Retinal Nerve Fiber Layer Thickness in Patients With Dominant Optic Atrophy (DOA) and Leber’s Hereditary Optic Neuropathy With DOA–Like Course

Abstract

Abstract: : Purpose: to analyze by optical coherence tomography (OCT) the retinal nerve fiber layer (RNFL) thickness in DOA and childhood–onset Leber’s hereditary optic atrophy (LHON) with a slowly progressive course simulating DOA. Methods: 12 patients with DOA (mean age: 26.4±12 years) and 8 with childhood LHON (mean age: 31.6±8.7 years) were compared to an age and optic nerve head (ONH) size–matched control group of 15 individuals. StratusOCT was used to detect the peripapillary RNFL thickness (RNFL thickness 3.4 acquisition protocol) and measure ONH size (Fast optic disc acquisition protocol). The eye with the worst visual acuity was selected in the patient group and compared to one randomly selected eye of subjects in the control group. RNFL thickness values and ONH areas were compared by one–way analysis of variance (ANOVA) with multiple comparison post test. Results: ANOVA revealed a statistically significant difference among the three groups in each measurement: 360° average (p<0.0001), temporal (p<0.0001), superior (p=0.0004), nasal (p=0.035) and inferior (p<0.0001) quadrants. Compared to the control group, patients with DOA showed decreased RNFL thickness values in the temporal (p<0,001), superior (p<0,001), nasal (p<0,05) and inferior (p<0,001) quadrants; those with childhood LHON revealed a significant RNFL thinning in the temporal (p<0,001) and inferior quadrant (p<0,05) and a trend towards reduced values in the superior one. No significant differences in ONH size were detected between patients with DOA (mean area: 1.898mm2) and childhood LHON (mean area: 1.942mm2) Conclusions: Both groups of patients show an identical loss of fibers in the temporal quadrant (papillo–macular bundle). However, a different pattern of RNFL loss in the other quadrants is revealed by OCT. In fact, cases with DOA show a diffuse and severe atrophy in all the remaining quadrants, whereas those with LHON only in the inferior sectors, closely resembling the clinical pattern of RNFL loss of acute LHON. The different patterns detected by OCT in our study may be related to differences in pathophysiology of DOA and LHON.

Keywords: neuro-ophthalmology: optic nerve • nerve fiber layer • mitochondria