the capsule can be weakened and the IOL can actually dislocate back into the posterior portion of the eye. This appears to have contributed to or caused a majority of our dislocated lenses (62 lenses, 52.1 %). Using a continuous tear capsulotomy technique should eliminate the dislocations if the IOL is placed in the capsular bag. However, we encountered one case in which a continuous tear capsulotomy was performed, yet defects in the posterior capsule led to IOL loss into the vitreous. An advantage of capsulorhexis is the potential of placing a lens on the anterior capsule when the posterior capsule tears. However, one must select a lens whose diameter is adequate for sulcus fixation . Another advantage of capsulorhexis is that the surgeon has a good view of the remaining anterior capsule because of the contrast between the opening centrally inside the capsulorhexis and the outer capsule. Four of our cases of sunset syndrome had no demonstrable capsular material for support,and apparently the IOLs had been placed on the hyaloid face. These lenses dislocated immediately after implantation. The can-opener technique can lead to situations in which the anterior capsule may not be visible behind a mid-dilated pupil, and its edges may be difficult to see even if the iris is retracted. These four cases might have been avoided if a clearly demarcated capsulorhexis had been performed and the surgeon had been aware that capsule was no longer present. Mansour and 478
coauthors 5 reported placement of an IOL in the ciliary sulcus on the hyaloid face in one case in which there was still posterior capsule present anterior to the IOL; it is not clear whether the hap tics were entangled in the peripheral capsular material or the iris. Flynn and coauthors6 reported that dislocated IOLs in the vitreous cavity can, after extended periods, cause secondary complications such as retinal detachment and cystoid macular edema. We agree that these lenses should be removed. Furthermore, many times these individuals cannot see clearly (1) if the lens bisects the pupillary area or (2) if they are left aphakic and are unable to wear contact lenses. We would be reluctant to place a new IOL in an eye with a dislocated lens left in place. There have been other reports on exchanging or repositioning posterior chamber IOLs.6-12 We agree with Nabors and coauthors 7 that a pars plana vitrectomy is essential when suture fixating a posterior chamber lens, either to the ciliary sulcus area or the iris. In our experience this technique minimized later difficulties with vitreous traction around the IOL, or vitreous prolapse through the pupil, and potential difficulties related to the wound in which manipulation of the implant may have occurred through a limbal incision. In cases in which we fixate lenses to the iris with sutures we use a uniplanar lens. Previously placed lenses with angulated haptics can cause the peripheral haptic to push up against the peripheral iris when the lens is sutured to the iris. We have recently begun to fixate lenses to the sclera with sutures, and in those situations we prefer to have a lens that is specifically designed for that placement. We believe choosing the correct lens for implantation helps minimize difficulties with further dislocation or decentration. As these individuals have already had difficulty with a poorly fixated lens, we want to minimize the possibility of recurrence. One major question in repositioning posterior chamber lenses is whether the IOL can be placed on the remaining capsular material. One can be led into thinking there is sufficient capsular support present only to have the IOL dislocate, either during surgery or months later. While there is still no perfect technique for determining the extent of capsular support, we have found the use of a prototype endoscopic camera, manufactured by Alcon Surgical, to facilitate direct visualization of the zonular and capsular area. Without this camera, it is essentially impossible in the surgical setting to examine the peripheral area around the ciliary body.
