The SKILL card test in optic neuritis: Experience of the optic neuritis treatment trial

Objectives To assess the value of the Smith-Kettlewell Institute Low Luminance (SKILL) Card test, designed to measure vision at reduced contrast and luminance, among patients with previous optic neuritis. Materials and Methods The SKILL Card test was administered to 295 patients participating in the Optic Neuritis Treatment Trial (ONTT) follow-up study, concurrent with measurement of visual acuity, visual field, contrast sensitivity, and color vision. Health-related quality of life (HRQL) was also assessed in a subset of patients using the National Eye Institute Visual Function Questionnaire and an ONTT-developed questionnaire. Results The SKILL Card difference score (high-contrast acuity score minus low-contrast acuity score) was only weakly associated with the other measures of vision function (r_s absolute range, 0.05-0.31) and with the HRQL measures (r_s absolute range, 0.02-0.15). In contrast, the light and dark component scores of the SKILL Card test had higher associations with the other vision measures (r_s absolute range, 0.27-0.54) and with the HRQL measures (r_s absolute range, 0.10-0.40). Conclusions The SKILL Card difference score is not a meaningful measure for patients with optic neuritis; however, the test appears to have clinical usefulness as a method to measure high-contrast and low-contrast acuity.