Abstract
Purpose :
To enhance AMD screening by improving the visibility of hyperpigmentation (HP) using near infrared (NIR) multiply scattered light imaging.
Methods :
We compared two datasets of non-mydriatic confocal and multiply scattered light images taken with the Digital Light Ophthalmoscope (DLO) (Aeon Imaging, LLC) using red (630 nm) and NIR (860 nm) light. The red and NIR dataset consisted of 21 subjects aged 48.2+/-15.3 yr, and 20 subjects aged 53.1+/-13.7 yr, respectively.
The DLO is a confocal retinal camera that projects illumination lines onto the retina that are synchronized to the readout of a CMOS rolling shutter camera. Multiply scattered light imaging is performed in real-time by applying leading and lagging timing offsets between the center of the illumination lines and detection aperture. The offsets were set to 0.5x and 1x the aperture widths of 51 and 102 micron for the red and NIR images, respectively.
DLO image frames were automatically registered, manually reviewed, and averaged. The coefficient of variation (CV) of the retinal background temporal to the OD macula was calculated in the confocal red and NIR images. HP was identified in 5 of the 20 NIR subjects. The Michelson contrast of the HP regions was computed for the NIR confocal, both offsets, and the mean of each leading and lagging offset pair.
Results :
Choroidal vessel contrast contributed to a higher mean CV using red vs. NIR light (0.14±0.05 vs. 0.07±0.03). In an example AMD subject, the max HP signal in red-light images was achieved with confocal imaging, at 4.2 standard deviations < the adjacent mean background. In the corresponding NIR images, the max HP signal occurred at a 102 micron offset, at 5.0 standard deviations < the mean. Averaging the NIR offset pairs suppressed shadowing caused by drusen, reducing the variation in the adjacent background and further increasing the HP signal to 11.1 standard deviations < the mean.
The Michelson contrast in the NIR images of the 5 HP subjects was 0.09±0.01, 0.07±0.01, 0.06±0.01, 0.10±0.01 and 0.10±0.01 in the confocal, 51 micron offset, mean 51 micron offset pair, 102 micron offset, and mean 102 micron offset pair, respectively.
Conclusions :
Real-time visualization of HP in the presence of nearby drusen can be improved by averaging the leading and lagging offset images. Averaging reduced distracting intensity variation in the adjacent retina while maintaining the Michelson contrast.
This is a 2021 ARVO Annual Meeting abstract.