Abstract
Purpose::
Mitochondrial encephalomyopathies constitute a relatively common group of neurometabolic diseases in childhood. They are caused by defects in the oxidative phosphorylation due to mutations in either the nuclear or the mitochondrial DNA (mtDNA). Since 1988, more than 100 mutations of mtDNA have been reported, including large-scale rearrangements, as well as point mutations. Different ophthalmologic findings, such as external ophthalmoplegia, optic disc atrophy and retinal degeneration have previously been reported. The purpose of this study was to describe ophthalmologic findings in patients with mitochondrial diseases with known genotypes.
Methods::
A retrospective study was performed in 52 patients (26 males; 26 females) born between 1967-2002, having genetically verified mitochondrial encephalomyopathies. 51 of these subjects had undergone a detailed ophthalmologic examination including visual acuity (VA), eye motility, refraction, slit-lamp examination, ophthalmoscopy and in several cases also electroretinogram (ERG) and pachymetry.
Results::
43/51 (84%) of the patients had one or more ophthalmologic findings such as ptosis (n=16), reduced eye motility (n=14), severe external ophthalmoplegia (n=5), strabismus (n=6), nystagmus (n=4), low VA (n=19), refractive errors (n=14), increased corneal thickness (n=10), photophobia (n=3), optic atrophy (n=15), pigmentation in the macula and/or periphery (n=11), and ERG-verified retinal dystrophy (n=7). Some genotypes (i.e. mtDNA deletion) have a more severe ophthalmologic phenotype than others
Conclusions::
The results show that a majority of patients with mitochondrial encephalomyopathies has ophthalmologic abnormalities. We recommend that an ophthalmologic examination, including ERG, should be performed in all children and adolescents who are suspected to have a mitochondrial disease.
Keywords: mitochondria • clinical (human) or epidemiologic studies: prevalence/incidence • optic nerve