Instrument capable of grading eyes with severe visual loss: Estimation of visual function utilizing a novel device called the Low Vision Evaluator

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The purpose of this study is to develop an instrument capable of measuring and quantifying the visual capabilities of patients with severe yisual loss. The LoVE (Low Vision Evaluator) was made up of a pair of goggles with white, light-emitting diode as a stimulus, a control box, an on―off button to signal the detection of a stimulus, and a printer for permanent records. There were 15 levels of stimuli (combination of 5 intensitics and 3durations). The stimuli were delivered in a random sequence with an audio signal. Each eye was tested separately.The LoVE was capable of grading the visual function of retinitis pigmentosa (RP) patients with hand movement (HM) and light perception (LP) vision into finer steps. The Snellen visual acuity and visual field size (Steradian) were significantly correlated with LoVE score in RP patients. There were high correlations between the LoVE score and residual peripheral visual field in glaucoma eyes categorized as Vb Kozaki's classification. The LoVE thresholds of proliferative diabetic retinopathy (PDR) patients, whose fundi could not be observed due to vitreous hemorrhage and whose visual acuity was LP or HM, were determined. The LoVH thresholds of patients with a retinal detachment ware significantly lower than that of patients with no retinal detachment. The correlation between the LoVE thresholds and the amplitude of a- and b-waves of the ERG was significant. The LoVE is capable of grading the visual function of PDR patients with conventional LP and HM vision into finer steps, and it can be used to assess the visual function of patients with vitreous hemorrhage.The testing procedures were simple for the patients and examiner, and this instrument can be used to assess the effectiveness of medical and surgical therapy in patients with severe visual loss.