Purpose: Very poor visual acuity often cannot be measured with letter charts even at close viewing distances. The Berkeley Rudimentary Vision Test (BRVT) was developed as a simple test to extend the range of visual acuity measurement beyond the limits of letter charts by systematically simplifying the visual task and using close viewing distances to achieve large angular sizes. The test has three pairs of hinged cards, 25 cm square. One card-pair has four single tumbling E (STE) optotypes at sizes 100 M, 63 M, 40 M, and 25 M. Another card-pair has four grating acuity (GA) targets at sizes 200 M, 125 M, 80 M, and 50 M. The third card-pair has a test of white field projection (WFP) and a test of black white discrimination (BWD). As a demonstration of feasibility, a population of subjects with severe visual impairment was tested with the BRVT.
Methods: Adults with severe visual impairments from a wide variety of causes were recruited from three different rehabilitation programs. Vision measurements were made on 54 eyes from 37 subjects; test administration times were measured.
Results: For this population, letter chart visual acuity could be measured on 24 eyes. Measurements of visual acuity for STE targets were made for 18 eyes and with GA targets, for two eyes. Five eyes had WFP, and one had BWD. Four had light perception only. The median testing time with the BRVT was 2.5 min.
Discussion: The BRVT extends the range of visual acuity up to logMAR = 2.60 (20/8000) for STEs, to logMAR = 2.90 (20/16,000) for gratings and includes the WFP and BWD tests.
Conclusions: The BRVT is a simple and efficient test of spatial vision that, with 13 increments, extends the range of measurement from the limits of the letter chart up to light perception.