Chromatic and luminance contrast sensitivities in asymptomatic carriers from a large Brazilian pedigree of 11778 Leber hereditary optic neuropathy.
OBJECTIVE
To determine whether asymptomatic 11778 LHON carriers demonstrated impairments in (1) chromatic red/green (R/G) and blue/yellow (B/Y) contrast sensitivity functions (CSF) and in (2) luminance contrast sensitivity functions in the spatial CSF (SCSF) and temporal CSF (TCSF) domains.


METHODS
Twenty-five carriers (8 male, 17 female; 34.1 +/- 15.1 years of age) of homoplasmic 11778 LHON from the same well-described family and 30 age-matched controls (17 male, 13 female; 29.2 +/- 7.1 years of age) were tested in one eye, randomly selected. Of the 25 eyes tested, 18 had normal fundus, 5 had swelling and microangiopathy, and 2 had temporal pallor. The R/G and B/Y CSFs were obtained after equiluminance correction with bichromatic horizontal sinusoidal gratings at 0.3, 0.7, and 2 cycles per degree (cpd); the SCSFs were obtained with achromatic gratings at 0.3, 2, 6, and 12 cpd; and the TCSFs were obtained at 2, 10, 20, and 33 Hz with sinusoidal modulation of a 2.7 degrees field with a superimposed spatial Gabor function.


RESULTS
Differences between carriers and controls were statistically significant for all spatial frequencies of chromatic and luminance SCSFs, but not for the TCSFs. R/G equiluminance settings of carriers differed from those of controls (P < 0.001), requiring higher luminance in the green; B/Y equiluminance settings were not statistically different in carriers and controls. Fundus findings did not correlate with CS results.


CONCLUSIONS
Luminance and chromatic spatial CS losses that affected all tested spatial frequencies, are reported in LHON asymptomatic carriers with the mtDNA 11778 mutation. No losses were found in the temporal CSF. An intriguing finding is that the blue system is substantially spared in this LHON family. These represent subclinical visual impairments in otherwise asymptomatic LHON carriers.
Ventura
Dora Fix
DF
Department of Experimental Psychology, University of São Paulo, São Paulo, Brazil. dventura@usp.br
Quiros
Peter
P
Carelli
Valerio
V
Salomão
Solange R
SR
Gualtieri
Mirella
M
Oliveira
André G F
AG
Costa
Marcelo F
MF
Berezovsky
Adriana
A
Sadun
Federico
F
de Negri
Anna Maria
AM
Sadun
Alfredo A
AA
D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D005425:Flicker Fusion; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D029242:Optic Atrophy, Hereditary, Leber / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology*; D010375:Pedigree; D013028:Space Perception; D014792:Visual Acuity
D004272:DNA, Mitochondrial