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER
1992
Of the 15 lenses removed for anisometropia, eight were because of difficulties encountered after penetrating keratoplasty. Although advances in predicting the final keratometric results of corneal transplants have been made, this is still an area in which surprises are common to surgeons performing transplants. Occasionally, situations requiring that lenses be removed will develop. For patients who are not having a penetrating keratoplasty, new advances in axial length measurements may help minimize the occurrence of significant anisometropia. Laser damage should be avoidable by proper aiming, correct power setting on the laser, or by aborting the procedure in uncooperative patients. Dealing with the complications of endophthalmitis and chronic inflammation is more difficult. In four of the 18 cases with chronic inflammation the posterior chamber lens was partially or completely captured by the pupil, resulting in significant irritation and inflammation from iris contact with the haptics and sometimes the edges of the IOL optic. The continuous tear capsulotomy may minimize the occurrence of pupillary capture in which the pupil was originally anterior to the optic but gradually retracted posterior to the optic. In other cases it was difficult to diagnose the actual cause of the chronic inflammation. In some we suspected chronic endophthalmitis but were unable to culture an organism or to identify one in the removed pathologic specimens. In some cases, infection may have been present and been appropriately treated, only to have antigens or some other inflammatory material continue the chronic inflammation. Eyes with chronic endophthalmitis or chronic inflammation are very difficult to treat. The mean time from implantation to removal for chronic endophthalmitis was 17.5 months and for chronic inflammation, 34 months. The mean time from implantation to the occurrence of symptoms was 13 months for endophthalmitis and 20 months for inflammation. The occurrence of endophthalmitis after cataract surgery is so rare that it is difficult to devise specific guidelines to decrease its incidence. A higher incidence could occur with cataract surgery, considering the proximity of the eyelashes and external surface of the eye to the surgical procedure. Based on our experience, lens diameters should be greater than 12.0 mm to ensure good sulcus
fixation (Table 2). Three eyes had haptic diameters of 12.0 mm and two 12.5 mm, yet a windshieldwiper syndrome resulted. In two other cases, there were larger than normal corneal diameters, and even the 13.5 mm haptic diameter was insufficient. In one of these later patients, a lens placed in the capsular bag was well fixated in the other eye. If sulcus-fixation is attempted the horizontal whiteto-white diameter and axial length should be checked. Unusually large measurements for either of these could cause standard posterior chamber lenses to have inadequate sulcus fixation. In-thebag fixation offers the most reliable means of posterior chamber lens fixation. REFERENCES 1. Stark WJ, Sommer A, Smith RE. Changing trends in intraocular lens implantation (editorial). Arch Ophthalmol1989; 107:1441-1444 2. Tetz MR, Apple DJ, Price FW Jr, et al. A newly described complication of neodymium-YAG laser posterior capsulotomy: exacerbation of an intraocular infection. Arch Ophthalmol1987; 105:1324-1325 3. Solomon KD, Apple DJ, Mamalis N, et al. Complications of intraocular lenses with special reference to an analysis of 2500 explanted intraocular lenses (IOLs). Eur J Implant Refract Surg 1991; 3:195-200 4. Hansen SO, Tetz MR, Solomon KD, et al. Decentration of flexible loop posterior chamber intraocular lenses in a series of 222 postmortem eyes. Ophthalmology 1988; 95:344-349 5. Mansour A, Blodi CF, Yannis RA, Kimura AE. Intraocular lens placement behind the posterior capsule. Ophthalmic Surg 1990; 21:211-212 6. Flynn HW Jr, Buus D, Culbertson WW. Management of subluxated and posteriorly dislocated intraocular lenses using pars plana vitrectomy instrumentation. J Cataract Refract Surg 1990; 16:51-56 7. Nabors G, Varley MP, Charles S. Ciliary sulcus suturing of a posterior chamber intraocular lens. Ophthalmic Surg 1990; 21:263-265 8. Maguire AM, Blumenkranz MS, Ward TG, Winkelman JZ. Scleral loop fixation for posteriorly dislocated intraocular lenses; operative technique and long-term results. Arch Ophthalmol1991; 109:1754-1758 9. Stark WJ, Goodman G, Goodman D, Gottsch J. Posterior chamber intraocular lens implantation in the absence of posterior capsular support. Ophthalmic Surg 1988; 19:240-243 10. Smiddy WE. Dislocated posterior chamber intraocular lens: a new technique of management. Arch Ophthalmol 1989; 107:1678-1680 11. Doren GS, Stern GA, Driebe WT. Indications for and results of intraocular lens explantation. J Cataract Refract Surg 1992; 18:79-85 12. Eifrig DE. Two principles for repositioning intraocular lenses. Ophthalmic Surg 1986; 17:486-489
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER 1992
479
Intraocular lenses, in particular posterior chamber lenses, have dramatically affected the visual acuity and lifestyle of individuals after cataract surgery. Posterior chamber intraocular lens (IOL) implantation has become the standard of care for over one million routine cataract surgeries each year. 1 While some IOL styles have been associated with a high rate of complications and difficulties that require their explantation, posterior chamber lenses have shown few problems that require their removal. However, some do have to be removed and this study examines 119 of those lenses. MATERIALS AND METHODS All IOLs explanted by Corneal Consultants of Indiana from August 12, 1982, through February 14, 1992, were reviewed. All surgeries were performed by one of two surgeons (F.W.P., W.E.W.). There were 1,202 IOLs removed during that period and 119 were posterior chamber lenses. These 119 cases were reviewed for the diagnosis necessitating explantation, the time from implantation to explantation, and the associated surgery and treatment at the time of explantation. Corneal Consultants of Indiana is a major referral center for IOL complications in Indiana and some surrounding areas. The large number of explanted lenses reflects this.
