Abstract
Purpose: :
A high–speed spectral domain optical coherence tomographer (SDOCT) was augmented with adaptive optics (AO) to provide high transverse resolution by correction of ocular aberrations. The system has the potential to provide improved resolution of retinal structures for disease diagnosis, vision studies, stimulus presentation, precision laser targeting, and studies of ultrafast laser damage mechanisms.
Methods: :
The system consists of SDOCT, AO, and line–scanning laser ophthalmoscope (LSLO) components. The SDOCT includes spectrometer optics, custom–designed with Zemax to achieve a theoretical spectral resolution of 0.1 nm, and a 2048–pixel linear array sensor capable of acquisition speeds up to 29 klines/sec. In practice, high density (1024×1024) images were acquired at 15–30 frames/sec without phase noise. The AO component consists of a Hartmann–Shack wavefront sensor and 4.4–mm, 141–actuator MEMS–based deformable mirror with a stroke of nearly 4–µm. The system also has a compact, integrated LSLO for simultaneous quasi–confocal en–face retinal imaging. The LSLO provides to the user in a wide field of view (up to 40–deg) rapid orientation of the location of the higher–magnification, cross–sectional SDOCT image. A custom DSP processor board is used to transform spectral signals to depth profiles in real–time and to control transverse scanning galvanometers. The system was characterized in a preliminary investigation on human volunteers with healthy eyes.
Results: :
The AO–SDOCT system was successfully demonstrated. The dual–imaging display and user interface enabled rapid positioning of the OCT beam for location of specific retinal features and advanced three–dimensional scanning modes. Static and dynamic aberrations were corrected at rates exceeding 1 Hz. AO–compensated images showed increased visualization of retinal layers compared to images without active compensation. The system design and performance will be discussed.
Conclusions: :
Active compensation of aberrations allows increased imaging resolution for earlier and improved visualization and more precise therapeutic or stimulus targeting of retinal structures. This technology will lead to new clinical and research advances for ophthalmology.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina