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Young Jung Roh, Young Gun Park; Electroretinographic findings associated with selective retina therapy (SRT) versus conventional panretinal photocoagulation (PRP) in rabbits. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6353.
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Subvisible selective retina therapy (SRT) was intended to target the retinal pigment epithelium (RPE) without thermal damage to the adjacent photoreceptors. We evaluated changes in electroretinographic (ERG) findings after SRT compared to panretinal photocoagulation (PRP) in rabbits.
One eye of twelve chinchilla rabbits was treated with 150 spots of either SRT or conventional laser treatment. Right eyes of six rabbits received SRT(527nm, 20-25uJ, 200um) (SRT group; n = 6) and right eyes of the other six rabbits were treated with PRP( 577nm,150mW,200um) (PRP group; n = 6). Fluorescein angiography was performed to demonstrate SRT lesions(Figure1). The operated eyes were investigated with full-field ERG according to ISCEV standards at 1hr and at 3 weeks after treatment. The eyes were enucleated at 3 weeks after that, and hematoxylin and eosin staining was employed to monitor the extent and depth of the laser effects.
At 1 day after treatment, ROD b-wave amplitude was reduced to 64 ± 4 % of baseline in the PRP group compared to baseline and 93 ± 6 % in the SRT group. This reduction was significantly larger in the PRP group than in the SRT group (P <0.05 ; t Test). Similar results were observed for the dark-adapted Combined Response (CR) b-wave amplitude, the reduction in CR b-wave amplitude was significantly larger in the PRP group than in the SRT group. CR a-wave, oscillatory potentials, cone single flash, and 30 Hz flicker responses showed no statistically differences in between-group analyses. At 3 weeks later, the differences were reduced due to recovery in both PRP and SRT groups. Especially b-wave amplitude in SRT group made no difference compared to baseline at 3 weeks. Histology showed selective RPE damage sparing photoreceptor continuity.
SRT in the rabbit eyes induces less functional loss than PRP group in both rod- and cone-mediated retinal function in full-field ERG. Especially SRT group showed no difference compared to baseline. These results suggest that SRT achieves selective targeting of the RPE without the inner and outer retinal damage.
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