Abstract
Purpose :
We recently reported a high-speed adaptive optics (AO) partially confocal ophthalmoscope using a digital micromirror device (DMD) and a high-speed 2D camera. Here, we have extended its functionality to perform simultaneous confocal, dark field, and split detection imaging with a single “multi-detection” camera configuration.
Methods :
The DMD, which is synchronized with the 2D camera, projects a series of AO corrected multi-line patterns on the retina for line scanning. Multi-detection mode images were reconstructed by adding or subtracting a set of spatially filtered subframe images from a single camera acquisition. Spatial filtering worked as a set of virtual line apertures, so the imaging mode could be easily switched by changing the spatial filtering size and position. In vivo retinal imaging was performed on a healthy subject after pupil dilation (1% tropicamide and 2.5% phenylephrine). We are currently running more subjects. Line patterns with four directions, 0°, 90°, ±45°, were tested, and the line separation was set to 85 µm on the retina to reduce crosstalk between neighboring illuminated fields. The field of view was 0.7°.
Results :
Multi-detection mode retinal images were acquired at two axial planes corresponding to the photoreceptor layer and the retinal vasculature from 1.5° to 6° temporal retina (TR). Figure 1 (a)-(c) show registered averages of the partially confocal, dark field and split detection images of the photoreceptor layer at 6° TR, respectively, reconstructed from the same subframe image set under horizontal line illumination. The reconstructed image frame rate was 250 fps. The partially confocal image shows cone and rod photoreceptors as bright spots, and dark field image shows a partial RPE cell mosaic. The split detection image shows the photoreceptor inner segment mosaic. The inner segment positions had a very high correlation with the cones shown in Fig. 1(a). Figure 1 (d)-(f) show corresponding images of vessels at 3.5° TR under vertical line illumination. The scale bar is 20 µm. Split detection imaging provided better visualization of vessel segments (pointed by arrows) invisible in Fig. 1(d).
Conclusions :
Here, we demonstrate that a high-speed AO partially confocal ophthalmoscope can be extended into a multi-detection mode ophthalmoscope providing confocal, dark field, and split detection images simultaneously from a single image acquisition by a single camera.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.