Vessel/perfusion density in two optical coherence tomographic angiography protocols: Interchangeable?

Different optical coherence tomography angiography (OCTA) scanning protocols evaluate the macula.

To compare the determination coefficients (R²) between vessel and perfusion densities of two OCTA scanning protocols in order to determine if their metrics could be interchanged.

Cross-sectional, prospective, comparative, observational, study between two OCTA scanning protocols (Angioplex, Zeiss) in healthy subjects. The R² between central, inner, and full densities (3 x 3 mm protocol) and between central, inner, outer and full densities (6 x 6 mm protocol) was identified, both for vessel and perfusion densities.

Seventy-eight eyes were evaluated; subjects' median age was 23 years. There were high R² between inner and full densities with the 3 x 3 mm protocol (0.96), between outer and full densities with the 6 x 6 mm protocol (0.96), and between central vessel and perfusion densities (≥ 0.96); R² between central vessel and perfusion densities of different protocols was ≤ 0.71.

Vessel and perfusion densities have high determination coefficients within a scanning protocol, but not between protocols, given that each one preferentially measures different macular areas. Metrics from different protocols should not be interchanged for follow up.