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Chi D Luu, Rose Tan, Emily Caruso, Erica L Fletcher, Robyn H Guymer; Topographic rod functional recovery profiles after prolonged dark-adaptation in eyes with reticular pseudodrusen. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2411.
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Although rod function is known to be severely impaired in eyes with age-related macular degeneration (AMD) and reticular pseudodrusen (RPD), it remains unknown whether this impairment is associated with a total loss of rods or merely a delay in rod recovery. The purpose of the study was to determine rod functional recovery profiles following prolonged dark-adaptation (DA) in AMD eyes with RPD.
Recovery of rod function (retinal sensitivity) was assessed simultaneously at 14 retinal locations within the central 12° in the study eye of each subject after the eye received an approximately 20% bleach. Rod functional recovery was monitored at regular intervals up to 30 minutes after bleach. If retinal sensitivity of all test points did not recover to the rod criterion level (-3.0 log units of stimulus intensity) after 30 minutes of DA, monitoring the recovery of rod function was extended up to 24 hours of DA. Any test point with retinal sensitivity recovered beyond the rod criterion level, the rod function at that point was considered as has been recovered.
Six AMD cases with RPD (6 eyes) were included, age ranged 69-79 years, and best-corrected visual acuity of the study eye ranged from 20/20 to 20/25. All eyes had a delay in the recovery of rod function at many retinal locations. Although RPD were present at all test locations, the recovery rate was markedly different amongst retinal loci. Rod function within the central 6° recovered much slower compared to rod function outside the central 6°. Rod recovery was also different between subjects with different stages of RPD. In 5 cases with stage 2-3 RPD, rod function did recover at all the tested locations, but many locations took hours to do so. The case with stage 4 RPD, rod function did not recover even after 24 hours of dark-adaptation at several test points.
AMD eyes with RPD are associated with severe rod dysfunction throughout the macula, however, rod function does recover in most, but not all, cases after an extended dark-adaptation time. These findings suggest that the delay in rod recovery in eyes with RPD is, in most cases, associated with the impairment rather than total loss of function of rod photoreceptors. Stage 4 RPD may represent a point at which some rod photoreceptors are non-functional.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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