Ocular and Hemodynamic Factors Contributing to the Central Visual Function in Glaucoma Patients With Myopia

Abstract

Purpose: The purpose of this study was to investigate the ocular and hemodynamic factors contributing to the central visual function in glaucoma patients with myopia.

Methods: This study was a prospective observational study, which included 236 eyes of 140 patients with normal-tension glaucoma (NTG), which includes 114 eyes with mild myopia (axial length ≥24 and <26 mm) and 122 eyes with moderate-to-severe myopia (axial length ≥26 mm). Ocular characteristics were axial length and posterior pole profiles, including peripapillary atrophy (PPA) to disc area ratio, disc tilt ratio, disc torsion, and disc-foveal angle. Hemodynamic factors included standard deviation of the mean of qualified normal-to-normal intervals (SDNN) of a heart rate variability (HRV) test and vessel density (VD) parameters from optical coherence tomography angiography (OCTA). The root mean square error was estimated as a measure of the VD fluctuation. Association between ocular characteristics and VD parameters of the OCTA with the central sensitivity of the 10-degree visual field or the presence of central scotoma were analyzed.

Results: Deep layer VD of the peripapillary and macular areas showed significant differences between mild and moderate-to-severe myopia (P = 0.034 and P = 0.045, respectively). Structural parameters, especially PPA to disc area ratio, had significant correlation with peripapillary VD parameters in myopic eyes. Lower SDNN value (ß = 0.924, P = 0.011), lower deep VD of the macular area (ß = 0.845, P = 0.001), and greater fluctuation of deep VD in the peripapillary area (ß = 1.517, P = 0.005) were associated with the presence of central scotoma in patients with glaucoma with myopia in multivariate logistic regression analysis.

Conclusions: The structural changes by myopia, especially in the peripapillary region, affected VD parameters in myopic eyes. Lower deep VD and greater VD fluctuation in the peripapillary region showed association with central scotoma in patients with glaucoma with myopia, suggesting both structural and vascular changes by myopia may be related to central visual function in glaucoma patients with myopia.

Figure 1.

Comparison of baseline vessel density and vascular fluctuation in each area according to the degree of myopia. Each image represents the results of three groups of myopia. As the degree of myopia gets greater, initial deep VD decreases in the peripapillary and macular area (A). However, the fluctuation of deep VD gets greater as the degree of myopia gets greater in absolute values (B) and percentage values (C).

Figure 2.

Three representative cases with distinctive features. The first and second images are binarized OCTA image of the deep retinal layers of the peripapillary area. We calculated vessel density fluctuation with these two images. The third images are the pattern deviation plot of the visual field exam of SITA 24-2. (A) A 57-year-old woman with low chorioretinal deep vessel density fluctuation shows a normal central visual field; (B) a 58-year-old woman with minimal chorioretinal deep vessel density fluctuation shows minimal central visual field defect; (C) a 56-year-old woman with moderate chorioretinal deep vessel density fluctuation shows obvious central visual field defect.