Abstract
Purpose :
To visualize pathology related to inherited retinal dystrophies (IRD) with single-shot wide-field structural OCT and OCT angiography (OCTA).
Methods :
Subjects were imaged with a 1050-nm central wavelength 500-kHz swept-source OCTA prototype developed by our group. This device achieves 10.4 µm lateral optical resolution and 5 µm axial resolution in a 12 (fast axis) × 23 (slow axis)-mm (1536 A-scans per B-scan; 2304 B-scans acquired with 3 repeats) field of view. Flow was detected using a highly sensitive phase-stabilized complex-decorrelation approach. A bi-directional graph search method was used to extract layer boundaries for the inner retina, ellipsoid zone (EZ), retinal pigment epithelium (RPE), choriocapillaris (CC), and choroid. En face images of the retinal and choroidal layers were produced by using either mean (for structural) or maximum value (for angiographic) projection between these boundaries. We also acquired fundus autofluorescence (200Tx; Optus, PLC) images of the same eyes for comparison.
Results :
In our study, 30 scans were obtained from 18 subjects, with 12 subjects having both eyes scanned and 6 subjects having one eye scanned. IRDs included retinitis pigmentosa (RP) and choroideremia. In cases with RP, we found more extensive degeneration in the EZ relative to the RPE by comparing structural OCT en face images of the resepective layers (Figure 1). CC defects were also observed in the early stage of the disease while the overlying RPE was still intact (Figure 1). In cases with choroideremia we found that the most preserved structure is the RPE, followed by the EZ, with the CC exhibiting relatively more degeneration (Figure 2). In both cases, we observed degeneration in peripheral regions of the retina and choroid. We additionally found that structural OCT can detect the presence of the RPE in the absence of lipofuscin observed in FAF images.
Conclusions :
Wide-field swept-source OCT/OCTA can characterize IRD-related pathology including EZ, RPE, and CC loss outside of conventional OCT fields of view. Characterization of such features has the potential to enhance our understanding of pathophysiological and therapeutic research.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.