Purpose:
Rodent models of human eye disease have significantly increased the demand for in vivo animal fundus imaging modalities with cellular resolution. The small eye of the mouse provides among the largest NA of any mammal eye, and has the potential to provide superior retinal image resolution, However, due to the optical properties of mouse eyes, there are few viable methods for high resolution in vivo imaging which can exploit the arge NA anywhere in the eye while isolating selected layers for precision daptive optics (AO) correction. Large aberrations and defocused layers in thick" retinas render conventional wavefront sensing technology difficult.
Methods:
A high dynamic range pupil-scanning wavefront sensor method incorporating AO imaging data and GPU processing was tested; because of the stability of anesthetized animals, requirements on imaging scan rates and AO loop closure rates are much less stringent. Serially scanned low lenslet density wavefront sensors (Shack-Hartman combined with a variant of laser ray tracing) have no spot overlap issues, with computer controlled spot density over the pupil so that successive AO corrections can be made over very large defocus ranges. The system used 112fps GX1050 dual Ethernet camera (Prosilica) and a AO-SDOCT platform with a 5.5µm stroke DM (Boston Micromachines Corp.) A sliding badal optometer locks the OCT reference arm and sample arm so the 50D of sphere correction can be made with no shift of the OCT images. The PSWS was implemented in this test bed.
Results:
The system was tested in a Sprague-Dawley rat. The 790nm beacon was used in the pupil-scanning configuration with one pinhole and lens -in effect the extreme case of one lenslet! The scan of 25 x 25 spots over a 3mm pupil took ~5.5 s. The spots in the uncorrected rat eye were much larger than a SHWS could accommodate (>1mm). The centroid of each spot was computed and assigned as slope vectors to the pupil grid to generate high dynamic range WS data. OCT images and their corresponding WS data at the badal sphere indicated in diopters are shown in the figure.
Conclusions:
The use of animal models and new cellular resolution imaging tools will continue to be an important part of new research, from basic vision research to commercial drug discovery.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • aberrations • optical properties