Restitution of potential visual acuity in low vision patients with the use of yoke prisms

PURPOSE: To determine the efficacy of prisms when used for redirection of incoming images towards the preferred reinal loci (PRLs) for restitution of potential visual acuity (PVA) in low vision cases with age-related macular degeneration (AMD). METHODS: Retrospective comparative interventional case series review. Low vision rehabilitation (LVR) protocol used included best corrected visual acuity (BCVA), PVA, topographic PRL identification and use of prisms to produce image redirection to the presumed PRL. The primary outcome measure selected for analysis was BCVA for viewing distance targets after use of yoke prisms. RESULTS: Image relocation with prisms in patients with AMD resulted in significantly better BCVA levels (t(32) = 8.57, p < 0.0001) in the better eye. Distance BCVA levels achieved were almost identical to PVA levels (t(32) = 0.415, p < 0.681) (y= -0.136 + 1.195x, r = 0.8333, p < 0.001). CONCLUSIONS: Use of yoke prisms for image redirection towards a peripheral identifiable PRL may result in PVA restitution in most cases.