Development and validation of a novel and graded colour saturation threshold test, the LSS-8

Colour vision changes are a key clinical feature of many acquired retinal and optic nerve disorders. Current clinical tests are often labour-intensive or designed for congenital defects. We introduce the novel LSS-8 test, which measures colour saturation thresholds across eight hues. Three cohorts with mixed ocular health underwent testing in a diagnostic crossover study. The reliability cohort was tested with LSS-4 on different days (n = 30 eyes). The screen independence cohort used LSS-8 with 11-inch versus 13-inch screens in random order (n = 27 eyes). Brightness independence testing used LSS-8 at 115 cd/m² versus 230 cd/m² (n = 19 eyes). Scores for each plate set and total scores were recorded. Intraclass correlation coefficients (ICC) and difference frequency distributions were calculated. Data from 74 eyes (74 subjects; mean age 62.4 ± 19.1 years; range 20-85; 39% female) were analysed, with two participants contributing to two study phases. LSS-4 test-retest reliability with ICC(2,1) was good to excellent (mauve 0.93, red 0.95, green 0.87, blue 0.91, total score 0.96). LSS-8 screen independence testing showed excellent reliability for mauve, green, pink and total scores, and moderate to good reliability for other hues (ICC(2,k) 0.74-0.98). Varying screen brightness did not produce significant score differences in most participants. The LSS is a simple, reliable test with potential for rapid quantification of acquired colour vision defects.