Abstract
Abstract: :
Purpose: to evaluate color vision and luminance contrast sensitivity in Duchenne Muscle Dystrophy (DMD). Methods: DMD patients belonged to the following groups: G1: no gene deletions (n=20); G2: deletions upstream exon 30 (n=7); G3: deletion downstream exon 30 (n=27). Controls: 35 age–matched subjects. Color vision was evaluated with: Cambridge Colour Test (CCT) (CRS Ltd), Neitz Anomaloscope, Ishihara and AO H–R–R plates. Luminance contrast sensitivities (CS) were measured with PSYCHO for Windows (CRS Ltd). For spatial CS (SCS) the frequencies were: 0.5, 1, 2, 5, 10 and 20cpd. For temporal CS (TCS) the frequencies were: 1, 2, 10, 20 and 33Hz. Results: Color vision losses measured by the CCT were found in 34/54 (63%) patients, the majority of which (27/34, 79%) had a red–green defect, confirmed by the anomaloscope results (Wilcoxon test – Trivector p= .602; Ellipse p< .999). The AO H–R–R and Ishihara plates were less sensitive, revealing respectively, 24% and 16% of red–green color vision losses; and these results did not correlate with the Rayleigh matches (AO H–R–R p= .016; Ishihara p< .001). The SCS were reduced at all frequencies (p< .05) for DMD groups 1 and 3. All frequencies were reduced in TCS (p< .05) except for 33Hz for DMD group 1 and 3. Patients of group 3 with red–green color defect showed a statistical worse results: 1 (p< .007), 2 (p= .019), 10 (p= .010), 20 (p= .009) Hz. Conclusions: Red–green and contrast sensitivity losses occur in DMD patients. The most affected are patients with deletion downstream exon 30, whose impairment is in the Dp260, the retinal dystrophin isoform, suggesting a possible linkage between the DMD and L – M cone genes. A red–green color defect in DMD patients without gene deletion could be indicating a possible point mutation downstream exon 30.
Keywords: color vision • contrast sensitivity • genetics