Abstract
Purpose: :
Access retinal function in patients with mitochondrial diseases.
Methods: :
A total of 34 patients with presumed mitochondrial disease (ragged red fibers on muscle biopsy, biochemical enzyme complex deficiencies and/or a specific genetic defect) were submitted to an ophthalmic evaluation including assessment of visual symptoms and visual acuity, dilated indirect ophthalmoscopy, retinal photography, and retinal electrophysiology.
Results: :
Thirty-two (94%) of the patients had abnormal full-field ERG, including delay in cone b-wave implicit time (68,43%), reduced maximum response a-wave amplitude (61,76%), maximum response b-wave implicit time delay (54,41%), 30Hz flicker implicit time delay (54,41%), reduced maximal response b-wave amplitude (50%), reduced cone b-wave amplitude (45.58%), reduced 30Hz flicker amplitude (44,11%), scotopic b-wave implicit time delay (35,29%), reduced scotopic b-wave amplitude (32,35%) and maximum response b-wave implicit time delay (22,06%).
Conclusions: :
Abnormalities of retinal function are common in subjects with mitochondrial disorders. Fullfield ERG abnormalities precedes fundoscopic changes and visual symptoms in mitochondrial disorders. The delay in cone b- wave implicit time may reflect abnormal cone-rod interactions; cone-reduced sensitivity in their response to light; or initial macular involvement, at it was confirmed by multifocal ERG in some patients.
Keywords: mitochondria • electroretinography: clinical • photoreceptors