Background: Leber's hereditary optic neuropathy (LHON) refers to an optic nerve dysfunction due to mutations in the mitochondrial DNA, resulting in visual loss by apoptosis of retinal ganglion cells (RGC). In 20% of LHON cases, their fundus examination looks entirely normal at early stage. There are some reports regarding the circumpapillary retinal nerve fiber layer (cpRNFL) and the ganglion cell analysis around the macula in LHON patients and carriers by using optical coherence tomography.
Case presentation: A 40-year-old female complained of acute visual loss in both eyes. Her best-corrected visual acuity was 0.3 in the right eye and 0.2 in the left eye at the initial visit. Goldmann perimetry revealed bilateral central scotomas. Fundus examination and fluorescein angiography findings were normal, but decreased retinal inner layer thickness was detected around the macular area on spectral domain optical coherence tomography (SD-OCT). One month later, her visual acuity deteriorated to counting fingers in both eyes, and the thinning area of retinal inner layer spread rapidly. Suspected progressive RGC loss led us to check the possibility of LHON, with which the patient was diagnosed due to a positive result for the mitochondrial DNA (mtDNA) 11778 mutation. The ganglion cell complex (GCC) and cpRNFL thicknesses were observed for 24 months by using SD-OCT. The GCC thickness plunged sharply within 3 months followed by gradual decline until 6 months, thereafter showing a plateau up to 24 months. On the cpRNFL map, the temporal quadrant also showed the earliest thinning as seen in the macular area of the GCC map. The thicknesses of the superior, nasal, and inferior quadrants decreased gradually, keeping their normal ranges up to 6 months.
Conclusions: SD-OCT was a useful tool in the diagnosis and follow-up of LHON. The macular GCC thickness map may detect the earliest morphological changes in LHON, as well as the temporal area of cpRNFL, before funduscopic examination reveals optic nerve atrophy.