Chromatic and luminance contrast sensitivities of carriers of 11778 Leber‘s Hereditary Optic Neuropathy (LHON) from a giant pedigree in Brazil

Purpose: To determine (1) luminance contrast sensitivity functions (CSF) in the spatial (SCSF) and temporal domains (TCSF) and (2) chromatic red/green (R/G) and blue/yellow (B/Y) CSFs in 11778 LHON carriers with no visual complaints. Methods: The subjects, carriers (n= 27) and age–matched controls (n = 30), were tested monocularly in a darkened room. CSFs were measured with PSYCHO for Windows v 2.36 (Cambridge Research Systems), with a VSG 2/4 graphic board and a Sony FD Trinitron monitor, calibrated with a CS1000 Minolta spectrophotometer. The SCSF was measured with horizontal sinusoidal gratings at 0.3, 2, 6 and 12 cpd; the TCSF at 2, 10, 20 and 33 Hz using sinusoidal modulation of a 30 degree field with a superimposed spatial Gabor function. R/G and B/Y CSFs were determined with horizontal sinusoidal gratings of 0.3, 0.7 and 2 cpd, after equiluminance correction. The u'v' (CIE 1976) chromaticity coordinates were: D6500: 0.198, 0.468; Red: 0.258, 0.454; Green: 0.133, 0.469; Blue: 0.210, 0.397 and Yellow: 0.188, 0.551. A non–parametric statistical analysis (Mann–Whitney Rank Sum test with alpha= 0.05) was performed. Results:Differences between the carriers and controls were statistically significant for all spatial frequencies of both chromatic and luminance spatial contrast modulation tests, but not for the temporal CSFs. R/G equiluminance settings of carriers differed from controls (p