Ophthalmic Surgery, Lasers and Imaging Retina

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CLINICAL SCIENCE 

Neodymium:YAG Laser Anterior Capsulotomy for Capsular Contraction Syndrome

Sumil P Deokule, FRCSEd(Ophth); Subhanjan S Mukherjee, FRCSEd; Chris K S Chew, FRCOphth

Abstract

* BACKGROUND AND OBJECTIVE: This study presents the outcome of neodymium:YAG laser anterior capsulotomy for capsular contraction syndrome, the safety profile and effectiveness of which are unclear.

* PATIENTS AND METHODS: Records of 32 patients with a minimum of 3 months of follow-up were reviewed retrospectively. The procedure was considered successful if all of the following criteria were met: centered intraocular lens (IOL) or no obvious change in IOL centration post-capsulotomy; no evidence of re-phimosis in the follow-up period; and no further requirement for surgical intervention due to capsular contraction syndrome in the follow-up period or complications were recorded.

* RESULTS: The procedure was successful in 25 cases (78%). Failed cases (n = 7, 22.0%) included 5 cases of re-phimosis and 2 cases with progressive IOL decentration. The failure rate was higher in cases with preoperative IOL decentration (P < .01).

* CONCLUSION: Neodymium:YAG laser anterior capsulotomy was successful in the majority of cases. The failure rate was higher with preoperative IOL decentration.

[Ophthalmic Surg Lasers Imaging 2006;37:99105.]

Abstract

* BACKGROUND AND OBJECTIVE: This study presents the outcome of neodymium:YAG laser anterior capsulotomy for capsular contraction syndrome, the safety profile and effectiveness of which are unclear.

* PATIENTS AND METHODS: Records of 32 patients with a minimum of 3 months of follow-up were reviewed retrospectively. The procedure was considered successful if all of the following criteria were met: centered intraocular lens (IOL) or no obvious change in IOL centration post-capsulotomy; no evidence of re-phimosis in the follow-up period; and no further requirement for surgical intervention due to capsular contraction syndrome in the follow-up period or complications were recorded.

* RESULTS: The procedure was successful in 25 cases (78%). Failed cases (n = 7, 22.0%) included 5 cases of re-phimosis and 2 cases with progressive IOL decentration. The failure rate was higher in cases with preoperative IOL decentration (P < .01).

* CONCLUSION: Neodymium:YAG laser anterior capsulotomy was successful in the majority of cases. The failure rate was higher with preoperative IOL decentration.

[Ophthalmic Surg Lasers Imaging 2006;37:99105.]

INTRODUCTION

The anterior capsulotomy aperture and the equatorial diameter of the capsular bag decrease over a period of 3 to 6 months following phacoemulsification surgery. 1_6 This response may be exaggerated, leading to capsular contraction syndrome, the condition first described by Davison.7 Capsular contraction syndrome was initially identified in eyes with Pseudoexfoliation, uveitis, high myopia, and pars planitis, with zonular weakness being purported as a common factor.2,8,9 Subsequently, it has been reported in eyes with retinitis pigmentosa and diabetic retinopathy.1012 Other factors that may influence capsule contraction are size of continuous curvilinear capsulorhexis, the intraocular lens (IOL) design, IOL biomaterial, and lens epithelial cell metaplasia.5,10,13"15 The contraction is reported to be more pronounced with silicone biomaterial and platehaptic lens design.1,2,5,13"18

Capsular contraction syndrome may result in visual impairment and refractive change.7"9,12,18'20 Partial coverage of the visual axis due to phimosis and eccentric displacement of the continuous curvilinear capsulorhexis opening can lead to reduced visual acuity, reduced contrast sensitivity, and increased glare. Other complications such as ocular hypotony secondary to the ciliary body detachment, IOL decentration, and IOL tilt have been associated with capsular contraction syndrome.7"9,14,21"23 Furthermore, in patients with diabetic retinopathy and high myopia, the presence of an opaque anterior capsule impedes a thorough retinal examination.

Neodymium:YAG (Nd:YAG) laser anterior capsulotomy has been employed successfully to treat capsular contraction syndrome.3,4,7"9,12,18"25 The aim of capsulotomy is to release the capsular contraction and to maintain the IOL centration. The complication rate following this procedure is low, although early and late IOL dislocation has been reported.21,26 Nonetheless, further examination is required to determine the effectiveness, long-term safety, and full complication profile of this procedure, particularly in eyes implanted with a three-piece silicone IOL. To the best of our knowledge, the largest series reporting the outcome of Nd:YAG anterior capsulotomy included only 14 patients.12 We report the outcome of Nd:YAG laser anterior capsulotomy for capsular contraction syndrome in a series of 32 patients.

