Abstract
Purpose :
Arterio-Venous ratio (AVR) is altered in patients with Branch Retinal Vein Occlusion (BRVO), but there is no objective measure to calculate the ratio. We developed an innovative purpose-built semi-automated software to objectively measure the AVR to determine Retinal Vascularity Index (RVI) and applied this software to compare RVI in the affected and fellow eyes of patients with BRVO with age-matched healthy controls.
Methods :
In a case-control study, fundus photographs of 140 patients with BRVO and 140 healthy controls were processed using our newly built software allowing analysis of arteriolar and venular calibres. The software automatically divided the fundus photo into four quadrants. The two largest arterioles and venules coursing through each zone were selected to analyze their calibres at four consecutive points between 0.5 and 1 disc diameters from the optic disc margin (Figure). RVI represented by AVR (= Mean Area of Arteriole/Mean area of Vein) was then generated for each point and extracted. RVI values thus obtained were compared with age-matched healthy controls.
Results :
The study included 420 eyes (140 BRVO, 140 fellow and 140 control eyes) of 280 subjects (mean age: 56.21 ± 11.11 years). AVR was significantly reduced in all four quadrants i.e., superotemporal (ST) (0.50 ± 0.24 vs 0.66 ± 0.32, p= 0.002), superonasal (SN) (0.47 ± 0.21 vs 0.50 ± 0.26, p= 0.01), inferotemporal (IT) (0.44 ± 0.22 vs 0.53 ± 0.33, p= 0.005) and inferonasal (IN) (0.40 ± 0.21 vs 0.53 ±0.24, p= 0.002) in BRVO eyes as compared to healthy controls. A significant reduction was also seen in AVR of fellow eyes: ST (0.44 ± 0.28 vs 0.66 ± 0.32, p < 0.001), SN (0.40 ± 0.20 vs 0.50 ± 0.26, p= 0.12), IT (0.45 ± 0.28 vs 0.53 ± 0.33, p < 0.001) and IN (0.45 ± 0.25 vs 0.53 ±0.24, p < 0.01) as compared to healthy controls.
Conclusions :
Affected and fellow eyes of BRVO patients show a reduction in AVR as compared to age-matched healthy controls. An innovative purpose-built semi-automated software can be used to study retinal vascular alteration in an objective manner and may unveil possible implications of retinal vascular pathology and its association with systemic vascular changes
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.