Purchase this article with an account.
Laryssa Huryn, Irini Manoli, Elizabeth Harrington, Jennifer Sloan, Brian Patrick Brooks, Charles Venditti, Wadih M Zein; Optic Nerve Atrophy in Methylmalonic Acidemia (MMA). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5554.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To investigate the topographic pattern of retinal nerve fiber layer thickness (RNFL) of patients with isolated MMA caused by methylmalonyl-CoA mutase deficiency using spectral domain optical coherence tomography (SD-OCT).
Twenty- three patients with isolated MMA (15 mut, 5 cblB and 3 cblA deficiency) admitted through a dedicated natural history protocol at the National Institutes of Health (NCT00078078) underwent comprehensive ophthalmic evaluations. Visual acuity, color vision and Cirrus optical coherence tomography (Carl Zeiss Meditec, Inc) data was analyzed. For patients under 18 years of age, normative data published in the literature was used. Two patients were removed from the analysis because of lack of adequate OCT scans due to age and reduced cooperation.
Age at presentation for ophthalmic examination ranged from 10 to 31 years (20.1y +/- 6.9y). Visual acuity at baseline examination ranged from 20/12.5 to 20/800. Seventeen patients presented with at least 20/25 visual acuity in one eye; of these, seven had demonstrable RNFL thinning. Of the eighteen patients that had documented color vision examinations at presentation, only two had abnormal results; one of these patients presented with 20/25 visual acuity. Two patients developed significant vision loss and optic atrophy with thinning of the superior and inferior portions of the optic nerve. Of the patients with optic nerve atrophy and no vision loss, the superior and inferior quadrants of the optic nerve were most often involved.
Optic nerve atrophy is a well-known feature of mitochondrial disease. Many mechanisms for the pathogenesis of mitochondrial optic neuropathy have been proposed including bioenergetic failure, oxidative stress and glutamate toxicity. The atrophy in MMA patients presents primarily in the superior and inferior quadrants of the optic nerve as measured by OCT which differs from other optic neuropathies. It is recommended that patients undergo regular eye examinations, including OCT to monitor for changes in retinal nerve fibers. Future studies with OCT measurements may help shed light on changes that occur over time as well as highlight the earliest signs of change and a potential therapeutic window in this disease process.
This PDF is available to Subscribers Only