Abstract
Purpose:
To examine the relationship between retinal vascular parameters and optic nerve/ ganglion cell-inner plexiform layer (GC-IPL) parameters in non-glaucomatous eyes.
Methods:
Study subjects were identified from the Singapore Chinese Eye Study, a population-based survey of Singaporean Chinese aged 40 to 80 years. All subjects underwent standardized systemic and ophthalmic examinations. Retinal vascular parameters (retinal vascular calibers, fractal dimension, branching angle and tortuosity) were measured from retinal fundus photographs with a computer-assisted software (Singapore I Vessel Assessment, version 3.0) according to a standardized protocol. Spectral-domain optical coherence tomography (SD-OCT) (Cirrus version 6.0, Carl Zeiss Meditec, Dublin, CA) was used to measure optic nerve parameters (retinal nerve fiber layer [RNFL] thickness, rim area) and macular GC-IPL thickness. Non-glaucomatous was defined as eyes with normal, reliable visual field results.
Results:
173 non-glaucomatous subjects with gradable retinal photographs and OCT images were included for analyses. In multiple regression analyses, after adjusting for age, gender, mean arterial pressure, blood glucose, disc area, axial length, intraocular pressure & OCT signal strength; smaller fractal dimension (β=1.94, p<0.019), narrower retinal arteriolar caliber (β=1.73, p=0.027) & venular caliber (β=3.13, p<0.001) were independently associated with thinner average RNFL thickness. In addition, retinal arteriolar caliber (β=3.67, p=0.009) & venular caliber (β=6.28, p<0.001) were significantly associated with inferior RNFL but not with superior RNFL thickness (p>0.092). Smaller fractal dimension was independently associated with thinner average GC-IPL thickness (β=2.02, p=0.017), after adjusting for age, gender, mean arterial pressure and blood glucose. Retinal arteriolar caliber (β=2.33, p=0.015) & venular caliber (β=1.99, p=0.035) were significantly associated with inferior GC-IPL but not with superior GC-IPL thickness (p>0.228). Branching angle and tortuosity were not associated with optic nerve/ GC-IPL parameters.
Conclusions:
Our data demonstrated that smaller fractal dimension and narrower retinal vascular caliber were associated with optic nerve/ GC-IPL thinning in non-glaucomatous eyes. This information may be useful in further elucidating the role of vascular etiology in optic neuropathy.
Keywords: 629 optic nerve •
531 ganglion cells •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)