Quantitative phenotyping of chromatic dysfunction in best macular dystrophy.
OBJECTIVE
To quantify chromatic dysfunction in Best disease to reassess the classic categorization of macular chromatic damage and to investigate psychophysical and clinical correlations.


METHODS
Color-contrast discrimination was measured using 2 different psychophysical strategies in age-matched control (n = 41) and patient (n = 34) eyes. The first strategy measured performance along 3 main confusion lines (testing cone function), and the second evaluated discrimination ellipses (modified Cambridge Color Test). The main outcome measures were chromatic discrimination variables (confusion line length, ellipse length, angle, and axis ratio) and visual acuity (VA).


RESULTS
Significant loss of performance was seen in all color axes in our patients, and it increased monotonically with staging, becoming significant in Fishman stages 2 and 3. The classically assumed preferential type I red-green deficit was true only for stage 4. Substantial chromatic dysfunction occurred even with relatively preserved VA despite that negative correlations between all test variables and VA reached statistical significance. Partial correlation analysis showed that protan/deutan loss was related to VA independent of tritan loss. Statistically significant positive correlations were also found between lesion size and chromatic dysfunction.


CONCLUSIONS
Chromatic discrimination is often impaired in Best disease, even when VA is still spared. Our quantitative psychophysical approach shows that the classic categorization as a type I red-green deficit is valid only for disease stage 4.
Campos
Sónia H
SH
Center for Ophthalmology, Institute of Biomedical Research in Light and Image, Faculty of Medicine, University of Coimbra, Az. de Sta Comba, Celas 3000-354, Coimbra, Portugal.
Forjaz
Vasco
V
Kozak
Lajos R
LR
Silva
Eduardo
E
Castelo-Branco
Miguel
M
D000328:Adult; D003119:Color Perception Tests / Q000379:methods; D003117:Color Vision Defects / Q000175:diagnosis* / Q000503:physiopathology; D015350:Contrast Sensitivity; D006801:Humans; D008268:Macular Degeneration / Q000175:diagnosis* / Q000503:physiopathology; D010641:Phenotype; D011603:Psychophysiology / Q000379:methods; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology; D014792:Visual Acuity