Purpose:
Retinal imaging modalities equipped with adaptive optics (AO) provides details of microscopic retinal structures by compensating the ocular aberrations. This paper aims at demonstrating the clinical utility of a custom-built high -speed, -penetration, and -resolution adaptive optics optical coherence tomography (HSPR-AOOCT) with Doppler detection functionality.
Methods:
Two eyes of 2 subjects were scanned by HSPR-AOOCT for photoreceptor imaging and choroidal blood flow measurement. HSPR-AOOCT possesses a depth resolution of 4.6 µm, and a scanning speed of 100,000 depth-scans/s. This enables high-speed volumetric scanning (typically 3 volumes/s). Because of the utilization of a probe at a wavelength of 1 µm, this system provides high-penetration tomography of the choroid. Furthermore, the adaptive optics mechanism cancels the aberration of the eye, and enables high transversal resolution (expected to be 3.6 µm). The photoreceptor imaging was performed at a speed of 3 volumes/s. The layers between nerve fiber layer (NFL) - inner plexiform layer (IPL), inner nuclear layer (INL) - inner/outer segment junction (ISOS), ISOS - posterior tips, retinal pigment epithelium (RPE), and choroid were averaged along the depth. For the choroidal blood flow imaging, B-scans with a scanning density of 695 depth-scans/degree were performed and Doppler detection was applied.
Results:
Photoreceptor cells were clearly observed in all 2 eyes over an eccentricity of 6 degrees, as shown in Fig. (A) and (B). The choroidal Doppler signals were detected beneath the RPE and observed in all 2 eyes of two subjects, as shown in Fig. (C) and (D).
Conclusions:
HSPR-AOOCT enabled depth resolved en face projection and choroidal Doppler flow tomography. However, the choriocapillaris were not clearly observed, presumably because of the high density of the choriocapillaris. Further improvement of AO performance could be a solution for this issue.
Keywords: photoreceptors • blood supply • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)