Changes to the Anterior Capsular Opening of Human Lens after Cataract Surgery in Patients with Subluxated Lenses. Summary of the Doctoral Thesis

Abstract

Surgery of subluxated lenses represents one of most challenging types of surgeries in anterior parts of the eye; it is characterised by prolonged surgery time, individual surgery tactics with a high risk of involuntary change of tactics due to complicated course of surgery, as well as an increased rate of intraoperative and postoperative complications, and potentially less favourable postoperative outcomes if compared to standard cataract surgery. Phacoemulsification as standard surgery type for cataracts with lens subluxation should be used to minimise potential complications of surgery, along with utilising capsular stabilisation devices. Analysis of anterior capsule contraction after cataract surgery of subluxated lens reveals short-term and long-term efficacy of the method in these cases. Aim. To analyse changes of the anterior capsule opening (capsulorrhexis) after cataract surgery of subluxated lenses and to prove the connection to weak/ absent zonules, as well as efficacy of surgical method used for the type of disease. Methods. The present research included a sample of 53 patients (53 eyes) with different types of lens subluxation, capsulorrhexis contraction after phacoemulsification surgery and capsular tension ring (CTR) or modified CTR (mCTR or Cionni) implantation, who were analysed during the first six months following the above treatments. The rate of late IOL-CTR-capsular bag dislocations as long term (5 years after the last patient was recruited) outcomes were analysed. Results. Mean capsulorrhexis area reduction achieved was from 14.25 mm2 to 12.13 mm2 from the first postoperative day to a result six months later and it represents a 14.8 % reduction, with this result demonstrating statistical significance (p < 0,001). Reduction rates in cases of trauma history mean the reduction was 15.57 mm2 to 12.72 mm2, representing a 18.30 % reduction, while in cases without a history of trauma – capsulorrhexis reduction rate achieved was 13.66 mm2 to 11.87 mm2, representing 13.10 % reduction. If a CTR 11 mm was implanted, capsulorrhexis area reduction achieved was from 13.70 mm2 to 10.58 mm2 (reduction by 22.7 %). If a CTR 12 mm was implanted, capsulorrhexis opening reduction achieved was from 14.61 mm2 to 13.43 mm mm2 (reduction by 8.07 %). If CTR was implanted, capsulorrhexis reduction was from 13.90 mm2 to 11.30 mm2 (18.70 %), if mCTR (Cionni) was implanted – from 14.65 mm2 to 13.33 mm2 (9.01 %). Reduction of capsulorrhexis size during the first 3 months after surgery can be predicted by means of linear regression. Predictors are the following: implicated eye, diameter of CTR, glaucoma, trauma. All predictors demonstrate statistical significance on capsulorrhexis reduction during the first 3 months after surgery (p < 0.05). For the present doctoral thesis a second type of regression model was designed for real capsulorrhexis reduction during first 3 months after surgery. The model includes: capsulorrhexis size on the 1st day after surgery, implicated eye, diameter of CTR, glaucoma. All predictors have statistically significant (p < 0.05) influence on capsulorrhexis size during the first 3 months after surgery. Seven patients suffered late IOL-CTR-capsular bag dislocation, observed during the research period between 2011 and March 2020. Conclusions.The reduction of the anterior capsular opening after cataract surgery for patients with a subluxated lens is gradual, with the most rapid reduction 1 month post-surgery. A prediction model has been developed for the capsulorrhexis area 3 month post-surgery value which allows for the more accurate identification of patients with a greater risk of rapid reduction in the capsulorrhexis. Postoperative and late complications are observed more for patients with pseudoexfoliation syndrome and glaucoma. Late IOL-CTR-capsular bag dislocation in the subluxated lens group can often be encountered, but its development period in the long-term post-operation period does not differ from the time for late IOL dislocation patients after non-complicated cataract surgery. Zonular weakness/absence, a small initial capsulorrhexis and the non-polishing of the anterior capsule’s LEC does not influence the size of the contraction of the anterior capsule, if a CTR or a modified CTR and a hydrophobic acrylic IOL are used in the surgery. The use of a capsular tension ring or a modified capsular tension ring reduces the contraction of the anterior capsule opening significantly over time, with the size of the contraction being comparable to the case of a non-complicated cataract surgery. Zonular weakness/absence, a small initial capsulorrhexis and the non-polishing of the anterior capsule’s LEC does not influence the size of the contraction of the anterior capsule, if a CTR or a modified CTR and a hydrophobic acrylic IOL are used in the surgery. Subluxated lens cataract surgery can be compared to standard cataract surgery, using additional instruments and devices (iris and capsular hooks, a CTR or mCTR) for lens and capsular bag stabilisation, zonular conservation and stabilisation, so as not to deepen the defect. Recommendations have been developed for surgical tactics in the treatment of subluxated lenses to reduce postoperative and late complication risks.