Performance of a Rapid Rarebit Central-Vision Test with Optic Neuropathies

Purpose Rarebit vision tests probe for gaps in the neuro-retinal receptive field matrix, using bright micro dots on a dark background. Previous reports have found central-vision rarebit tests useful for macular lesions. Their performance with lesions of the anterior visual pathways has not been explored. Methods Twenty-two subjects with optic nerve lesions of light to moderate severities were examined with a novel, self-contained rarebit test. Outcomes were contrasted with results of high-pass resolution perimetry and a threshold letter acuity test. Results The results of the three tests differed significantly from those of normal control subjects. There were no meaningful inter-test correlations. Analysis of receiver-operating characteristic curves revealed closely similar powers of discrimination. Mean test time for the rarebit test was 1:42 min, and for the other tests, it was approximately 5 min each. Conclusions The rarebit test appeared highly capable of detecting optic neuropathies and chiasmal lesions. Its simplicity and short test duration indicate a useful role in screening settings.