Abstract
Purpose:
To evaluate optic nerve head microcirculation in autosomal dominant optic atrophy (ADOA) patients with laser speckle flowgraphy (LSFG), a recently introduced method to assess blood flow.
Methods:
This study comprised 14 eyes of 8 ADOA patients (mean age: 37.7 ± 14.0 years; spherical equivalent: -3.66 ± 2.15 D; LogMAR visual acuity: 0.51 ± 0.39). Clinically, the ADOA patients were diagnosed by low visual acuity, pallid temporal optic nerve discs, visual field defects, a family history consistent with autosomal dominant inheritance and the presence of mutations in the OPA1 gene. Eighteen normal eyes of 9 age-matched subjects served as controls (mean age: 41.6 ± 12.7 years; spherical equivalent: -3.11 ± 1.75 D; LogMAR visual acuity: -0.14 ± 0.05). Blood flow in the optic nerve head was assessed with LSFG, and the mean blur rate (MBR) ratio was calculated for each optic nerve head quadrant (superior, temporal, inferior and nasal) by dividing tissue MBR in that quadrant by the entire tissue MBR in the optic nerve head. We then compared the MBR ratio in each quadrant in the two groups.
Results:
In all quadrants, MBR was significantly lower in the ADOA patients than in the controls (superior: 8.23 ± 1.50 vs. 13.84 ± 3.28; temporal: 5.12 ± 1.02 vs. 10.33 ± 2.48, inferior: 7.04 ± 1.31 vs. 13.65 ± 2.46, nasal: 8.70 ± 1.13 vs. 13.94 ± 2.32, respectively, p < 0.01). Only in the temporal quadrant, the MBR ratio was significantly lower in the ADOA patients (0.74 ± 0.09 vs. 0.82 ± 0.07, respectively, p < 0.05).
Conclusions:
In ADOA, the temporal optic disc generally appears pale in fundus imaging. This suggests that blood flow on the temporal side of the optic disc should be reduced compared to other disc areas, but precise measurements of blood flow in the optic nerve head of ADOA patients have not yet been reported. Here, we found that blood flow in the optic disc, particularly on the temporal side, was indeed significantly lower in ADOA patients than in normal controls. Due to the anatomical characteristics of the optic nerve, the papillomacular bundle is susceptible to damage caused by mitochondrial dysfunction, which occurs in ADOA. Thus, our results suggest that reduced blood flow in the temporal optic disc in ADOA patients is caused by damage to the papillomacular bundle.