Abstract
Abstract: :
Purpose: Autosomal dominant cerebellar ataxias are a group of neurodegenerative hereditary disorders caused by triplet repeat mutations in various genes. The objective of the study was to describe ophthalmic findings in a group of patients in which the association of CAG repeat expansions in the coding regions of SCA 1, 2, 3, 6 and 7 genes had been firmly established. Methods: Fifteen patients whose DNA analysis revealed expanded allele of the trinucleotide repeats in the SCA 1,2,3,6 and 7 were examined. Ocular examination consisted of visual acuity, color vision (Farnsworth D 15), visual fields, intraocular pressure, stereo acuity, ocular motility, slit lamp examination, fundus exam and fluorescein angiography. Results: One patient was diagnosed with SCA1 (CAG repeat 51), 2 with SCA 2 (CAG repeat 40,44), 9 with SCA 3 (CAG repeats from 71-78), 2 with SCA 6 (CAG repeat 31,22) and 1 patient with SCA 7. Average age was 50, and 53% were male. Five patients (33%) had no visual complaints, 6 (40%) had diplopia, 2 blurred vision (13%), 1 patient (7%) with SCA 1 had nyctalopia, and the patient (7%) with SCA 7 presented with ophthalmoplegia and total blindness. Visual acuity was 20/20 in both eyes in 6 patients, 20/25-20/40 in 8 patients and NLP in one patient. Acquired color vision defect was seen in 8 (53%) of which 1 was SCA2, 6 SCA 3, and 1 SCA6. Stereo acuity was abnormal in 6 (40%), gaze evoked nystagmus was present in 9 (60%), ocular motility and saccades were abnormal in 9 (60%), pigmentary macular changes were seen in 2 (SCA1, SCA6) (13%) and optic atrophy in 1(7%, SCA 7). Conclusion: Although previously described only in SCA 7, acquired color vision defects were found in SCA 2, 3 and 6. This may indicate macular dysfunction due to presence of abnormal ataxins in the retina.
Keywords: 362 color vision • 554 retina • 562 retinal degenerations: hereditary