[Retinal ganglion cell layer and visual function in patients with progressive external ophthalmoplegia caused by...

Mitochondrial (mt) disorders are metabolic conditions with multiorgan involvement, which often cause neuroophtalmological symptoms. The aim of the study was to investigate the relation between progressive external ophthalmoplegia (PEO), visual pathway and mitochondrial DNA (mtDNA) mutations in patients younger than 55 years of age.

Five female patients (35 to 53 years of age) with mithochondrial disease were investigated. Automated threshold perimetry (Octopus G2 test), scanning laser polarimetry (GDx-VCC and GDx-ECC) and Fourier-domain optical coherence tomography (RTVue-100 OCT) were used in addition to detailed ophthalmological examination and evaluation of visually evoked potentials (VEP). Frequent mutations of the mtDNA were investigated in the patients' blood and muscle samples.

PEO of various severity levels was found in all patients, using clinical tests. Genetic testing showed "common deletion" of mtDNA in all cases. For both eyes of 4 patients functional and structural ophthalmic tests had normal results. In one patient decreased visual acuity, reduced retinal nerve fiber layer thickness and prolonged L3 VEP latency time were found without optic disc damage and visual field deterioration.

In 4 of our 5 patients with PEO due to common deletion of mtDNA retinal ganglion cells and visual function remained normal for a long period of life.