PATIENTS AND METHODS

This retrospective study includes 32 cases of Nd:YAG laser anterior capsulotomy from January 2001 to December 2002 at Wolverhampton & Midland Counties Eye Infirmary. All cases had a minimum follow-up of 3 months and had previously undergone phacoemulsification with in-the-bag placement of a three-piece foldable silicone IOL implant by various surgeons (Allergan SI-30NB lenses [Irvine, CA] were used in 30 cases and Bausch and Lomb Soflex lenses [Rochester, NY] were used in 2 cases). Anterior capsular phimosis was diagnosed in the presence of contraction of the anterior capsular aperture within the undilated pupillary aperture, along with any of the following findings: anterior capsule aperture decentration, IOL decentration with or without reduced visual acuity, or visual disturbance and difficulty in examining the fundus.

The following data were collected from the case record review: gender, age, interval between the phacoemulsification surgery and the capsulotomy, and complications. A history of preoperative pseudoexfoliation, uveitis, ocular trauma, and diabetes was noted. In addition, the following data were collected from preoperative and postoperative visits: best-corrected visual acuity, intraocular pressure (IOP), and IOL centration.

The capsulotomy was classified as successful if it met all of the following criteria: centered IOL or no obvious change in IOL centration post-capsulotomy; no evidence of re-phimosis in the follow-up period; and no further requirement for surgical intervention due to capsular contraction syndrome during the follow-up period. Cases with re-phimosis, progressive IOL decentration, or those that had to undergo further surgery for capsular contraction syndrome were classified as a failure.

Nd:YAG laser capsulotomy was performed with the HGM Nd:YAG laser machine (Heston, Middlesex, UK). The capsulotomy was performed for anterior capsular phimosis in all cases except one. In one case, anterior capsular phimosis was associated with pupillary membrane formation. The linear technique of laser capsulotomy was employed and an attempt was made to cut the circular fibrotic band in each case. A single cut was generally used for each quadrant, but the quadrant where the anterior capsular edge was in close proximity to the pupil was avoided. More than one cut was employed in other quadrants in such cases. The length of the cut required was judged on the basis of the width of the fibrotic band, attempting to cut the full vertical extent of the fibrotic band. AU cases were given topical steroids for 1 week postoperatively.

The data were collected on an Excel 2000 work sheet (Microsoft Inc., Redmond, WA) and analyzed using Minitab statistical software (Minitab Inc., State College, PA). The success rates of cases in which capsulotomy was performed within 6 months of the original cataract surgery and 6 or more months after the original surgery were compared using Fisher's exact test. The success rates of cases with preoperative centered IOL and preoperative IOL decentration were compared using the Mann-Whitney U test. Categoric variables were compared with the chi-square test. P values of less than .05 were considered statistically significant.

Table

TABLE 1Demographic and Selected Clinical Characteristics of Eyes Undergoing Anterior Capsulotomy for Capsular Contraction Syndrome

TABLE 1

Demographic and Selected Clinical Characteristics of Eyes Undergoing Anterior Capsulotomy for Capsular Contraction Syndrome

RESULTS

The average age of the patients was 72.1 ± 13.3 years (range, 43 to 92 years). There were 18 men and 14 women. Four cases in our series had non-insulindependent diabetes mellitus and background diabetic retinopathy, 4 cases had high myopia, 1 case had Pseudoexfoliation, and 1 case had recurrent uveitis. Two cases had excessive postoperative anterior chamber inflammation and 1 case had iris prolapse in the early postoperative period that was corrected surgically.

The average interval between the phacoemulsification surgery and capsulotomy was 14.0 ± 2.5 months (range, 3 to 24 months). The mean follow-up was 10.3 ± 7.3 months. Twenty-five capsulotomies (78.0%) resulted in a successful outcome and 7 capsulotomies (22.0%) resulted in failure. The success rate was greater for capsulotomy performed within 6 months of the original surgery than for capsulotomy performed 6 or more months after the original surgery; however, the difference did not reach statistical significance (P = .06). Similarly, the success rate was significantly greater in cases with a preoperative centered IOL compared to cases with a preoperative decentered IOL (P < .01).

