Abstract
Abstract: :
Purpose: The design and initial testing of a tracking adaptive optics scanning laser ophthalmoscope is presented. Methods: A retinal imaging/tracking system (tracking scanning laser ophthalmoscope, TSLO) was incorporated into an adaptive optics scanning laser ophthalmoscope (AOSLO). The active, hardware–based retinal tracker drives slave mirrors in the AOSLO at conjugates to the center–of–rotation resulting in line–of–sight (i.e., simultaneous retinal and pupil) tracking. This configuration also allows for the correction of small head movements with the potential elimination of the bite bar. The system provides two SLO images: a wide–field (34–deg) retinal image and a high resolution, high magnification (2 deg) AO image. This will allow clinicians to easily position the AOSLO scan in a drag–and–drop manner. A MEMS–based deformable mirror (Boston Micromachines Inc.) was used for wave–front correction. The AOSLO uses a novel optical design that consists of spherical mirrors in an arrangement designed to achieve a reduction in astigmatism among other system aberrations. Normal adult human volunteers were tested to optimize the tracking instrumentation and to characterize AO imaging performance. Results: The AO optical design achieved an error of <0.5 waves (at 800 nm) over ±6 deg on the retina. The third generation retinal tracking system achieved a bandwidth of greater than 1 kHz allowing acquisition of stabilized AO images. Other advanced features such as real–time image averaging and an algorithm for automatic blink detection and tracking re–lock were also tested. Conclusions: The retinal tracking system significantly enhances the imaging capabilities of the adaptive optics scanning laser ophthalmoscope. The TAOSLO has the potential to provide the capabilities for automatic mosaic generation, precise delivery of stimulus or therapeutic laser beams, and long integration time detection of weak retinal reflectance and fluorescence for advanced diagnostic applications.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • eye movements: recording techniques • imaging/image analysis: non-clinical