RESULTS The mean time from implantation to removal of the 119 posterior chamber lenses was 21 months, with a range ofless than one month to 125 months. The mean age of the patients at the time of explantation was 69 years, with a range of four to 92. Table 1 shows the associated surgery that occurred at the time of explantation. Seventy (58.8%) of the lenses in this study were removed because of decentration or dislocation. Nineteen of them were completely dislocated into the vitreous cavity; five lay on the retinal surface or the macula itself. Eight lenses were partially dislocated into the vitreous; the haptic of one hung on the inferior margin of the pupil and later dislocated back onto the retina when the patient was laid flat on his back for explantation surgery. Four posterior chamber lenses were dislocated inferiorly in the sunset syndrome; at the time of explantation there was no evidence of remaining capsule material so they had apparently been implanted on the hyaloid face. All but one of the complete or partial dislocations into the vitreous occurred after canopener-type capsulotomies in which the capsule became unstable. One case occurred after capsulorhexis and later tearing of the posterior capsule. Two lenses were placed backward within the eye, causing them to bulge through the pupil from
Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, Boston, April 1991. Reprint requests to Francis W. Price, Jr., M.D., 9002 North Meridian Street, Suite 100, Indianapolis, Indiana 46260.
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER 1992
475
Table 1. Associated surgical procedures at the time of explantation. Pars plana vitrectomy Anterior vitrectomy Penetrating keratoplasty Iris repair Injection of intraocular antibiotics
49 32 18 14 8
Molteno implant Removal of retained cataract material Nolens replacement
1 9
20 97
Intraocular lens exchange with posterior chamber lens Sulcus-fixated on capsular remnants Iris fixated Scleral fixated
49 42 8
their normal ten-degree angulation. Haptic problems resulted in improper centration and fixation of 11 IOLs which then had to be removed. A Cilco one-piece poly(methyl methacrylate) (PMMA) lens dislocated six months after implantation because one haptic completely broke off near the optic. In four cases, capsule compression produced unequal bending of one haptic, causing the lens to decenter
and become loosely fixated. In these cases one haptic had apparently popped out of the capsular bag while the other had been compressed and lost its elastici ty. In seven cases with compressed haptics the haptic diameters ranged from 11 mm to 12 mm and were not sufficient to provide firm fixation within the ciliary sulcus. This allowed the windshield-wiper syndrome or even propellering around the posterior chamber. These loosely fixated lenses behaved similarly to rigid anterior chamber lenses that were too small for the anterior chamber. These difficulties occurred with both PMMA and polypropylene haptics. Table 2 describes these seven lenses. In two patients with loosely fixated lenses that had normal haptic diameters of 13.5 mm, the horizontal white-to-white diameters were 13.0 mm and 13.75 mm. In these two cases (Table 2), there was no way to place standard sized posterior chamber lenses and get firm sulcus fixation. In one case the lens was sutured to the posterior iris, and in the other, to the sclera. The posterior capsule remained in both cases. In two other cases with normal horizontal white-to-white diameters of 12.0 mm and 12.25 mm, lenses with 12.5 mm diameters did not achieve sulcus fixation. In each of these cases the surgeon attempted to place the lens in the capsular bag.
Table 2. Cases in which the haptic size was insufficient for sulcus fixation.
Type of IOL
Time of Removal*
Original Size
Horizontal Corneal Diameter (mm)
ORC UV31A2 CooperVision 876-06 Coburn 127UV
12.00
13.50
Unknown
12.00
14.00
Unknown
Immediately
14
11.50
13.75
Unknown
Immediately
5
ORC UV40F9 Surgidev B25 Alcon MZ20BD Pharmacia 810F
11.25
14.00
Unknown
21
11.00
14.00
12.50
15
12.25
12.50
12.25
12.00
12.00
12.00
Haptic Diameter (mm)
Months Postimplantation Symptoms 1
Explantation 7
Haptic Material Blue Prolene
Axial Length (mm) 30.27
PMMA
24.75
Blue Prolene
23.20
21
PMMA
24.14
23
PMMA
24.68
Immediately
1
PMMA
26.06
Immediately
2
PMMA
27.06
ORC 13.50 14.00 13.75 Immediately UV40R4 CooperVision 13.50 14.00 13.00 Immediately 425.01 ... Measured with calipers by surgeon (FWP) at the time of explantation.
