Real-time in-vivo imaging of marmoset photoreceptors based on adaptive optics incorporated differential interference contrast microscopy system

Abstract

Purpose : Since the retina cells are non-regenerating neuronal cells, detection at the early stage of cell degeneration is important. We developed an in-vivo optical imaging system incorporated with adaptive optics to obtain photoreceptor images in real time.

Methods : To image photoreceptors, we adopted differential interference contrast (DIC) microscopy composed of a polarizer, DIC prism, and analyzer. Also, to reduce the optical aberration from the eye, adaptive optics (AO) was combined with DIC microscopy. Light sources with the wavelengths of 623nm for cell detection and 840nm for AO were used. We performed in-vivo retina imaging in female adult marmosets (5y and 2y). The pupil in marmoset’ eye was dilated to obtain the stable optical path in in-vivo imaging. As imaging the retina cell layers, the marmosets were kept under anesthesia via 1-5% isoflurane inhalation. The photoreceptors in marmoset eye were imaged by charge-coupled device (CCD) detector [2752 x 2192 pixels]. Through a real-time AO feedback loop, the improved image was obtained every 0.5 to 1 second.

Results : The figure 1 is the image of the in-vivo photoreceptor layer of retina in the marmoset eye. The photoreceptor layer with circle shape photoreceptors in a mosaic pattern as reported in a previous study¹ was clearly observed by our system. From the size and pattern of photoreceptor, we could expect that the bright parts are cone cells. The curvature of eyes made the blurred area in the image around the outside. The field of view in the image was calculated about 14,000 μm². We observed that photoreceptors were densely and uniformly distributed in photoreceptor layer for the normal marmosets.

Conclusions : Conclusions: We imaged marmoset photoreceptors in-vivo with the DIC imaging system incorporated with AO. Retina layers were imaged in real-time in the feedback of AO correction.

1. Troilo, et al. Vision research. 1993; 33(10): 1301-1310

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Figure 1. in-vivo photoreceptor layer images of the normal marmosets. Scale bars: 20μm