Purchase this article with an account.
Nripun Sredar, Oladipo Emmanuel Fagbemi, Alfredo Dubra; Adaptive Optics Reflectance Confocal Scanning Light Ophthalmoscopy with Sub-Airy Disk Detectors. Invest. Ophthalmol. Vis. Sci. 2017;58(8):295.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To explore the change in transverse resolution with sub-Airy disk confocal detection pinholes in two adaptive optics scanning light ophthalmoscope (AOSLO) with different pupil sizes.
Two custom AOSLOs with superluminescent diodes (Superlum, Ireland) with peak wavelengths of 850 and 790 nm were used for wavefront sensing (12 μW average power) and reflectance imaging (60 μW average power), respectively. The photoreceptor mosaic of a subject with no known ocular pathology was imaged at the foveal center. Image sequences of 100 frames each were captured over 0.75° and 1.5° square field-of-view at a rate of 16 Hz in the AOSLOs with 7.75 and 4.3 mm diameter pupils at the eye, respectively. Thirty raw images were registered and averaged using a normalized cross-correlation method to compensate for eye movement and distortion due to the use of a resonant scanner and uniform temporal sampling. The confocal images were captured using pinhole diameters of 0.5, 0.6, 0.8, and 1.0 normalized Airy disk diameters (ADD) and co-registered. The images were compared both subjectively and through their radially-averaged power spectra.
The photoreceptor mosaic could be better resolved and a clear enhancement of the image high spatial frequency content could be observed with decreasing detector size. A higher-than-predicted signal reduction was also observed (up to 50%).
Sub-Airy disk confocal detectors can be used in reflectance AOSLO to improve resolution, despite a substantial reduction in signal. These findings are consistent with the trend predicted by the paraxial theory of linear confocal microscopy described by Wilson and Carlini (Optics Letters 12, 227-229 (1987)). Quantitative differences, most notably in signal reduction with decreasing detector size could be attributable to an imperfect correction of the aberrations of the eye.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Images of the photoreceptor mosaic at 1° from the foveal center captured with a custom AOSLO (4.3 mm pupil) with detector sizes 1.0 and 0.5 ADD. The images are displayed on a logarithmic scale. The photoreceptor mosaic is better resolved with decreasing detector size.
This PDF is available to Subscribers Only