Abstract
Objective To review retrospectively the electrophysiological and structural changes in 13 Chinese patients with Leber hereditary optic neuropathy (LHON). Methods 26 eyes of 13 patients with a genetically confirmed diagnosis of LHON were categorized into two groups according to the duration of the disease: group 1 (duration less than 3 months) and group 2 (duration between 3 months and 18 years). Clinical history, comprehensive visual electrophysiology, optical coherence tomography (OCT), and color fundus photography were performed. Results Fundoscopy showed optic disc hyperemia in group 1 and optic atrophy in group 2. OCT measures of retinal nerve fiber layer (RNFL) thickness around the optic disc and surrounding macula were normal in group 1 but reduced in group 2 (10 of 10 eyes). The thickness of the retinal ganglion cell layer (GCL) plus inner plexiform layer (IPL) surrounding the macula reduced significantly in group 1 and group 2 compared with a healthy control group. Pattern ERG (PERG) P50 amplitude was normal, but the N95/P50 ratio reduced in most of group 1 (4 of 5 eyes) and in all of group 2 (11 eyes). PERG P50 peak time was abnormally short in group 2. Multifocal electroretinography (mfERG) showed subnormal responses associated with ring 1 (the central area) and ring 2 in group 1 and reductions in rings 1, 2, and 3 in group 2. Conclusion The study highlights differences in retinal structure and function between the acute and chronic stages of LHON in a group of Chinese patients. There is PERG evidence of retinal ganglion cell dysfunction and OCT evidence of GCL + IPL thinning in both groups, but there is additional peripapillary RNFL loss in the chronic stage, associated with more severe RGC dysfunction. There is multifocal ERG evidence of localized macular dysfunction in both acute and chronic groups. The study highlights the importance of comprehensive electrophysiological and structural assessments of the retina in LHON and is pertinent to studies that aim to monitor disease progression or the effects of future therapeutic interventions.
Highlights
Leber hereditary optic neuropathy (LHON) was first described by eodor Leber in 1871 [1] and is one of the most common disorders caused by mitochondrial DNA mutation
Over 95% of LHON pedigrees harbor one of three mitochondrial DNA (mtDNA) point mutations (G3460A, G11778A, and T14484C), which all involve genes encoding complex I subunits of the mitochondrial respiratory chain [2]. e retinal ganglion cell (RGC) system is vulnerable to mitochondrial dysfunction, and optic atrophy is a frequent characteristic of mitochondrial and neurodegenerative diseases [3, 4]
Studies have examined the possible influence of an X-linked visual loss susceptibility locus, impaired mitochondrial respiratory chain Journal of Ophthalmology activity, mtDNA heteroplasmy, environmental factors, and autoimmune factors [5, 6]. e clinical characteristics of LHON are well documented [7,8,9,10], but fewer studies have compared visual electrophysiology with optical coherence tomography (OCT) of the retinal ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) in different stages of the disease. e aim of this study is to compare the retinal structure and function in both the acute and chronic stages of LHON in Chinese patients. e influence of the disease stage is examined by detailed OCT measures of macular and peripapillary retinal structure and by comprehensive electrophysiology, including pattern and multifocal electroretinography (PERG; Multifocal electroretinography (mfERG))
Summary
To review retrospectively the electrophysiological and structural changes in 13 Chinese patients with Leber hereditary optic neuropathy (LHON). OCTmeasures of retinal nerve fiber layer (RNFL) thickness around the optic disc and surrounding macula were normal in group 1 but reduced in group 2 (10 of 10 eyes). E thickness of the retinal ganglion cell layer (GCL) plus inner plexiform layer (IPL) surrounding the macula reduced significantly in group 1 and group 2 compared with a healthy control group. E study highlights differences in retinal structure and function between the acute and chronic stages of LHON in a group of Chinese patients. Ere is PERG evidence of retinal ganglion cell dysfunction and OCT evidence of GCL + IPL thinning in both groups, but there is additional peripapillary RNFL loss in the chronic stage, associated with more severe RGC dysfunction. Conclusion. e study highlights differences in retinal structure and function between the acute and chronic stages of LHON in a group of Chinese patients. ere is PERG evidence of retinal ganglion cell dysfunction and OCT evidence of GCL + IPL thinning in both groups, but there is additional peripapillary RNFL loss in the chronic stage, associated with more severe RGC dysfunction. ere is multifocal ERG evidence of localized macular dysfunction in both acute and chronic groups. e study highlights the importance of comprehensive electrophysiological and structural assessments of the retina in LHON and is pertinent to studies that aim to monitor disease progression or the effects of future therapeutic interventions
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