High Myopia Significantly Impacts Glaucomatous Changes to Deep Capillary Plexus Vessel Density

Macular vessel density loss occurs significantly faster in individuals with primary open-angle glaucoma (POAG) and high myopia than in people with POAG without high myopia, according to research published in Investigative Ophthalmology & Visual Science. 

Researchers conducted a prospective, longitudinal study evaluating the longitudinal changes in macular optical coherence tomography angiography (OCT-A) metrics in both superficial and deep capillary plexuses in this patient population. Specifically, investigators sought to determine whether baseline structural and functional measurements later impacted changes in macular OCT-A metrics.

The final cohort included 124 eyes: 63 eyes with POAG and high myopia (n=38) and 61 eyes with POAG without high myopia (n=42). All participants underwent a comprehensive ophthalmologic evaluation and imaging. Mean follow-up times were approximately 27.72 months ± 8.57 months for eyes with high myopia and 30.95 months ± 10.19 months for eyes without high myopia. All eyes received treatment with at least 1 type of antiglaucoma eyedrop. 

At baseline and throughout follow-up, there were no statistically significant differences in best-corrected visual acuity, intraocular pressure (IOP), mean IOP, mean deviation, and pattern standard visual field deviation, and disc hemorrhage. Significant differences, though, were noted in terms of baseline spherical equivalent, axial length, central corneal thickness, and average ganglion cell-inner plexiform layer thickness. 

The mean rate of vessel density change in the deep capillary plexus was “significantly faster” in eyes with POAG and high myopia compared with those without high myopia (-5.14% per year vs -3.71% per year; P =.008). The mean rate of vessel decrease in both the inferior and nasal sectors was also significantly faster in those with high myopia. Macular vessel density in the superficial capillary plexus, foveal avascular zone area, and foveal avascular zone circularity, however, were not significantly different between the 2 groups. 

Researchers also found that baseline whole image vessel density in the deep capillary plexus was associated significantly with whole image vessel density decrease over time in the deep capillary plexus in high myopia eyes (estimate, -4.03; 95% CI, -6.06 to -2.00; P <.001). 

Further analysis was conducted to examine the relationships between baseline sectoral vessel density and the rate of whole image vessel density decrease in the deep capillary plexus in eyes with and without high myopia. The investigators found significant associations between the rate of whole image vessel density decrease and baseline superior and inferior sectoral vessel density in high myopia in both univariate and multivariate analyses. Lower baseline whole image, superior, and inferior sectoral vessel density in the deep capillary plexus were all associated with a faster whole image vessel density reduction over time (whole image R², 31.1%; P <.001; superior sector R², 11.0%; P <.032; inferior sector R², 18.8%; P =.004). 

Study limitations include the inclusion of patients using topical ocular hypotensive medications, the use of 3 mm x 3 mm macular scans, and potential selection bias introduced by the use of only high-quality images. 

“These findings provided insights into the longitudinal effects of high myopia in retinal microvasculature, which can potentially be used in future clinical practice for risk assessment of myopic POAG progression by means of OCT-A and contribute to understanding POAG development and progression in the presence of high myopia,” the study concludes. 

Reference

Lin F, Li F, Gao K, et al. Longitudinal changes in macular optical coherence tomography angiography metrics in primary open-angle glaucoma with high myopia: A prospective study. Invest Ophthalmol Vis Sci. 2021;62(1):30. doi:10.1167/iovs.62.1.30.