Purpose
To demonstrate the imaging capabilities of a new multi-modal version of the compact Adaptive Optics Line Scanning Ophthalmoscope (AOLSO). High-resolution AO imaging of the retina, capable of resolving photoreceptors and other cells and structures in the eye, is an important new window on ocular health and disease. A new design of the compact multi-modal AOLSO line-confocal imager combines advantages of AOSLO with those of the AO fundus cameras for routine mapping of photoreceptor density..
Methods
The new multimodal adaptive optics imager (MAOI) incorporates a number of improvements in the optical design and the AO/focus control algorithms. The AOLSO uses <500μw of SLD illumination centered at 780nm (50nm FWHM) wih a cylindrical lens to generate line illumination, and AO-SDOCTuses SLD ~700 μW at 850nm (110nm FWHM). The system is currently configured for high-stroke DMs, a custom Shack-Hartman wavefront sensor, and an SDOCT spectrometer (Basler Sprint camera). MAOI has a compact footprint suitable for clinical application. The optical head measures ~30×45×20cm and is mounted to a standard slit lamp stand with chin/forehead rests. A field of up to ~3.5x5deg (1000x1500 pixels) is user-configurable with automated overlapping scan patterns in a 30deg field of regard for rapid montage. An integrated color LCD fixation display is included. LSO-based design allows video-rate (15 to 70 fps) high resolution retinal imaging with improved retinal navigation. Four normal adult volunteers ranging in age from 30 to 56 years, were imaged with a standard protocol (New England IRB-approved), and AOSLO image resolution was compared to that of prior designs.
Results
New multimodal system design and AO control significantly enhanced the capabilities and resolution of the AOLSO portion of the MAOI imager. Based on images acquired in resolution targets, optical resolution in the MAOI was measured to be ~1.8μm (referenced to the retina); currently somewhat more in the eye (~2.5μm), due to sampling at ~1μm/pixel to preserve light collection--a more than 50% improvement over the previous system. A small region within a single, unprocessed image is shown below (512x 716μm with fovea ~100μm off the lower right corner of the image).
Conclusions
The new compact MAOI resolves cones very near the fovea and can be used for automated AO montaging and photoreceptor density mapping in the macula.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
688 retina •
626 aberrations