72
Blue Prolene
26.52
35
Blue Prolene
25.80
476
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER 1992
Of the 119 explanted posterior chamber lenses, 15 (12.6%) were removed for anisometropia, 18 for chronic inflammation, eight for chronic endophthalmitis, three for acute endophthalmitis, three for trauma, and two for YAG laser damage. Anisometropia can usually be prevented by improved techniques with A-scan calculations. However, eight of the 15 IOLs explanted for anisometropia were from eyes that had penetrating keratoplasty. In these eight cases, the cornea developed unpredicted corneal curvatures. Another preventable cause of removal involved two patients with severe lens damage after YAG laser capsulotomy, resulting in immediate loss of vision that was correctable only by IOL removal. We do not routinely remove dislocated posterior chamber lenses secondary to trauma if they can be treated and replaced within the eye nor do we routinely remove IOLs because of acute or chronic endophthalmitis. However, in this series, there were situations in which we could not replace the traumatized posterior chamber lens: In two cases, the iris was totally lost, as was the capsular material. In three cases of acute endophthalmitis there was no possibility oflong-term IOL stability because of
the degenerative changes that had occurred. The IOLs were removed at the time of pars plana vitrectomy and intraocular antibiotic injection. Four of the eight cases of chronic endophthalmitis had been treated with intraocular antibiotics; one of these cases has been reported. 2 Table 3 describes the eyes with chronic endophthalmitis from which IOLs were explanted. DISCUSSION Posterior chamber lenses represent 9.9% of the IOLs removed in our practice over the last nine years. This is a relatively small percentage, considering these lenses represent over 95% of the IOLs implanted at this time. l In our series the average time between implantation and removal of posterior chamber lenses was 21 months; it was 102 months for iris-fixated lenses, 94 months for rigid anterior chamber lenses, and 56 months for closed-loop anterior chamber lenses. We believe that design limitations necessitated the removal of most of the anterior chamber and older-style irisfixated lenses. While there have been some difficulties with posterior chamber lens designs, the
Table 3. Cases in which the lenses were explanted for chronic endophthalmitis. Months from Implantation
Years of Age SympPatient (months) toms
Explantation
Previous Treatment
Methods of Diagnosis
Organism Found
1
79
5
13
Topical anti-inflammatory PPV cultures, inject intraocular antibiotics
Pars plana vitrectomy C & S* of vitreous
Rare gram negative rods
2
74
6
16
None
Pars plana vitrectomy C & S of vitreous
Few Corynebacterium species, Flavobacterium species
3
74
13
16
Inject intraocular antibiotics
Pars plana vitrectomy C & S of vitreous
Propionibacterium acnes
4
71
3
14
Inject intraocular antibiotics
Pars plana vitrectomy C & S of vitreous
Coag negative Staphylococcus
5
87
12
38
None
C & S of vitreous
Flavobacterium series, Pseudomonas paucimobilis, Pseudomonas diminuta
6
78
2
14
Inject intraocular antibiotics
Pars plana vitrectomy C & S of vitreous
Rare gram positive cocci
7
81
40
42
None
Propionibacterium acnes
8
81
Immediate
6
None
Pars plana vitrectomy Removal of IOL & capsule C & S of vitreous Anterior vitrectomy
Coag negative Staphylococcus
* Culture and sensitivity
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER
1992
477
removal of posterior chamber lenses has been necessitated primarily by surgical technique or extraneous causes such as infection or trauma. Solomon et al. 3 found that posterior chamber lenses were most frequently explanted because of decentration or malpositioning. Many of the removed lenses in our series fit into a category that may be preventable with changes in the original cataract implantation technique, such as capsulorhexis instead of a can-opener capsulotomy or inthe-bag placement instead of sulcus/zonular placement. We are not suggesting that surgery was done improperly. In many cases the surgery was done in the accepted manner. The can-opener-style anterior capsulotomy was the accepted and most routine method until recently. However, that particular type of capsulotomy can lead to inadvertent tears in the capsule out to the equator