Abstract:Our study demonstrates that vessel classification based on local color contrast can cope with inter- or intraimage lightness variability and allows consistent AVR calculation. We offer an open-source implementation of this method upon request, which can be integrated into existing tool sets and applied to general diagnostic exams.
“…Specifically, this region was between 1 and 1.5 disk diameters from the optic disk center. The vessels inside this region were segmented with the method presented by Bankhead et al 28 The width of the vessels was also estimated as in Bankhead et al 28 Vessel classification was performed by using the algorithm by Ivanov et al 29 For the necessary optic disk detection and segmentation of the optic disk border, the method of Dietter et al was used. 30 Figure 1 Example of an analyzed fundus photo.…”
Purpose
To compare changes in central retinal arterial equivalent (CRAE), central retinal vein equivalent (CRVE), arteriovenous ratio (AVR), tortuosity and fractal dimension in primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) and in a control group (CG) on fundus photographs. Further, to provide further evidence of vascular change in glaucoma patients using a novel method of tortuosity.
Patients and Methods
The primary endpoint was the change in CRAE, CRVE, AVR, fractal dimension and tortuosity of the retinal vasculature from baseline, retrospectively analyzed from 2011 to 2017 at the University Eye Hospital Tuebingen. Fundus photos of POAG (N = 49), NTG (N = 38) and CG (N = 18) were computer evaluated and analyzed in the quantities mentioned above.
Results
CRAE in NTG and POAG and CRVE in NTG significantly decreased (P = 0.02, P = 0.01; P = 0.03) whereas CRVE in POAG increased insignificantly (P = 0.72). In NTG, AVR decreased significantly (P = 0.05), but to a lesser extent than in POAG (P < 0.001). In CG, CRAE decreased insignificantly (P = 0.10), CRVE decreased significantly (P = 0.03) and AVR increased insignificantly (P = 0.77). In POAG tortuosity calculated using standard methods as well as our novel method, increased significantly (P = 0.015–0.04), whereas it did not occur in NTG (P = 0.18–0.57) and CG (P = 0.11–0.21). Fractal dimensions in POAG decreased significantly (P = 0.001–0.002), whereas in NTG and CG changes were insignificant (P = 0.33–0.92).
Conclusion
Based on a retrospective analysis of fundus photographs, specific retinal vasculature features of the retinal vasculature display significant alterations associated with NTG and POAG. The assessment of tortuosity using our novel method was consistent with previously established methods for analyzing tortuosity.
“…Specifically, this region was between 1 and 1.5 disk diameters from the optic disk center. The vessels inside this region were segmented with the method presented by Bankhead et al 28 The width of the vessels was also estimated as in Bankhead et al 28 Vessel classification was performed by using the algorithm by Ivanov et al 29 For the necessary optic disk detection and segmentation of the optic disk border, the method of Dietter et al was used. 30 Figure 1 Example of an analyzed fundus photo.…”
Purpose
To compare changes in central retinal arterial equivalent (CRAE), central retinal vein equivalent (CRVE), arteriovenous ratio (AVR), tortuosity and fractal dimension in primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) and in a control group (CG) on fundus photographs. Further, to provide further evidence of vascular change in glaucoma patients using a novel method of tortuosity.
Patients and Methods
The primary endpoint was the change in CRAE, CRVE, AVR, fractal dimension and tortuosity of the retinal vasculature from baseline, retrospectively analyzed from 2011 to 2017 at the University Eye Hospital Tuebingen. Fundus photos of POAG (N = 49), NTG (N = 38) and CG (N = 18) were computer evaluated and analyzed in the quantities mentioned above.
Results
CRAE in NTG and POAG and CRVE in NTG significantly decreased (P = 0.02, P = 0.01; P = 0.03) whereas CRVE in POAG increased insignificantly (P = 0.72). In NTG, AVR decreased significantly (P = 0.05), but to a lesser extent than in POAG (P < 0.001). In CG, CRAE decreased insignificantly (P = 0.10), CRVE decreased significantly (P = 0.03) and AVR increased insignificantly (P = 0.77). In POAG tortuosity calculated using standard methods as well as our novel method, increased significantly (P = 0.015–0.04), whereas it did not occur in NTG (P = 0.18–0.57) and CG (P = 0.11–0.21). Fractal dimensions in POAG decreased significantly (P = 0.001–0.002), whereas in NTG and CG changes were insignificant (P = 0.33–0.92).
Conclusion
Based on a retrospective analysis of fundus photographs, specific retinal vasculature features of the retinal vasculature display significant alterations associated with NTG and POAG. The assessment of tortuosity using our novel method was consistent with previously established methods for analyzing tortuosity.
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