Abstract
Abstract: :
Purpose:Secondary cataract formation due to proliferation and migration of remaining lens epithelial cells in the capsular bag occurs in 28.4% of all patients undergoing cataract surgery after 5 years. Low dose irradiation with P-32-labeled PMMA rings implanted into the capsular bag of NZW rabbits was found to be effective in the inhibition of PCO. The aim of this study was to evaluate the effect of single fraction irradiation on secondary cataract formation prior to cataract surgery in vitro. Methods: Pig eyes were available from the local slaughterhouse. The lenses were isolated from the bulbi and 4 lenses each were irradiated with 8, 10, 12 or 20 Gy. Radiation was applied by a linear accelerator (Siemens Mevatron, 6 MeV beam). 2 hours after irradiation the lenses were fixed with histoacryl glue in custom made lens holders of medical steel (lens holder model by El-Osta, ARVO 2000). A central capsulorrhexis was performed and the nucleus was removed by irrigation and aspiration. The lens capsular bags were incubated at physiological conditions in petri dishes containing DMEM supplemented with 10% FCS. Incubated specimens were examined daily with a microscope and lens epithelial cell proliferation was observed until capsular confluence was reached. Parameters assessed were time taken until first sign of lens epithelial cell proliferation on the posterior capsule and time taken to complete coverage of the posterior capsule. Results were compared with a control group of 4 unirradiated lenses. Results: Ionizing irradiation showed a significant decrease in time taken to complete coverage of the posterior capsule with lens epithelial cells. Average time until the complete coverage of the posterior capsule increased from 6.5 days for the untreated controls to 12.5 days for the 8 Gy irradiated lenses, 17 days for the 10 Gy irradiated lenses and 24.5 days for the 12 Gy irradiated lenses. Only 1 out of 4 20 Gy irradiated lenses showed epithelial cell proliferation. Capsular confluence was reached after 34 days. Conclusion:Single fraction irradiation appears to inhibit epithelial cell proliferation and migration and therefore the formation of secondary PCO in vitro.
Keywords: 522 posterior capsular opacification (PCO) • 538 radiation therapy • 338 cataract