Optic disc microcirculation in superior segmental optic hypoplasia assessed with laser speckle flowgraphy

摘要

Superior segmental optic hypoplasia (SSOH) is a congenital anomaly of the optic nerve head (ONH). It is characterized by superior entry of the central retinal vessels, superior peripapillary scleral halo, reduced circum-papillary retinal nerve fibre layer thickness (cpRNFLT) and non-progressive inferior sector-like visual field defects. It is difficult to distinguish early normal tension glaucoma (NTG) from SSOH because both disorders have similar ONH configurations, reductions in cpRNFLT and other features (Fig. 1). However, it is clinically important to distinguish them. The pathogenesis of NTG remains unclear, but decreased ocular blood flow, including ONH microcirculation, rather than mechanical stress has been shown to be a promising explanation, in addition to oxidative stress and decreased axonal flow.4'5 Recent innovations in laser speckle flowgraphy (LSFG) have allowed us to monitor changes in mean blur rate (MBR) as optic microcirculation in the same eye and to compare parameters from MBR between eyes.5 Here, we determined the ability of LSFG measurements of ONH microcirculation and MBR to discriminate SSOH and NTG.