There was no statistically significant difference between the successful cases and failed cases regarding gender, age, and number of shots. These results are summarized in Table 1 .

Table

TABLE 2Complications Reported Following Anterior Capsulotomy

TABLE 2

Complications Reported Following Anterior Capsulotomy

Table

TABLE 3Pattern of Intraocular Lens Decentration and Outcome of the Anterior Capsulotomy

TABLE 3

Pattern of Intraocular Lens Decentration and Outcome of the Anterior Capsulotomy

Failed cases included 5 cases of re-phimosis and 2 cases of progressive IOL decentration postoperatively.

Of the 5 cases of re-phimosis, 3 underwent surgical capsulotomy with IOL replacement and 2 chose the conservative management. The complications observed in this study are presented in Table 2. IOL decentration was noted in 10 cases preoperatively, of which 5 cases resulted in failure (3 phimosis and 2 further decentration). The pattern of decentration is presented in Table 3. Posterior capsulotomy was performed simultaneously in 3 cases and at a later date in 2 cases.

Figure. Scatterplot presenting preoperative and postoperative Snellen visual acuity (VA). Visual acuity is presented as the number of Snellen chart lines read preoperatively and postoperatively.

Figure. Scatterplot presenting preoperative and postoperative Snellen visual acuity (VA). Visual acuity is presented as the number of Snellen chart lines read preoperatively and postoperatively.

The best-corrected Snellen visual acuity either remained the same or improved in 29 cases postoperatively (Figure). The visual acuity improved by 1.3 ± 2.0 Snellen lines (range, -3 to 7 lines) in the overall case series and 1.5 ± 1.5 Snellen lines (range, 0 to 7 lines) after successful capsulotomy. None of the cases with failed capsulotomy demonstrated any improvement in visual acuity. Elevated IOP was not reported in any cases.

DISCUSSION

Capsular contraction syndrome results due to the excessive fibrosis of the edge of the anterior capsular and reduction of the equatorial diameter of the capsular bag. Weak zonules and asymmetric capsular bag contraction can lead to IOL decentration. The intensity of fibrosis is maximum in the early postoperative period, but the process may continue for several months.1"6 Davison was the first to advocate the use of NdrYAG laser anterior capsulotomy to interrupt the contraction forces without the need for further surgical intervention and to prevent IOL decentration.7 Subsequently, several investigators have successfully used this modality to enlarge the anterior capsular aperture.3,4,7"9,12,18"24 A successful anterior capsulotomy should be able to enlarge the anterior capsular aperture, maintain an enlarged aperture and IOL centration, reverse symptoms of glare and visual reduction, and provide a clear view of the fundus for retinal examination without necessitating further surgical intervention.

An ideal definition of the successful outcome should include all of the above criteria. However, due to the retrospective nature of the study, we were able to include only the IOL centration, re-phimosis, and need for further surgical intervention or lack of it in our definition of the successful outcome. Applying this definition, 78% of capsulotomies were classified as successful in our study. All of the successful cases either improved on or maintained the preoperative Snellen visual acuity. On the other hand, none of the failed cases demonstrated improvement in Snellen visual acuity. This result supports the definition of successful anterior capsulotomy adopted in our case series.

The process of anterior capsule opacification is thought to progress in four stages: (1) opacification of capsulorhexis margin; (2) opacification of the entire anterior capsule in contact with the IOL optic; (3) formation of capsular folds; and (4) eccentric displacement of the continuous curvilinear capsulorhexis and IOL decentration due to excessive and asymmetric shrinkage.15 In our study, 10 cases had preoperative IOL decentration, suggesting advanced stages of anterior capsular opacification. This may be why 5 of those 10 cases resulted in failure.

Seven cases that were classified as a failure demonstrated continued contraction of the anterior capsular aperture. Five of those 7 cases developed re-phimosis, including 1 case that suffered complete phimosis and 2 cases that demonstrated progressive IOL decentration (Table 4). No preexisting conditions apart from preoperative IOL decentration were observed in 2 cases with progressive IOL decentration. Some cases of late dislocation of the plate-haptic IOL following anterior capsulotomy have been reported,21,26 although to our knowledge, no case of late dislocation involving a three-piece IOL has been reported so far. Both cases in our series are being closely monitored, but neither had required IOL replacement by their last visit.

