Purpose:
The aim of this study was to investigate the applicability of a new adaptive optics scanning laser ophthalmoscope (AO-SLO) in patients with age related macula degeneration (AMD).
Methods:
A new lens based AO-SLO has been built and used to image various patients with AMD. The whole system is based on lenses enabling a reduction of aberrations introduced by the system itself (mainly caused by large angle scanning) in comparison to instruments based on spherical mirrors. Instead of using a separate laser beacon for wavefront measurements, the instrument uses part of the imaging light which is directed on a Shack-Hartmann wavefront sensor. The instrument incorporates a deformable mirror with 52 elements and operates at a line rate of 16 kHz that is translated to a frame rate of 10Hz. Variable scanning angles ranging from 1 to 5 degrees are supported by the system. Different scanning angles and the ability to image retinal cones in patients with AMD are investigated.
Results:
The figure shows a comparison of the cone mosaic in the macula between a healthy eye (left) and an eye with drusen (right). The images have an extension of ~3°x3°. Drusen appear in AO-SLO images as hyperreflective areas. Cone photoreceptors were visible in some areas of drusen. However, the signal to noise ratio of patient images is greatly reduced in comparison to healthy volunteers. This is either caused by opacities of the ocular media and/or residual wavefront aberrations.
Conclusions:
AO technology might help to get a deeper insight in the development of macular pathologies. The described AO-SLO system is capable to image, apart from healthy volunteers, patients with age related macular degeneration. The large scanning angle supported by the instrument simplifies a comparison with other imaging modalities.
Keywords: photoreceptors • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • age-related macular degeneration