"Setting the standard": an analysis of different acquisition patterns for macular OCT-angiography

This study aimed to determine the optimal OCT angiography (OCT-A) scanning pattern using the SPECTRALIS HRA-OCT2 device to evaluate macular microvasculature perfusion in healthy subjects.

Healthy subjects were imaged using the SPECTRALIS OCT-A Module (Heidelberg Engineering) with the following scanning protocols: 10ºX10º-512 ART 7 [P1], 10ºX10º-256 ART 5 [P2], 10ºX10º-512 ART 5 [P3], and 15ºX10º-256 ART 5 [P4], all centered on the macula. Vessel perfusion density (VPD) and vessel length density (VLD) of the superficial vascular complex (SVC) were calculated using ImageJ software to evaluate the differences between scanning patterns. Three additional 10ºx1º, ART 7 high-density images were also obtained using the in-built software (SP-X1701 Update 3, based on Heyex Software Version 1.9.215.0 H) in the macular area and the VPD and VLD for all the three10ºx1º pattern size images with the corresponding area of pattern 1 image[P1]. Two retinal specialists conducted a blind qualitative assessment of the foveal avascular zone and image quality.

Twenty eyes from 20 consecutive healthy patients were included in the study. The mean VPD for P1, P2, P3, and P4 were 35.60, 31.67, 31.18, and 31.16, respectively. Mean VLD for P1, P2, P3, and P4 were 7.54, 5.86, 6.74, and 4.40, respectively. Significant differences were found between P1 and the other patterns for both the VPD and VLD, but not between P2, P3, and P4. VPD and VLD for 10ºx1º high-density images were 33.20 and 4.61, respectively, with significant VLD differences compared to P1, but not for VPD. P1 scored the highest and P4 the lowest in the qualitative assessments.

The 10ºX10º-512 ART 7 pattern showed statistically significant qualitative superiority and appeared optimal for blood flow detection with reduced noise in quantitative assessments.