Peripapillary vascular density (pVD) and long-term measurement reliability in optical coherence tomography angiography (OCTA) were significantly lower in eyes with the tilted disc (TD). When controlling for other variables, disc tilt was still found to be a significant contributor to the pVD reduction in most areas. This research aimed to examine how sectoral pVD is measured by OCTA and how long-term measurement reliability is affected by optic disc tilt. In this case-control study that looked backward, 70 normal eyes were used for observation. The thickness of the peripapillary retinal nerve fiber layer (pRNFL) and the average pVD across 8 different retinal areas were measured using OCTA on two separate occasions separated by 1 year. The ovality ratio (longest/shortest disc diameter) on fundus photography was used to quantify disc tilt, with a TD defined as an ovality ratio of more than equal to 1.3 pVD. Researchers examined the pVD and pRNFL thickness in the TD and NTD groups. Intraclass correlation coefficients (ICCs) were calculated for both groups to evaluate their repeatability over time. Univariate and multivariate linear regression models were used to assess the significance of various risk factors for pVD. They found 35 cases of TD and NTD in the eyes. Average pVD was 47.0%±3.5% lower in the TD group than in the NTD group (51.7%±2.8% vs. 47.0%±3.5%, P<0.001). This trend was also true for all 8 industries. Average and sectoral pVD measures had reduced long-term reproducibility in the TD group (ICC: 0.46-0.83) compared to the NTD group (ICC: 0.67-0.96). After controlling for axial length, pRNFL thickness, and the OCTA image signal intensity index, disc tilt remained a significant predictor of pVD across the board and in all sectors, except for the inferior nasal sector. Eyes with TD had a smaller pVD and poorer long-term repeatability as evaluated by OCTA compared to NTD eyes. When trying to make sense of pVD as measured by OCTA, these results should be considered.

Source: journals.lww.com/glaucomajournal/Fulltext/2022/09000/Effect_of_Optic_Disc_Tilt_on_the_Measurement_of.11.aspx