Two of the 5 cases that developed re-phimosis had a time delay of greater than 12 months, whereas preoperative IOL decentration was present in 3 cases, thus supporting the presence of advanced stages of anterior capsular fibrosis.

The IOL material and design are significant factors in the development of capsular contraction syndrome. Several studies have confirmed the higher incidence of anterior capsular contraction with silicone biomaterial compared with polymethylmethacrylate and acrylic biomaterial.1"3,5 One comparative autopsy tissue study with clinicopathologic correlation demonstrated significant clinical sequelae in the three-piece silicone optic-polypropylene haptic design, with 7 of 10 cases of capsulorhexis phimosis observed in the study being associated with the above type of IOL, which also presented with the highest decentration.15 Some reports suggest that polymethylmethacrylate haptics maintain the capsulorhexis diameter more effectively than polypropylene haptics.2,27 However, in one comparative study, the polypropylene haptic and the polymethylmethacrylate haptic did not differ significantly in preventing capsular contraction syndrome.3 All lenses in our study were of silicone biomaterial and 30 of 32 IOLs were of the silicone optic-polypropylene haptic variety. This factor surely would have contributed to a high occurrence of capsular contraction syndrome and subsequent failure of laser anterior capsulotomy in arresting capsular contraction syndrome in our study. The use of SI-30NB lenses has since been stopped in favor of lenses with other biomaterial and design.

Table

TABLE 4Details of Failed Cases

TABLE 4

Details of Failed Cases

The interplay between retained lens epithelial cells, capsulorhexis size, and IOL optic position in relation to capsulorhexis may be associated with capsular contraction syndrome. The clinical impression is that larger central continuous curvilinear capsulorhexis and anterior capsule polishing reduces the likelihood of capsular contraction syndrome. Whether the surgical technique of original phacoemulsification and laser anterior capsulotomy could have predisposed to development of capsular contraction syndrome and the subsequent failure of anterior capsulotomy cannot be ascertained in this study because data were collected retrospectively. The recording of specifics of the surgical technique of the cataract surgery such as capsulorhexis size or anterior capsule vacuuming was not uniform and therefore was not included in this study. Furthermore, inadequate laser treatment may also predispose to rephimosis. The opening up of the space between the two sides of a radial tear should be noticeable at the time of capsulotomy with a linear cut extending throughout the full extent of the fibrotic band. Re-phimosis has been reported only once before in the literature because anterior capsulotomy failed to treat capsular contraction syndrome and to relieve the choroidal detachment necessitating a surgical capsulotomy.23

Hayashi et al. reported using anterior capsulotomy in 14 of 47 eyes with retinitis pigmentosa within 12 months of the cataract extraction.12 No serious complications were reported except occasional extension of the radial tear to the equator. The authors did not specify the number of eyes with tear extension, but none of the eyes developed IOL decentration. The same authors also described using anterior capsulotomy in 5 eyes with Pseudoexfoliation, although the outcomes were not reported.8 Hurvitz reported 9 cases of capsular contraction syndrome in combined trabeculectomy and cataract surgery that were successfully treated with laser anterior capsulotomy.21 Apart from minimal hyphema and visually non-consequential IOL pitting, no complications were encountered in this series.

Similarly, Dahlhauser et al. successfully employed anterior capsulotomy for capsular contraction syndrome in 10 eyes with Pseudoexfoliation implanted with a plate-haptic silicone IOL.22 The mean best-corrected visual acuity improved from 20/50 before anterior capsulotomy to 20/25 postoperatively. IOL decentration was observed in 3 cases that did not progress after the capsulotomy. However, the follow-up period and the symptomatology is not specified. Furthermore, one IOL dislocated posteriorly, presumably due to simultaneous rupture of the anterior capsule and the posterior capsule at the optic edge, requiring an IOL exchange. Tuft and Talks reported 2 cases of plate-haptic silicone lens dislocation 1 month after capsulotomy, secondary to a peripheral extension of the radial tear.26

Other complications reported in our study include hyphema, which cleared within 1 week, in 1 case with pupillary membrane and posterior synechiae and 1 case with asymptomatic anterior surface lens pitting. Although none of our patients demonstrated significant inflammatory signs in the anterior chamber after capsulotomy, uveitis remains a distinct possibility. Similarly, use of the Nd: YAG laser on the anterior capsule can lead to endothelial cell loss due to the shock waves, which may be crucial in the cornea with compromised endothelial function. None of the patients in our series have demonstrated corneal decompensation so far, the longest follow-up being 1 8 months. Late focal corneal decompensation has been reported due to the remnant of the anterior capsule, but a circular technique was employed in this case.28 No capsular fragments are released with the radial tear technique.

