Abstract
Purpose :
Laser speckle contrast imaging (LSCI) is able to reveal blood flow dynamics in the posterior segment noninvasively. The LSCI signal from the foveal avascular zone (FAZ) presents a unique opportunity to assess choroidal blood flow in an objective and standardized manner. To achieve this task, we employed a multimodal approach using a combination of spectral domain optical coherence tomography (SD-OCT) data and LSCI data to accurately identify the avascular foveal region and determine the choroidal blood flow velocity index (BFVi).
Methods :
SD-OCT and LSCI data of the macular region collected from 12 human eyes was retrospectively analyzed using the Heidelberg Spectralis (Heidelberg Engineering, Heidelberg Germany) and XyCAM RI (Vasoptic Medical, Inc., MD, USA) software. SD-OCT was used to identify the center of the fovea using both the axial OCT scans and the corresponding en face infrared image. This was then used to identify the corresponding location on the LSCI images. We measured and compared the mean and peak BFVi in three areas: the FAZ, a fixed-diameter region centered on the fovea (“macula”), and the overall field of view (“OFV”) (Figure 1). Paired t-tests were used to compare mean and peak BFVi between the 3 areas.
Results :
The average peak BFVi at the FAZ (7.5 ± 3.2 a.u.) was lower than that at the macula (8.8 ± 3.1 a.u.) (p< 0.05). There was no significant difference between macula and OFV blood flow (p=0.54). Similarly, the average mean BFVi was lower at the fovea (6.1 ± 2.5 a.u.) compared to the macula (7.2 ± 2.3 a.u.) (p< 0.05) and the OFV (7.2 ± 2.0 a.u.) (p < 0.05). There was no significant difference between mean BFVi in the macula versus the OFV (p= 0.87).
Conclusions :
We used multimodal imaging to accurately determine the location of the fovea and enable standardized estimation choroidal BFVi measurements. Further, we show that choroidal blood flow as measured in the FAZ is lower than blood flow as measured in larger macular areas that capture both retinal and choroidal blood flow.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.