Visual acuity and color discrimination in patients with cataracts.

Color vision tests can give information about pathological changes in eye structures. The purpose of our research was to study the color vision sensitivity and visual acuity changes before and after cataract surgery. We used a saturated Farnsworth D15 color vision arrangement test to check color sensitivity changes in confusion line directions. The test is easily perceptible (essential to eldery patients), and it is possible to check color sensitivity changes in tritan, protan, and deutan confusion line directions. The results were analyzed in several ways: by summing the color differences between adjacent caps according to Bowman and averaging the color difference vectors according to Vingrys and King-Smith. Color difference vectors determine the severity (or confusion), selectivity (or scatter), and type of color deficiency to the presented cap arrangements. In the least squares regression method, the error type is determined by the angular proximity of the best-fit line to known confusion axes representing protan, deutan, tritan, or unspecified color defects. All three tests showed that cataract-induced lens opacity significantly decreases a patient's chromatic resolution in the visible light region. Before the cataract surgery, the D15 test stimulus arrangement sequence showed similarities with tritan color deficiency.