Vascular Displacement Outside the Optic Nerve Head in Glaucoma
Zahra Karjou, MD1 , Shahin Yazdani, MD1 *, Behrouz Alizadeh Savareh, PhD2
- Department of Ophthalmology and Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences
- Department of Medical Informatics, School of Management and Medical Education Sciences, Shahid Beheshti University of Medical Sciences
Abstract: Background: Vascular changes at the optic nerve head (ONH) have been well described in
association with glaucomatous damage and progression. The current study investigates
positional vascular changes outside the optic disc.
Methods: Methods: We utilized a database including 2,390 subjects with definite or suspicious glaucoma
undergoing serial stereoscopic fundus photography over a four-year period from 2015 to 2019.
Eyes with any pathology distorting the retina or its vasculature were excluded; eyes with
vascular changes only at the ONH were also excluded. Images were evaluated for vascular
changes at the ONH and within one disc diameter outside the disc border using Matlab
software. The software first performed vessel segmentation, followed by correction for image
scale, X-Y and rotation variability and finally quantified vessel displacement in pixels. The
amount of vascular displacement was measured as a function of disc diameter (DD), also
measured in pixels, and reported as a ratio.
Results: Results: A total of 23 eyes displayed significant vascular displacement outside the ONH while 60
eyes without such changes served as controls. Mean amount of vascular displacement was
0.15±0.01 versus 0.01±0.01 DD in cases and controls (p<0.001). Glaucoma had been diagnosed
in 20 eyes (87%) of cases and 35 eyes (58.3%) of controls (P= 0.014). Both at baseline and at
final visit, best corrected visual acuity was significantly worse (P=0.018 and P=0.032,
respectively) and cup-to-disc ratio (CDR) was significantly higher (P = 0.025 and P=0.04) in the
case group. During follow-up, significantly more eyes (69.6% versus 20%) in the case group
required surgery for poorly controlled glaucoma (P=0.001). A trend was observed for younger
age in the case group (54.5±16.5 versus 61.3±15.5 years, P=0.088).
Conclusion: Conclusion: Retinal vessel displacement outside the ONH is significantly associated with
glaucomatous damage; patients demonstrating such changes tend to have lower visual acuity,
higher CDR and require glaucoma surgery more often, indicating more significant disease
severity or progression.
