Observations of Vascular Structures within and Posterior to Sclera in Eyes with Pathologic Myopia by Swept-Source Optical Coherence Tomography

Abstract

We examined the intrascleral and retrobulbar blood vessels in highly myopic eyes by swept-source optical coherence tomography (swept-source OCT). We included in the study 662 of 357 patients with pathologic myopia (spherical equivalent of myopic refractive error ≥ 8.00 diopters or axial length > 26.5 mm). A swept-source OCT system that uses a wavelength sweeping laser with A-scan repetition rate of 100,000 Hz and 1 μm wavelength was used. Radial scans along 12 meridians of 12 mm scan length centered on the fovea were made. Indocyanine green angiography (ICGA) also was performed to identify the intrascleral and retrobulbar vessels that were observed by swept-source OCT. Intrascleral and retrobulbar blood vessels were observed in the macular area of the highly myopic eyes. Linear hyporeflective structures running in the sclera were observed in 474 of the 662 myopic eyes, and ICGA confirmed that these structures were the long posterior ciliary arteries (LPCAs) or the short posterior ciliary arteries (SPCAs) whose entry sites into the eye were displaced toward the temporal edge of the posterior staphyloma in 50 eyes. In 36 of the 662 eyes (5.4%), cross sections of the blood vessels were seen coursing through the scleral layer. In 177 of these 443 eyes, the retrobulbar posterior ciliary arteries (PCAs) also were observed as a cluster of circular or curved hyporeflectant structures just posterior to the sclera. Swept-source OCT is a high-quality method to detect intrascleral and retroscleral blood vessels in the eyes with pathologic myopia. These findings and longitudinal studies of these vessels will help in investigating how they are altered in pathologic myopia, and how such alterations are related to the complications in the retina-choroid and optic nerve.