Comparison of the Apoptotic and Histopathologic Change in Transpupillary Thermotherapy and Short Pulse Laser Photocoagulation in Rabbit

Abstract

Abstract: : Purpose: To compare apoptotic and histopathologic changes in the retina and choroid of laser burns that were made with transpupillary thermothery (TTT) and converntional short pulse photocoagulation (PC) and showed silimar changes ophthalmoscopically. Methods: TTT and PC were performed in rabbit eyes with diode laser(SLx, Iris medical, 810nm). The end point was barely detectable light-gray appearance in both groups. In the TTT group, the laser was applied at a lower power for 60 seconds. In the PC group, the laser with 0.1 second of duration and higher power was used. The eyes were severed at 3, 6, 12, 24, 48, and 72 hours after laser treatment, and the specimens were processed with TdT-dUTP terminal nick-end labeling (TUNEL) staining to detect apoptotic cells, H&E;, and toluidine blue staing. The TUNEL positive cells were counted, and the proportion of the stained cells in each retinal and choroidal layer was calculated. Results: In the TTT group, TUNEL positive cells were found much less in the neurosensory retina than in the choroid compared to the PC group in which relatively larger number of apoptotic cells were also found in the retina. In the micoroscopic examination, changes in the outer retina and retinal pigment epithelium were more prominant in the PC group than in the TTT group. Conclusions: Distribution of apoptotic cells was different depending on the laser method. TTT can be used in the treatment of choroidal disease, such as choroidal neovacularlization and choroidal melanoma with avoiding neural retinal layer damage.

Keywords: microscopy: confocal/tunneling • laser • choroid: neovascularization