and sometimes beyond. Problems with decentration or asymmetrical fixation of posterior chamber lenses after can-opener-type capsulotomies has been demonstrated in postmortem eyes. 4 In these cases, especially as contraction occurs, the IOL haptics can pop out of the capsular bag or the capsule can be weakened and the IOL can actually dislocate back into the posterior portion of the eye. This appears to have contributed to or caused a majority of our dislocated lenses (62 lenses, 52.1 %). Using a continuous tear capsulotomy technique should eliminate the dislocations if the IOL is placed in the capsular bag. However, we encountered one case in which a continuous tear capsulotomy was performed, yet defects in the posterior capsule led to IOL loss into the vitreous. An advantage of capsulorhexis is the potential of placing a lens on the anterior capsule when the posterior capsule tears. However, one must select a lens whose diameter is adequate for sulcus fixation . Another advantage of capsulorhexis is that the surgeon has a good view of the remaining anterior capsule because of the contrast between the opening centrally inside the capsulorhexis and the outer capsule. Four of our cases of sunset syndrome had no demonstrable capsular material for support,and apparently the IOLs had been placed on the hyaloid face. These lenses dislocated immediately after implantation. The can-opener technique can lead to situations in which the anterior capsule may not be visible behind a mid-dilated pupil, and its edges may be difficult to see even if the iris is retracted. These four cases might have been avoided if a clearly demarcated capsulorhexis had been performed and the surgeon had been aware that capsule was no longer present. Mansour and 478
coauthors 5 reported placement of an IOL in the ciliary sulcus on the hyaloid face in one case in which there was still posterior capsule present anterior to the IOL; it is not clear whether the hap tics were entangled in the peripheral capsular material or the iris. Flynn and coauthors6 reported that dislocated IOLs in the vitreous cavity can, after extended periods, cause secondary complications such as retinal detachment and cystoid macular edema. We agree that these lenses should be removed. Furthermore, many times these individuals cannot see clearly (1) if the lens bisects the pupillary area or (2) if they are left aphakic and are unable to wear contact lenses. We would be reluctant to place a new IOL in an eye with a dislocated lens left in place. There have been other reports on exchanging or repositioning posterior chamber IOLs.6-12 We agree with Nabors and coauthors 7 that a pars plana vitrectomy is essential when suture fixating a posterior chamber lens, either to the ciliary sulcus area or the iris. In our experience this technique minimized later difficulties with vitreous traction around the IOL, or vitreous prolapse through the pupil, and potential difficulties related to the wound in which manipulation of the implant may have occurred through a limbal incision. In cases in which we fixate lenses to the iris with sutures we use a uniplanar lens. Previously placed lenses with angulated haptics can cause the peripheral haptic to push up against the peripheral iris when the lens is sutured to the iris. We have recently begun to fixate lenses to the sclera with sutures, and in those situations we prefer to have a lens that is specifically designed for that placement. We believe choosing the correct lens for implantation helps minimize difficulties with further dislocation or decentration. As these individuals have already had difficulty with a poorly fixated lens, we want to minimize the possibility of recurrence. One major question in repositioning posterior chamber lenses is whether the IOL can be placed on the remaining capsular material. One can be led into thinking there is sufficient capsular support present only to have the IOL dislocate, either during surgery or months later. While there is still no perfect technique for determining the extent of capsular support, we have found the use of a prototype endoscopic camera, manufactured by Alcon Surgical, to facilitate direct visualization of the zonular and capsular area. Without this camera, it is essentially impossible in the surgical setting to examine the peripheral area around the ciliary body.
