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Chi D Luu, Josephine Gunawan, Emily Caruso, Robyn H Guymer; Effect of subthreshold nanosecond laser treatment on rod photoreceptor function. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2998.
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© ARVO (1962-2015); The Authors (2016-present)
Abnormal rod function in intermediate age-related macular degeneration (iAMD), particularly in eyes with reticular pseudodrusen (RPD), has been thought to be associated with a declined in the function of the retinal pigment epithelium (RPE) and Bruch’s membrane (BM). Recently, it has been shown in preclinical studies that RPE and BM’s functional impairment can be reversed by subthreshold nanosecond laser (SNL) treatment. The purpose of this study was to determine whether SNL treatment improves rod function in subjects with iAMD.
Eligible subjects with bilateral iAMD were treated with SNL, where 100 spots were delivered at baseline, to the superior and inferior arcades of the study eye. Dark-adapted perimetric examination was performed at baseline (prior to SNL treatment), and at 2 weeks, 3, 6, 12 months after SNL treatment. At each visit, the retina was bleached ~20% and retinal sensitivities for 505 and 625 nm stimuli were obtained at multiple retinal locations. Retinal sensitivities for the 505nm stimulus were repeatedly measured in a dark room for 30 minutes. Retinal sensitivity for the 625nm stimulus was obtained once after the 505nm stimulus testing completed. Rod function was determined by 3 parameters; the sensitivity differences (ΔS) between the 505 and 625 nm stimuli, the rod intercept time (RIT) and rod recovery rate (RRR).
Twenty-one subjects with iAMD (4 also had RPD) were recruited. All participants had BCVA of 20/40 or better. In general, subjects with RPD had worse rod function than subjects without RPD. In iAMD subjects without RPD, there were no significant changes detected in any of the rod functional parameters following SNL treatment (p > 0.14). In iAMD subjects with RPD, there was an improvement in rod function, with a peak improvement observed at 8° inferior retina at 3 months post treatment (with a median ΔS = 22 dB, RIT =15.6 minutes and RRR = 0.10 log units/minute) compared to baseline values (ΔS = 15 dB, RIT = 30 minutes and RRR = 0.05 log units/minute). At 12 months post SNL treatment, all functional parameters returned to the baseline level.
There appeared to be a temporary improvement in rod function in iAMD cases with RPD at 3 months post SNL treatment, however, improvement in rod function was undetectable in cases without RPD. These findings warrant further investigation on the mechanisms of action and dosing of the SNL treatment.
This is a 2020 ARVO Annual Meeting abstract.
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