Retinal ganglion cell neurodegeneration in mitochondrial optic neuropathies: a comparative structural study

Abstract

AbstractPurpose to compare structural measurements of retinal degeneration between the most frequent hereditary diseases of retinal ganglion cells (RGCs), Leber Hereditary Optic Neuropathy (LHON) and Autosomal Dominant Optic Atrophy (ADOA).Methods Peripapillary retinal nerve fiber layer (RNFL) and retinal thickness (RT) were assessed by Spectralis OCT (Heidelberg Engineering, Germany) in 14 patients (28 eyes; age=37.57+16.43 years) with ADOA and 15 patients (30 eyes; age=29.27+13.27 years) with LHON (unaffected carriers with gene mutation). These data were compared with age‐matched control group. Statistical analysis was performed using Mann‐Whitney test at a significant level of p<0.05.Results ADOA group showed a significant reduction in RNFL (p<.0001 for all quadrants and average) and RT (p<.0001 for average, all quadrants and rings; except ring 1, p=.001), when compared with control group. LHON group yielded an increase in RNFL for inferior (p=.0051) and temporal (p=.0129) quadrants and for average (p=.0014); but a significant decrease in RT (temporal quadrant p=.0079; ring 1 p=.0016; ring 2 p=.0011; average p=.0283), comparing with controls. Comparing with ADOA group, LHON showed a significant increase in RNFL (p<.0001 for all quadrants and average) and also for RT (p<.0001 for all measures), except for ring 1 (no significant differences was found between study groups).Conclusion As expected, ADOA group presents a significant loss of peripapillar RGCs and consequently a significant reduction in RT. LHON group shows an increase in RNFL, which is consistent with a documented swelling of the papillomacular bundle. Surprisingly, we found a decrease in RT that suggests retrograde involvment of other retinal cell type.