49 year old Man with Vision Loss

Case
49 year old gentleman presented with visual loss affecting his left eye three-four months ago which was sudden in onset without progression. This was followed by visual loss in the right eye later the same day. Approximately, one week later, he developed numbness to the bottom of the right foot and calf, which was followed by similar symptoms to the left leg approximately 2 weeks later. Patient denied any family history of visual loss. Patient followed up with Neurology outpatient and was prescribed 500-1000mg Prednisone daily for presumable Neuromyelitis optica, however NMO antibodies and prior MRI imaging have been negative. Patient , also visitied an opthomologist who diagnosed him with glaucoma of the left eye. As symptoms progressed, patient sought care in the nearest hospital for further evaluation and management.
In the ED, patient was hemodynamically stable, visual acuity depicted left eye 20/200 and right eye 20/70. Right visual fields intact, left eye with upper quadrant deficit. Normal opticokinetics. Impaired red distinction most prominent of the left. Left eye with increased optic disk margins, cupping size doubled on the left. CT head was unremarkable followed by repeat MRI orbits, brain and C-spine were all negative. Lumbar puncture was performed with cytology negative for oligoclonal bands, viral or bacterial etiology. Inpatient opthoalmology consult was gathered and demonstrated no evidence of optic neuritis however revealed evidence of glaucoma optic steroids. Patient was discharged and followed up with Neuro-opthalmology. On examination, corrected acuity was 20/200 O.U. COlor vision was 8/8 O.D. and 7/8 O.S. There was a suggestion of a small left afferent pupillary defect. There was a ceococentral scotoma in the right eye and a central scotoma on the left. The optic nerve was sharp O.U. with mid-to-moderate temporal pallor O.D. and severe temporal pallor O.S> and cup-to-disc of 0,5 O.D and 0.8 O.S. suggestive of Central scotoma. Further more, patient was required to undergo genetic testing for Leber hereditary optic neuropathy.
Please include genetic testing needed for Leber hereditary optic neuropathy
Discussion
Leber hereditary optic neuropathy