Optical coherence tomography angiography (OCTA) is an noninvasive, rapid and reproducible technology which can provide high resolution view of the vascular structures and quantifies the vessel densities in retina and choroid. Myopia can be divided into simple myopia and pathologic myopia. The mechanism of myopia is not clear while it is closely related to the vessel density. For simple myopia, OCTA can monitor the course and deepen the understanding of myopia by quantifying the vessel densities in each layers and sectors and the foveal avascular zone. For pathologic myopia, OCTA has an advantage of observing the choroidal neovascularization, chorioretinal atrophy and Zinn-Haller arterial circle which can contribute to the early diagnosis and management and follow-up to estimate the prognosis. However, there are several limitations of OCTA which need to be improved, including in the process of acquiring high-quality images, accurate layering and dynamic observation.
Through the different image technologies, peripapillary atrophy can be classified into four types: α zone, β zone, γ zone and δ zone. Each type of them has different imaging and histological features. Peripapillary atrophy is a common structure in peoples’ eyes and it is correlated with many factors and diseases such as age, myopia, glaucoma, non-arteritic anterior ischemic optic neuropathy and age-related macular degeneration which bring difficulties to our diagnosis and antidiastole. Classifying and qualifying peripapillary atrophy properly, which can evaluate the changes and degrees, can benefit our studies about their mechanism and offer the clinical biological indictors and research basis.
Objective To observe the choroidal blood flow and morphological changes in patients with severe stenosis of internal carotid artery stenosis (ICAS). Methods A retrospective case-control study. Forty-six patients (46 eyes) with ICAS were enrolled in this study. There was severe stenosis in one side (the eyes in this side were set as case group) and mild or no stenosis in other side (the eyes in this side were set as control group). Color doppler ultrasound (CDI) was used to observe the changes of hemodynamic parameters of the ophthalmic artery (OA) and posterior ciliary artery (PCA), the main parameters of ultrasound Doppler imaging are peak systolic velocity (PSV), end diastolic velocity (EDV), resistance indices (RI) and the calculation of the pulsation indices (PI) through the use of a formula. Enhanced binarization of deep imaging coherence tomography (EDI-OCT) was used to measure the subfoveal choroidal thickness (SFCT). The total subfoveal choroidal area (TCA), luminal (LA), stromal (SA) and choroidal vascularity index (CVI) were obtained by modified image binarization technique. Results In the case group, the PSV in the OA and PCA was significantly lower than that of the control group (t=−2.200, −2.612; P=0.030, 0.011). There were no significant differences in EDV, RI, PI of OA (t=0.337, −1.810, −1.848; P=0.737, 0.074, 0.068) and PCA (t=−1.160, 1.400, 0.815; P=0.249, 0.165, 0.417). The SFCT (t=−3.711, P＜0.001), TCA (t=−2.736, P=0.007), LA (t=−3.188, P=0.002) and CVI (t=−2.096, P=0.039) of the case group was significantly lower than that of the control group. There were no significant differences in SA (t=−1.262, P=0.210) and LA/SA (t=−1.696, P=0.093). Conclusion In severe stenosis ICAS eyes, the PSV in the PCA and SFCT, TCA, LA, CVI are decreased.