Visual function, ocular motility and ocular characteristics in patients with mitochondrial complex I deficiency

Purpose: The aims of the present study were to investigate visual function, ocular motility and ocular characteristics in children and young adults with complex I deficiency. Material and Methods: In a prospective study with longitudinal follow-up, the visual and ocular outcome in 13 patients with deficiency in complex I [nicotine-amide adenine dinucleotide (NADH) dehydrogenase] in the mitochondrial respiratory chain is presented. The patients were diagnosed during 1995-2007 and assessed during 1997-2009 at a median age of 12.8 years (range 3.1-23.4). Results: Twelve of 13 patients had visual impairment and/or ocular pathology. Four of 10 patients who co-operated in visual assessment had a best corrected decimal visual acuity of <= 0.5 in one or both eyes. Cataract surgery was performed in one patient and another patient showed retinal pigmentations and ptosis. Eleven patients demonstrated ocular motility problems, mainly saccade deficiencies. Five patients had optic atrophy (OA), which was bilateral in four patients. In four siblings, the OA showed a similarity to Leber's Hereditary Optic Neuropathy. These patients also had the 11778 G -> A mutation in mitochondrial DNA. Only one patient had normal visual acuity and ocular outcome including refraction and visual fields. Follow-up time was median 3.0 years (range 0-11). Conclusion: Visual impairment, ocular motility problems and OA are common in children and young adults with complex I deficiency and should prompt the paediatric ophthalmologist to consider mitochondrial disorders.