Peripapillary vessel area density changes among glaucoma and non-glaucoma patients

Abstract

Purpose : Previously systemic and ocular determinants of peripapillary vessel area density (pVAD) among healthy subjects in the African American Eye Disease Study (AFEDS); and intraocular pressure (IOP) was not an independent determinant of pVAD. The current study reports determinants of pVAD in glaucoma subjects and tests the hypothesis that axial length (AL) is an effect modifier of the IOP – pVAD relationship in glaucoma subjects, who, presumably, have disturbed retinal autoregulation.

Methods : 6x6-mm optic disc optical coherence tomography angiography (OCTA) scans (CIRRUS HD-OCT 5000) were performed on participants of AFEDS, a population-based study of African Americans aged 40 years and older residing in Inglewood, California. Subjects with poor quality images were excluded. A multivariable linear regression model using GEE methods to control for inter-eye correlation was used to examine whether pVAD was independently associated with the following variables: IOP, retinal nerve fiber layer (RNFL), and AL. Covariates in the model controlled for signal strength (SS) and age.

Results : Of 2127 subjects with OCTA imaging, 1028 healthy subjects (1539 eyes) and 65 glaucoma patients (86 eyes) met our inclusion criteria. Lower pVAD was significantly associated with glaucoma, with the following mean ± sd. estimates: 0.346 ± 0.04 in healthy subjects vs. 0.263 ± 0.066 in glaucoma subjects (p = <0.0001). Restricting to healthy subjects after controlling for age and SS, significant predictors of lower VAD were longer AL (p < 0.001) and thinner RNFL (p < 0.001), but not IOP (p = 0.277). Among glaucoma patients, higher IOP (p = 0.017) and thinner RNFL (p = <0.001) were the only significant predictors of lower pVAD, controlling for age and SS. After stratifying by AL, higher IOP was significantly associated with lower pVAD among glaucoma patients with longer AL (> 24.2 mm = upper 33^rd percentile; p = 0.02), but not among those with shorter AL (≤ 23.22 mm; p = 0.454). IOP was not significantly associated with pVAD among healthy subjects in either AL stratum.

Conclusions : While IOP is not independently associated with pVAD among healthy subjects, higher IOP is associated with lower pVAD in glaucoma subjects. This relationship is stronger among glaucoma subjects with longer AL. These results support the hypothesis that disturbed retinal autoregulation is present in glaucoma subjects, and particularly among those with longer AL.

This is a 2020 ARVO Annual Meeting abstract.