Optic Nerve Head Morphology Can Differentiate Dominant Optic Atrophy From Leber’s Hereditary Optic Neuropathy

Abstract

Purpose: : To analyze and differentiate by OCT the Optic Nerve Head (ONH) morphology and retinal nerve fiber layer (RNFL) thickness in patients with Dominant Optic Atrophy (DOA-OPA1) and Leber’s Hereditary Optic Neuropathy.

Methods: : We have investigated 20 patients with DOA which were positive for the presence of OPA1 gene mutations, 25 patients with classic (c) LHON, 8 patients with childhood (ch) LHON and 6 patients with slowly progressive (sp) LHON, also defined by a pathogenic mitochondrial DNA mutation. Stratus OCT was used to detect the peripapillary RNFL thickness (RNFL thickness 3.4 acquisition protocol) and measure the ONH morphology (Fast optic disc acquisition protocol). One randomly selected eye was considered for each patient and control individual. RNFL thickness values and ONH measurements were compared by one-way analysis of variance (ANOVA) and multiple comparisons post-hoc test.

Results: : The ONH analysis of DOA patients showed a significantly smaller optic disc area compared to c-LHON (p=0.004) and the same size compared to ch-LHON. Furthermore, the DOA patients showed a preservation of RNFL thickness values in all quadrants (average p<0.001, superior p<0.001, nasal p=0.04, inferior p=0.04), but the temporal compared to c-LHON and showed the same pattern of RNFL reduction with a better preservation of superior quadrant (p=0.02) compared to ch-LHON. Sp-LHON patients presented the same disc size of c-LHON and a better preservation of RNFL compared to the other group of patients.

Conclusions: : Our results indicate that DOA patients present a pattern of RNFL loss significantly milder and have a significantly smaller optic disc size compared to classic LHON. Nevertheless, DOA patients showed a pattern of RNFL loss and an anatomical conformation of ONH very similar to childhood LHON. Sp-LHON patients, although a clinical presentation suggestive of DOA, have a different pattern of mild optic disc involvement. ONH morphology can differentiate DOA and LHON. However, LHON subgroups with early onset may overlap with DOA in their ONH characteristics, suggesting some common steps in the pathologic mechanism.

Keywords: neuro-ophthalmology: optic nerve • optic disc