The effect of a 550 nm cutoff filter on the vision of cataract patients.

The effect on visual function of an optical filter which absorbs essentially all visible wavelengths below 550 nm has been studied in a group of patients with moderate stage cataracts. Using a Snellen-type visual acuity chart with a blue background and orange letters, under both glare and non-glare conditions, the visual acuity of these patients was determined. Improvement in acuity was more striking under glare conditions than under standard (non-glare) conditions; in the former case it reached levels as high as 300% in a few patients. The level of the improvement seemed to be related both to cataract type and stage of cataract progression.