Searching the way out for posterior capsule opacification.

Searching the way out for posterior capsule opacification was one of our goals in improving current cataract surgery techniques. The second goals was restoring accommodation but this goal prooved to remain unsolved. The bag-in-the-lens concept of IOL and implantation technique has been used in 271 patients of which 15 children. These patients have a follow-up of one month to 5 years. The optical axis of all these patients remained crystal clear, which allows us to conclude that the problem of PCO is solved by the bag-in-the-lens implantation concept. These very encouraging results inspired us to new ideas, which will receive priority in our research: accommodation and optimising the quality of vision by compensating for the ocular aberrations.

The effect of photodynamic therapy with bacteriochlorin a on lens epithelial cells in a capsular bag model.

Photodynamic therapy (PDT) with bacteriochlorin a(BCA) has proved to be a successful treatment for many cancers and to be cytocidal for different cell lines in culture. The present study aimed to investigate in vitro the potential of this treatment for killing lens epithelial cells (LECs) left in the human capsular bag after extracapsular cataract extraction (ECCE). Capsular bags were prepared from donor eyes using an ECCE procedure and incubated in various concentrations of bacteriochlorin a(1.6-50 microg ml(-1)) during various incubation periods (2-10 min). Subsequently, the capsules were illuminated during various exposure times (2-15 min) with a diode laser (wavelength 760 nm). After treatment, the capsular bags were cultured for 7 days in Eagle's minimal essential medium supplemented with 2% fetal calf serum. The specimens were fixed in glutaraldehyde/paraformaldehyde and examined with routine light microscopy, Hoechst staining for DNA and transmission electron microscopy. Proliferation of LECs on the posterior capsule was assessed in flat mounts. Capsular bags receiving BCA without illumination and capsular bags receiving illumination only served as controls.BCA alone or light alone have no effect on structure and proliferative activity of LECs. At a threshold protocol of incubation in BCA at 10 microg ml(-1)for 10 min and subsequent illumination for 15 min, proliferative activity of cells is largely arrested and nearly all LECs on the capsule exhibit severe signs of apoptosis. Photodynamic therapy with bacteriochlorin a induces cell death and suppression of proliferation inlens epithelial cells and could be a promising means of prevention of posterior capsule opacification.

Quantitative measurement of the PCCC area in the postoperative period.

BACKGROUND/AIMS: The major complication of extracapsular cataract extraction (ECCE) is posterior capsule opacification (PCO). Posterior continuous circular capsulorhexis (PCCC) seems to be very promising in preventing PCO. This study was aimed at determining if the PCCC area changes as a function of time and if pearl formation could influence it. METHODS: 24 eyes of 23 patients underwent ECCE with PCCC. Retroillumination photographs were taken at 6 months and then yearly. To measure the PCCC area, the computerised program EPCO (evaluation of posterior capsule opacification) was used. The ratio of the PCCC area in relation to the IOL surface was calculated for the different time stages and the presence of pearl formation was noted. Firstly, proportional changes in diameter were compared in PCCC areas measured after 6 months and after 1 year (group I, n=13) and after 1 year and 2 years (group II, n=14). Secondly, PCCC areas were compared between two time stages in patients with (group III, n=19) and without pearl formation (group IV, n=8). RESULTS: No statistically significant difference was found in diameter change in either group. The PCCC area remains stabile between 6 months to 1 year and 1 year to 2 years. No differences are found between eyes with or without pearl formation. CONCLUSIONS: The PCCC area remains stable as a function of time and is not influenced by pearl formation.

Cell biological mechanisms underlying posterior capsule opacification: search for a therapy.

The present paper overviews our recent studies for PCO prevention using an in vitro human capsular bag model and application of hyperthermia and photodynamic therapy with Bacteriochlorin A as the sensitizer as described in previous papers. These studies clearly showed that both treatments are successful in vitro and almost completely reduce the proliferation of lens epithelial cells on the posterior capsule and thus are potential candidates to eliminate the occurrence of PCO in vivo. Hyperthermia has a threshold temperature between 55 degrees C and 60 degrees C which makes this approach not very useful for in vivo application. Threshold conditions for PDT/BCA are much more moderate. Recent preliminary in vivo studies in the rabbit showed that using the in vitro threshold conditions, the formation of a ring of Soemmering and outgrowth of lens epithelial cells on the posterior capsule is significantly reduced. However, these conditions have an adverse affect on the corneal stroma and endothelium. Studies of PDT conditions which further reduce LEC outgrowth without affecting the corneal integrity are in progress.

Secondary closure of posterior continuous curvilinear capsulorhexis in normal eyes and eyes at risk for postoperative inflammation.

PURPOSE: To observe the posterior continuous curvilinear capsulorhexis (PCCC) after cataract surgery in control eyes and eyes with an increased risk for postoperative inflammation. SETTING: Department of Ophthalmology, University Hospital Antwerp, Belgium. METHODS: After phacoemulsification, a PCCC was performed before intraocular lens (IOL) implantation in 20 eyes of 18 patients with ocular or systemic conditions that predisposed them for increased postoperative inflammation; e.g., diabetes, uveitis, retinitis pigmentosa (inflammation group). These eyes were compared with 20 eyes of 16 patients who had the same surgical procedure but did not present a history of medical or ocular pathology (control group). The postoperative follow-up was 6 months to 3 years. Reclosure of the PCCC was evaluated by anterior segment photographs. The reclosure was classified as partial when newly formed tissue was present at the PCCC margin and total when the proliferation covered the entire PCCC area. RESULTS: Three types of PCCC reclosure were found: fibrotic, Elschnig pearl or multilayer, and monolayer. All 3 were seen within or at the margin of the PCCC area. Reclosure (total and partial) occurred in 8 eyes (40%) in the control group and 10 (50%) in the inflammation group. Total reclosure was more frequent in the inflammation group (4 eyes [20%]) than in the control group (1 eye [5%]). Monolayered or multilayered cellular proliferation was present in 8 eyes (40%) in the control group and 4 eyes (20%) in the inflammation group; fibrotic proliferation was found in the inflammation group only (7 eyes [35%]). CONCLUSION: Reclosure of the PCCC occurred in both groups, although the frequency of reclosure was slightly higher in the inflammation group. Although PCCC does not prevent posterior capsule opacification in all cases, it is useful in specific situations.