Compact, modular and in-plane AOSLO for high-resolution retinal imaging

Abstract

The adaptive optics scanning laser ophthalmoscope (AOSLO) was first developed in 2002 and since then the technology has been adopted in several laboratories around the world, for both clinical and psychophysical research. There have been a few major design implementations of the AOSLO. The first used on-axis tilted spherical mirrors in a planar arrangement, and the second minimized the build up of astigmatism present in the first design by using a non-planar arrangement. Other designs have avoided astigmatism by using custom-made toroidal mirrors or by using lenses on-axis, rather than mirrors.We present a new design implementation for an AOSLO that maintains a planar optical alignment without the build up astigmatism using compact, reconfigurable modules based on an Offner relay system. We additionally use an off-the-shelf digital oscilloscope for data capture and custom-written Python code for generating and analyzing the retinal images. This design results in a compact system that is simple to align and, being composed of modular relays, has the potential for additional components to be added. We show that this system maintains diffraction-limited image quality across the field of view and that cones are clearly resolved in the central retina. The modular relay design is generally applicable to any system requiring one or more components in the pupil conjugate plane. This is likely to be useful for any point-scanned system, such as a standard scanning laser ophthalmoscope or non-ophthalmic confocal imaging system.

ERICA: Emulated Retinal Image CApture - A tool for testing, training and validating retinal image processing methods

“…Example images from a human participant collected from our AOSLO 83 and synthetic images generated for the same eccentricities - 1.5°, 3° and 6°. The synthetic images are generated with no noise, residual aberration or eye motion and so have better image quality than the human images.…”

“…To generate a realistic sampling pattern during fixation, eye movement would be added to the raster scan pattern, as described above. The scan pattern used in the simulation can be defined by the user and we use a model of the scanning mirrors in our AOSLO 83 . This data stream is then typically processed using the same desinusoiding algorithm that is applied to real, human-derived intensity data.…”

Simultaneous Optimisation of Confocal and Non-confocal Images in an AOSLO with a Reconfigurable Aperture Pattern

“…The detector module of the Oxford-AOSLO system [18] was modified as shown in Fig. 3 to collect both the confocal and non-confocal light simultaneously.…”

Is oblique scanning laser ophthalmoscope applicable to human ocular optics? A feasibility study using an eye model for volumetric imaging

“…As adaptive optics corrects the wavefront error caused by the aberration of the imperfect optics in the human eyes, both the lateral and axial resolution of an adaptive optics scanning laser ophthalmoscope (AOSLO) could approach the diffraction limits. The lateral resolution of AOSLO was revealed to be 2 to 5 μm, and the axial resolution was 37 to 84.2 μm for the human retina . Even though the axial resolution was improved, the volumetric imaging by AOSLO in the human retina was plagued by the need for the plane‐wise depth sectioning and a small FOV, typically within 1° to 2°.…”