Purpose: To examine the relationship between retinal vascular geometric parameters with retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) parameters in nonglaucomatous subjects.
Methods: Study subjects were identified from the Singapore Chinese Eye Study (SCES), a population-based survey of Singaporean Chinese aged 40 to 80 years. All subjects underwent standardized systemic and ocular examinations. Nonglaucomatous eyes were defined as eyes with normal, reliable visual field results. Retinal vascular parameters (retinal vascular fractal dimension, tortuosity, and caliber) were measured from retinal photographs by using a computer-assisted program, according to a standardized protocol. Spectral-domain optical coherence tomography (SD-OCT) was used to measure RNFL and macular GC-IPL thicknesses.
Results: A total of 352 nonglaucomatous subjects with gradable retinal photographs and OCT images were included for the final analyses. In multiple regression analyses, after adjusting for age, sex, hypertension, diabetes, axial length, disc area, and OCT signal strength; decreased retinal vascular fractal dimension (β = -1.60, P = 0.002), narrower retinal arteriolar caliber (β = -1.60, P = 0.001), and venular caliber (β = -1.97, P < 0.001) were independently associated with thinner average RNFL thickness. In addition, decreased retinal vascular fractal dimension (β = -0.77, P = 0.017) and decreased retinal venular tortuosity (β = -0.63, P = 0.042) were independently associated with thinner average GC-IPL thickness after adjusting for age, sex, hypertension, diabetes, axial length, and OCT signal strength.
Conclusions: Rarefaction, vasoconstriction, and straightening of the retinal vasculature are associated with thinner RNFL and GC-IPL thickness. This information may potentially provide further insights on the role of vascular processes in glaucoma development and progression.
Keywords: ganglion cell-inner plexiform layer; optical coherence tomography; retinal nerve fiber layer; retinal vasculature.