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R. Tumbar, A.E. Elsner, A. Weber, S.A. Burns; Large Field of View, High Resolution Scanning Laser Ophthalmoscope Using Adaptive Optics . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3548.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To image the retina with a relatively large field of view, adaptive–optics–based, high resolution, infrared scanning laser ophthalmoscope (AOSLO). Methods: We built an AOSLO capable of imaging the retina at high magnification with essentially diffraction limited performance. The optical train consists almost entirely of mirrors, minimizing unwanted reflections and rendering the system achromatic. The system images the retina over a field of view of +/– 10 deg with high magnification by varying the field position of a smaller imaging field. Because we steer the beam from the first pupil conjugate plane, we can obtain nearly diffraction limited performance over the entire +/– 10 deg range. The system is compact (fits on a 24"x24" breadboard). Focus for both ametropia correction (over +/– 20D) and for retinal sectioning is controlled by moving the entire system with a motorized positioner. Similarly to the field offset, the change in beam vergence is performed early in the optical train, eliminating the need to design most of the system for large angles arising from defocus. Our AOSLO uses different wavelengths for the adaptive optics and the imaging channels, which allows their use independently and also maximizes the throughput of both systems. In addition, the beacon beam used for wavefront sensing is inserted into the system after the deformable mirror, minimizing the effects of scattering from the mirror. The imaging wavelength is 830 nm to improve tissue penetration for imaging deep in the retina. Results: Images were collected for both tightly confocal and open confocal modes in 5 subjects. Without the AO system, highly magnified images were obtained without use of dilating drops for both modes. The highly confocal images show the expected images of peripheral cone photoreceptors. In open confocal mode, which increases the light return due to scattering, a number of additional structures are clearly visualized. These include regularly spaced structures, ranging in size from 30–50 microns. In an eye with numerous drusen, these structures are very clearly visualized. Conclusions: We have built a new adaptive optics imaging system that has a number of unique features. This system is very light efficient and provides excellent visibility of retinal structures at the cellular level in the living human eye.
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