Abstract
Purpose :
Choriocapillary blood flow is known to decrease in high myopia. This retrospective clinical study tested the hypothesis that myopic changes in the choroid already take place in low myopia. We therefor investigated the subfoveal choriocapillary blood flow in low myopia using optical coherence tomography angiography (OCT-A).
Methods :
We compared 78 eyes with low myopia with a control group of 79 age-matched healthy eyes, myopia being defined as a spherical equivalent refraction (SER) between -1 and -6 diopters. Quantitative measurements of the choriocapillaris (CC) were obtained at the central macula region (3 x 3 mm frame) using the RTVue XR Avanti OCT (OptoVue, Inc., Fremont, CA, USA) with AngioVue. CC flow signals were then compared between the groups. In addition, SER, axial bulbus length (AL) and subfoveal choroidal thickness (CT) were measured for correlation with CC flow. We also correlated CT to SER and AL. To account for correlated measurements within a subject we calculated a Generalized Estimating Equation with an interchangeable correlation matrix.
Results :
Correlation between lower CT and higher SER was significant (p=0.017). In addition, CT correlated negatively with AL (p=0.180). Subfoveal choriocapillary blood flow did not show any significant correlation with any of the parameters SER, AL or CT (p=0.772 and p=0.280 and p=0.816). Interestingly, the mean blood flow signal within the myopic group did not differ significantly from the mean flow signal of the emmetropic control group (p=0.258).
Conclusions :
Contrary to our hypothesis, choriocapillary blood flow seems to retain a constant level with increase in low myopia. The importance of choriocapillary blood flow regulation in myopic eyes warrants further investigation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.