OCTA Biomarkers Help Predict Visual Acuity Loss in Older Adults

Nicholas Siu-Kay Fung, MB ChB

Credit: The University of Hong Kong

A prospective cross-sectional study in Hong Kong suggests that common optical coherence tomography angiography (OCTA) parameters in adults aged 50 years and above can be useful biomarkers to predict deterioration in visual acuity (VA).¹

Results from the study showed that OCTA parameters including older age and female sex, as well as high foveal avascular zone (FAZ) area, low FAZ circularity, and low mean superficial vessel density (MSVD) in the outer ring, were independent, significant risk factors for reductions in VA.

“This is the first prospective cross-sectional and community-based study of this size providing a normative database on common OCTA parameters in Hong Kong citizens aged 50 and above, while also revealing its associations with best-corrected visual acuity (BCVA) and biomarkers predicting BCVA,” wrote the investigative team.

Led by Nicholas Siu-Kay Fung, MB ChB, Department of Ophthalmology, Li Ka Shing Faculty of Medicine, University of Hong Kong, investigators set out to assess the normative values and parameters of OCTA influencing BCVA in subjects recruited from an eye screening program in Hong Kong. The Southern District Signature Project Scheme within the Department of Ophthalmology offered complimentary eye examinations to all residents 50 years or older during the study period from May 2019 to December 2020, on a voluntary basis.

Clinical examination within the project included general health measurements, such as height, weight, calculated body mass index (BMI), and blood pressure, and participants were interviewed with structured questionnaires. The ocular examinations included measurement of BCVA using logMAR charts. Investigators then performed univariate and multivariate analyses to assess systematic factors and OCTA parameters associated with BCVA.

A total of 4188 eyes from 4188 participants were included in the analysis, with a mean age of 63.51 years and a mean BMI of 24.31 ± 3.79 kg/m². Data showed the mean BCVA logMAR was 0.06 ± 0.12, the mean FAZ area was 0.27 ± 0.37mm², and the mean FAZ circularity was 0.63 ± 0.12. Moreover, the MSVD of the included population was 14.48 ± 3.60 mm− 1, and the mean capillary perfusion density (MCPD) was 0.41 ± 0.06.

Upon multivariate analysis, the study indicated age (standardized regression coefficient (β) = .321; P < .001), male sex (β = -.089; P <.001), BMI (β = .039; P = .006), FAZ area (β = .039; P = .01), FAZ circularity (β = .034; P = .02), and MSVD (β = -.51; P <.001) were associated with BCVA.

Investigators noted an increasing age, BMI, and FAZ area showed associations with lower VA. Meanwhile, being male and having a higher MSVD and FAZ circularity in the outer ring was associated with increased VA.

Subgroup analyses suggested VD in the outer nasal and temporal quadrant were negatively associated with BCVA logMAR with statistical significance (β = -.226 and -.259; P <.001, respectively). On the other hand, CPD in the outer superior quadrant was positively associated with BCVA logMAR with statistical significance (β = -.123; P = .016).

“This reveals that as the VD in the outer nasal and temporal quadrant, and MCPD in the outer superior quadrant increases, BCVA increases,” investigators wrote.

References

1. Li, Y.K., Fung, N.SK., Chan, J.C. et al. OCTA biomarkers in adults aged 50 and above: a prospective and cross-sectional community-based study. BMC Ophthalmol 23, 71 (2023). https://doi.org/10.1186/s12886-023-02815-6