Abstract
Purpose :
A specular microscope is a commonly used non-contact device to image corneal endothelial cells. However the oblique imaging method to achieve specular reflection results in a deterioration (defocus) of the peripheral image capture area. We evaluate a prototype device that uses the Scheimpflug optical design for endothelial imaging that reduces image deterioration over the entire capture area.
Methods :
(1) Design: Based on the Scheimpflug principle, the objective lens was tilted with respect to the light receiving optical axis. The image capture area was 0.25 x 0.55 mm that is similar to the conventional device (CEM-530 by NIDEK).
(2) Evaluation of the prototype: A resolution chart was placed at each position in the image capture area, and each resolution was evaluated. Human eye images were also captured to compare them with the CEM-530.
Results :
(1) Design: The Scheimpflug optical system design can be implemented with a size that is consistent with current clinical devices (working distances of 40 mm or more). The Modulation Transfer Function (MTF) value at a spatial frequency of 160 cycles/mm is 0.2 or greater over the entire image capture area.
(2) Prototype evaluation: A spatial frequency of 250 cycles/mm on a resolution chart was resolved in the peripheral image capture area. Imaging of human eyes indicated reduced image deterioration (defocus) in the peripheral regions imaging area.
Conclusions :
A specular microscope that incorporates the Scheimpflug optical system can be produced for use in the clinical environment. The prototype device has provided high-resolution images over the entire capture area.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.