Ophthalmic features of Friedreich ataxia

To describe ocular abnormalities in patients with Friedreich ataxia (FRDA).

Patients diagnosed with FRDA by genetic analysis were invited to participate in a prospective cohort. The patients included underwent an extensive ophthalmologic examination, including low-contrast Sloan letter charts test and retinal nerve fiber layer (RNFL) thickness analysis by optical coherence tomography (OCT).

Twenty-three patients agreed to participate. In all, 19 patients (83%) had a visual acuity of at least 0.8 in both eyes. Fundus examination showed diffuse optic nerve pallor in four patients. However, OCT showed a decreased mean peripapillary RNFL thickness in all but three adult cases and one teenager. The RNFL thickness was found to have a positive correlation with visual acuity (P=0.001) and contrast sensitivity (P=0.001) and a negative correlation with time elapsed from diagnosis (P=0.001).

OCT and low contrast test sensitivity show that the visual pathway is affected in FRDA. However, in most patients there is no significant visual impairment. In a small proportion of patients visual acuity declines with disease progression. This study provides a better understanding of the ophthalmic features of FRDA.