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER
1992
Of the 15 lenses removed for anisometropia, eight were because of difficulties encountered after penetrating keratoplasty. Although advances in predicting the final keratometric results of corneal transplants have been made, this is still an area in which surprises are common to surgeons performing transplants. Occasionally, situations requiring that lenses be removed will develop. For patients who are not having a penetrating keratoplasty, new advances in axial length measurements may help minimize the occurrence of significant anisometropia. Laser damage should be avoidable by proper aiming, correct power setting on the laser, or by aborting the procedure in uncooperative patients. Dealing with the complications of endophthalmitis and chronic inflammation is more difficult. In four of the 18 cases with chronic inflammation the posterior chamber lens was partially or completely captured by the pupil, resulting in significant irritation and inflammation from iris contact with the haptics and sometimes the edges of the IOL optic. The continuous tear capsulotomy may minimize the occurrence of pupillary capture in which the pupil was originally anterior to the optic but gradually retracted posterior to the optic. In other cases it was difficult to diagnose the actual cause of the chronic inflammation. In some we suspected chronic endophthalmitis but were unable to culture an organism or to identify one in the removed pathologic specimens. In some cases, infection may have been present and been appropriately treated, only to have antigens or some other inflammatory material continue the chronic inflammation. Eyes with chronic endophthalmitis or chronic inflammation are very difficult to treat. The mean time from implantation to removal for chronic endophthalmitis was 17.5 months and for chronic inflammation, 34 months. The mean time from implantation to the occurrence of symptoms was 13 months for endophthalmitis and 20 months for inflammation. The occurrence of endophthalmitis after cataract surgery is so rare that it is difficult to devise specific guidelines to decrease its incidence. A higher incidence could occur with cataract surgery, considering the proximity of the eyelashes and external surface of the eye to the surgical procedure. Based on our experience, lens diameters should be greater than 12.0 mm to ensure good sulcus
fixation (Table 2). Three eyes had haptic diameters of 12.0 mm and two 12.5 mm, yet a windshieldwiper syndrome resulted. In two other cases, there were larger than normal corneal diameters, and even the 13.5 mm haptic diameter was insufficient. In one of these later patients, a lens placed in the capsular bag was well fixated in the other eye. If sulcus-fixation is attempted the horizontal whiteto-white diameter and axial length should be checked. Unusually large measurements for either of these could cause standard posterior chamber lenses to have inadequate sulcus fixation. In-thebag fixation offers the most reliable means of posterior chamber lens fixation. REFERENCES 1. Stark WJ, Sommer A, Smith RE. Changing trends in intraocular lens implantation (editorial). Arch Ophthalmol1989; 107:1441-1444 2. Tetz MR, Apple DJ, Price FW Jr, et al. A newly described complication of neodymium-YAG laser posterior capsulotomy: exacerbation of an intraocular infection. Arch Ophthalmol1987; 105:1324-1325 3. Solomon KD, Apple DJ, Mamalis N, et al. Complications of intraocular lenses with special reference to an analysis of 2500 explanted intraocular lenses (IOLs). Eur J Implant Refract Surg 1991; 3:195-200 4. Hansen SO, Tetz MR, Solomon KD, et al. Decentration of flexible loop posterior chamber intraocular lenses in a series of 222 postmortem eyes. Ophthalmology 1988; 95:344-349 5. Mansour A, Blodi CF, Yannis RA, Kimura AE. Intraocular lens placement behind the posterior capsule. Ophthalmic Surg 1990; 21:211-212 6. Flynn HW Jr, Buus D, Culbertson WW. Management of subluxated and posteriorly dislocated intraocular lenses using pars plana vitrectomy instrumentation. J Cataract Refract Surg 1990; 16:51-56 7. Nabors G, Varley MP, Charles S. Ciliary sulcus suturing of a posterior chamber intraocular lens. Ophthalmic Surg 1990; 21:263-265 8. Maguire AM, Blumenkranz MS, Ward TG, Winkelman JZ. Scleral loop fixation for posteriorly dislocated intraocular lenses; operative technique and long-term results. Arch Ophthalmol1991; 109:1754-1758 9. Stark WJ, Goodman G, Goodman D, Gottsch J. Posterior chamber intraocular lens implantation in the absence of posterior capsular support. Ophthalmic Surg 1988; 19:240-243 10. Smiddy WE. Dislocated posterior chamber intraocular lens: a new technique of management. Arch Ophthalmol 1989; 107:1678-1680 11. Doren GS, Stern GA, Driebe WT. Indications for and results of intraocular lens explantation. J Cataract Refract Surg 1992; 18:79-85 12. Eifrig DE. Two principles for repositioning intraocular lenses. Ophthalmic Surg 1986; 17:486-489
J CATARACT REFRACT SURG-VOL 18, SEPTEMBER 1992
479
![[Implantation of folding posterior chamber lenses].](/assets/img/hold.png)
