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SC Lin, M-J Chen, RL Stamper; Ciliary Body Vascular Changes of Cyclophotocoagulation in a Rabbit Model . Invest. Ophthalmol. Vis. Sci. 2002;43(13):311.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the acute and chronic hemodynamic effects of endoscopic cyclophotocoagulation (ECP) versus transscleral cyclophotocoagulation (TCP) in a rabbit model. Method: The endoscopic laser (EndoOptiks, Little Silver, NJ)was fitted with appropriate color filters at the camera and light source ports to perform endoscopic fluorescein angiography (FA). FA was recorded in real time on digital video. Three rabbits were used as controls for endoscopic FA of the ciliary body. Nine rabbits underwent ECP in one eye and another nine rabbits had unilateral TCP. Intraocular FA was performed immediately, one day and one month after surgery. The eyes were evaluated in regards to their ciliary body vascular perfusion. Three rabbits in each group had endoscopic ciliary body FA at each time point. The masked observer described the vascular integrity of the ciliary processes which included three to four processes within a photographic frame. Results: Normal functional ciliary processes were fluorescent within 5 seconds of fluorescein injection and became hyperfluorescence with observation. Ablated processes were hypofluorescent. Immediately after laser, both TCP and ECP eyes demonstrated severely reduced or nonexistent ciliary body blood flow. The ciliary tissues of TCP eyes exhibited areas of central hypofluorescence with surrounding zones of hyperfluorescence which was indicative of less uniform treatment. ECP eyes showed dense hypofluorescence of ciliary processes, corresponding to the previous treatment sites. At one day, both TCP and ECP eyes showed similar findings as that of the immediate treatment. At one month, TCP eyes demonstrated markedly irregular patterns of mixed hypo- and hyperfluorescence. This scattered fluorescence likely represented residual viable ciliary processes with partially perfused blood flow. ECP eyes showed uniform early fluorescence with less leakage (hyperfluorescence) in the late phase, compared to untreated areas within the same eye and untreated eyes. Slightly less early fluorescence was observed when compared to the untreated processes. Therefore, at least partially reperfused ciliary blood flow was noted in the ECP rabbits at 1 month post-treatment. Conclusion: Uniform reperfusion of the ciliary body blood flow in the ECP-treated rabbits may indicate partial preservation of vascular perfusion to an important ocular tissue. In contrast, TCP-treated eyes showed many areas of marked hypoperfusion at the 30-day time point. This may account for the very low rates of phthisis and hypotony observed with ECP in the clinical situation.
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