Multimodal analysis in symptomatic MIDD-associated retinopathy. A case report and literature review.

Purpose: To present results of contemporary multimodal ophthalmic imaging in a case of maternally inherited diabetes and deafness (MIDD) and a literature review of MIDD. Methods: A case of a 47-year-old female with diabetes mellitus, severe insulin resistance, familial lipodystrohy, deafness and increasing problems with vision is reported. A full ophthalmic examination was done, including best corrected visual acuity (BCVA, LogMAR), funduscopy, and imaging studies: optical coherence tomography (OCT), OCT angiography (OCT-A), fundus autofloresence (FAF), visual fields (HVF) 10-2 , electrophysiology (EP) and genetic testing were performed. Literature available on the topic was reviewed. Results: BCVA was 0.06 LogMAR in the right eye and 0.1 LogMAR in the left. Funduscopy revealed atrophy (AT) and pigmentary changes but no diabetic retinopathy. HVF confirmed corresponding defects. The imaging and diagnostic tests showed the following abnormalities: FAF: hypoautofluoresence in areas of AT and mottled appearance in the macular and peripapillary area; OCT: attenuation of outer retinal layers and retinal pigment epithelium (RPE) in the AT; OCT-A: thinning of the deep capillary plexus and choriocapillaris; EP: abnormalities on full field electroretinogram (ERG), 30 Hz flicker and single cone flash response; multifocal ERG: reduced responses; genetic testing: A-to-G transition mutation at position 3243 of the mitochondrial genome, typical for MIDD. After one year OCT ganglion cell analysis showed loss of thickness. Conclusions: Genetic testing should be considered in diabetic patients with pigmentary retinopathy. Imaging studies and diagnostic testing showed structural and functional retinal changes, confined to the macula and progressive in nature.

Reversible optic neuropathy secondary to metronidazole.

Metronidazole is a nitroimidazole antibiotic used in treating anaerobic bacteria and protozoal infections. It was first licensed for the treatment of Trichomonas vaginalis but is now used in the management of various gastrointestinal and genitourinary infections. Many neurological side effects are well documented, although there is scarce literature illustrating optic neuropathy secondary to metronidazole. We describe a case report of a 36-year-old man who presented with symptomatically reduced central visual loss on a background of a 2-year history of metronidazole use for a perianal fistula. Electrophysiology demonstrated bilateral optic neuropathy, with pattern visual evoked potential traces demonstrating marked latency and small amplitude responses of the P100 waves, which improved to within normal limits on cessation of metronidazole. This case study demonstrates clinical and electrophysiological reversibility of optic neuropathy secondary to high dose and prolonged metronidazole use.