Mitochondrial diseases frequently manifest neuro-ophthalmologic symptoms and signs. Because of the predilection of mitochondrial disorders to involve the optic nerves, extraocular muscles, retina, and even the retrochiasmal visual pathways, the ophthalmologist is often the first physician to be consulted. Disorders caused by mitochondrial dysfunction can result from abnormalities in either the mitochondrial DNA or in nuclear genes which encode mitochondrial proteins. Inheritance of these mutations will follow patterns specific to their somatic or mitochondrial genetics. Genotype-phenotype correlations are inconstant, and considerable overlap may occur among these syndromes. The diagnostic approach to the patient with suspected mitochondrial disease entails a detailed personal and family history, careful ophthalmic, neurologic, and systemic examination, directed investigations, and attention to potentially life-threatening sequelae. Although curative treatments for mitochondrial disorders are currently lacking, exciting research advances are being made, particularly in the area of gene therapy. Leber hereditary optic neuropathy, with its window of opportunity for timely intervention and its accessibility to directed therapy, offers a unique model to study future therapeutic interventions. Most patients and their relatives benefit from informed genetic counseling.

The ODDS Consortium recommendations are important in the process of establishing a reliable and consistent diagnosis of ODD using OCT for both clinicians and researchers.

for the ODDS ConsortiumBackground: With the development and widespread adoption of spectral-domain optical coherence tomography (OCT), peripapillary hyper-reflective ovoid mass-like structures (PHOMS) have become a frequent OCT finding in neuro-ophthalmic practice. Although originally assumed to represent a form of buried optic disc drusen (ODD), PHOMS differ from ODD in many important ways. The histopathological underpinnings of PHOMS are now becoming more clearly understood. Evidence acquisition: Review of literature. Results: PHOMS can be broadly classified as disk edemaassociated PHOMS, ODD-associated PHOMS, or anomalous disk-associated PHOMS. PHOMS are seen in many conditions, including papilledema, nonarteritic anterior ischemic optic neuropathy, central retinal vein occlusion, acute demyelinating optic neuritis, ODD, and tilted disks (myopic obliquely inserted disks) and in many cases resolve along with the underlying condition. The histopathological study of these diverse entities reveals the common feature of a bulge of optic nerve fibers herniating centrifugally over Bruch membrane opening into the peripapillary space, correlating exactly with the location, shape, and space-occupying nature of PHOMS on OCT. Because of the radial symmetry of these herniating optic nerve fibers, PHOMS are best thought of as a complete or partial torus (i.e., donut) in 3 dimensions. Conclusions: PHOMS are a common but nonspecific OCT marker of axoplasmic stasis in the optic nerve head. They are not themselves ODD or ODD precursors, although they can be seen in association with ODD and a wide spectrum of other conditions. They do not exclude papilledema and often accompany it. The circumferential extent and characteristic 3D toroidal nature of a PHOMS are best appreciated by scrolling through consecutive OCT images.

IMPORTANCE Intravenous (IV) administration of corticosteroids is the standard of care in the treatment of acute optic neuritis. However, it is uncertain whether a bioequivalent dose of corticosteroid administered orally, which may be more cost-efficient and convenient for patients, is as effective as IV administration in the treatment of acute optic neuritis. OBJECTIVE To determine whether recovery of vision following treatment of acute optic neuritis with a high-dose IV corticosteroid is superior to that with a bioequivalent dose of an oral corticosteroid. DESIGN, SETTING, AND PARTICIPANTS This single-blind (participants unblinded) randomized clinical trial with 6-month follow-up was conducted at a single tertiary care center in London, Ontario, Canada. Participants were enrolled from March 2012 to May 2015, with the last participant's final visit occurring November 2015. Patients 18 to 64 years of age presenting within 14 days of acute optic neuritis onset, without any recovery at time of randomization and without history of optic neuritis in the same eye, were screened. Inclusion criteria included best-corrected visual acuity (BCVA) of 20/40 or worse and corticosteroids deemed required by treating physician. In total, 89 participants were screened; 64 were eligible, but 9 declined to participate. Thus, 55 participants were enrolled and randomized. Primary analysis was unadjusted and according to the intention-to-treat principle. INTERVENTIONS Participants were randomized 1:1 to the IV methylprednisolone sodium succinate (1000-mg) or oral prednisone (1250-mg) group. MAIN OUTCOMES AND MEASURES Primary outcome was recovery of the latency of the P100 component of the visual evoked potential at 6 months. Secondary outcomes were the P100 latency at 1 month and BCVA as assessed with Early Treatment Diabetic Retinopathy Study letter scores on the alphabet chart and scores on low-contrast letters at 1 and 6 months. RESULTS Of 55 randomized participants, the final analyzed cohort comprised 23 participants in the IV and 22 in the oral treatment groups. The mean (SD) age of the cohort was 34.6 (9.5) years, and there were 28 women (62.2%). At 6 months' recovery, P100 latency in the IV group improved by 62.9 milliseconds (from a mean [SD] of 181.9 [53.6] to 119.0 [16.5] milliseconds), and the oral group improved by 66.7 milliseconds (from a mean [SD] of 200.5 [67.2] to 133.8 [31.5] milliseconds), with no significant difference between groups (P = .07). Similarly, no significant group difference was found in the mean P100 latency recovery at 1 month. For BCVA, recovery between the groups did not reach statistical significance at 1 month or 6 months. In addition, improvements in low-contrast (1.25% and 2.5%) BCVA were not significantly different between treatment groups at 1 or 6 months' recovery. CONCLUSIONS AND RELEVANCE This study finds that bioequivalent doses of oral corticosteroids may be used as an alternative to IV corticosteroids to treat acute optic neuritis. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT0152...