The timing for the capsulotomy remains a point of discussion. In our series, a time delay of 6 or more months was selected as a cut-off point for early and late intervention. This distinction was made because capsular contraction syndrome usually is a slowly progressing condition and most clinicians tend to wait for 6 months or more before performing anterior capsulotomy. The success rate was higher in eyes that underwent capsulotomy within 6 months compared to eyes undergoing capsulotomy with a delay of greater than 6 months, although the difference was statistically not significant. Five failed cases had a time delay of greater than 6 months and only one failed eye underwent capsulotomy within 6 months of the original surgery.

Although our study demonstrates the benefit of performing the procedure within 6 months, the role of very early capsulotomy (ie, within 3 months of the original cataract surgery) is not clear. Several studies have shown that the capsular contraction is greatest in the first 6 weeks, but can continue up to 6 months or beyond at a slower pace in some cases.1"6 Therefore, it is reasonable to assume that interrupting the pathologic process of contraction at an early stage may prevent a more severe outcome of this condition. Although 5 of 6 cases with capsulotomy performed within 3 months of the original surgery in our series were successful, the number is too small to reach any conclusion. Further randomized trials are necessary to explore the efficacy and safety of very early intervention.

Our study demonstrates the need to use anterior capsulotomy with caution in cases with capsular contraction syndrome. It is successful in the majority of cases, but complications are encountered in a significant minority and particularly in cases with preoperative IOL decentration. The appropriate timing of the intervention needs to be explored further, and our current recommendation is to base this decision on individual case merits.

REFERENCES

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2. Zambarakji H, Rauz S, Reynolds A, Joshi N, Simcock PR, Kinnear PE. Capsulorhexis phimosis following uncomplicated phacoemulsification surgery. Eye. 1997;11:635-638.

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11. Hayashi H, Hayashi K, Nakao F, Hayashi F. Area reduction in the anterior capsule opening in eyes of diabetes mellitus patients. / Cataract Refract Surg. 1998;24:1105-1110.

12. Hayashi K, Hayashi H, Matsuo K, Nakao F, Hayashi F Anterior capsule contraction and intraocular lens dislocation after implant surgery in eyes with retinitis pigmentosa. Ophthalmobgy. 1998;105:1239-1243.

13. Joo CK, Shin JA, Kim JH. Capsular opening contraction after continuous curvilinear capsulorhexis and intraocular lens implantation. / Cataract Refract Surg. 1996;22:585-590.

14. Hayashi K, Hayashi H, Nakao F, Hayashi F Anterior capsule contraction and intraocular lens decentration and tilt after hydrogel lens implantation. BrJ Ophthalmol. 2001;85:1294-1297.

15. Werner L, Pandey S, Apple D, Escobar-Gomez M, McLendon L, Macky TA. Anterior capsule opacification: correlation of pathologic findings with clinical sequelae. Ophthalmobgy. 200 1 ; 1 08: 1 675- 1681.

16. Cochener B, Jacq P, Colin J. Capsule contraction after continuous curvilinear capsulorhexis: poly(methyl methacrylate) versus silicone intraocular lenses. / Cataract Refract Surg. 1999;25:1362-1369.

17. Gonvers M, Sickenberg M, van Melle G. Change in capsulorhexis size after implantation of three types of intraocular lenses. / Cataract Refract Surg. 1997;23:231-238.

18. Reeves P, Yung C. Silicone intraocular lens encapsulation by shrinkage of the capsulorhexis opening. / Cataract Refract Surg. 1 998;24: 1 275- 1 276.

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TABLE 1

Demographic and Selected Clinical Characteristics of Eyes Undergoing Anterior Capsulotomy for Capsular Contraction Syndrome

TABLE 2

Complications Reported Following Anterior Capsulotomy

TABLE 3

Pattern of Intraocular Lens Decentration and Outcome of the Anterior Capsulotomy

TABLE 4

Details of Failed Cases

10.3928/1542-8877-20060301-04

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