Radial peripapillary capillary density in superior segmental optic hypoplasia measured with OCT angiography

BACKGROUND: To investigate the diagnostic power of radial peripapillary capillary (RPC) density, measured with optical coherence tomography angiography (OCT-A), in patients with superior segmental optic hypoplasia (SSOH). METHODS: Forty subjects with SSOH and 40 age- and axial length-matched control subjects were retrospectively registered for this study. SSOH was defined as intraocular pressure less than 21 mmHg with the presence of two of the following: superior rim thinning, superior entrance of the central retinal artery, scleral halo, and pale optic disc; as well as non-progressive visual field loss. RPC density was measured with swept-source OCT-A (Triton, Topcon) overall, in the quadrants, and in the 12 clock-wise sectors. Changes in RPC density were also compared in SSOH patients and age-matched patients with mild- or moderate-stage of glaucoma. RPC density was compared in pairs of groups with Welch’s t-test. Diagnostic power was assessed with the area under the receiver operating characteristics curve (AUC). RESULTS: Overall cpRNFLT was significantly different in the normal (106.7 ± 9.5 μm) and SSOH (77.2 ± 13.7 μm, p < 0.001) subjects. RPC density overall and in the superior, nasal, and inferior quadrants was significantly lower in the SSOH group (all, p < 0.001), but not in the temporal (p = 0.756) quadrant. The diagnostic power of RPC density was highest in the superior quadrant (AUC = 0.928) and the 1 o’clock sector (0.896). Comparing the SSOH and glaucoma patients showed that there were no significant differences in RPC density either overall (p = 0.391) or in the superior quadrant (p = 0.268), while RPC density was significantly higher in the inferior (p = 0.005) and temporal quadrants (p < 0.001) and lower in the nasal quadrant (p = 0.029). CONCLUSIONS: Low RPC density was found in the three non-temporal quadrants of the optic nerve head in SSOH patients, in comparison to normal subjects. Regionally, RPC density in SSOH was lower in the nasal quadrant and higher in the inferior and temporal quadrants in comparison to glaucoma patients. Measuring RPC density with OCT-A may help the diagnosis of SSOH and may improve the management of glaucoma.