Abstract
Purpose:
To evaluate the sensitivity of the red reflex to tilt for different surgical microscopes.
Methods:
We analyzed the optical performance of three surgical microscopes: the LuxOR Ophthalmic Microscope (Alcon Surgical), OPMI Lumera T (Carl Zeiss Meditec), and the Leica M-501 (Leica Microsystems). We assessed the red reflex and its sensitivity to eye rotation. A 1-inch diameter PMMA sphere was machined into an eye model. An aspheric cornea designed to focus incident light onto the back-side of the sphere. In addition, an 8 mm diameter Coddington pupil were machined into the solid sphere with single point diamond turning. The area around the pupil was painted black to form an opaque mask of the pupil, while the back side of the sphere was painted red to provide a reflex similar to the eye. The eye model was mounted under each microscope on a tilt stage. Photographs of the red reflex for tilt angles ranging from 0 to 20 degrees were captured. Camera settings and lighting conditions were identical across the three devices. The captured images were analyzed in a photo-editing program. A square patch of pixels within the pupil was analyzed and the average of the pixel values within the square was used as a measure of the red reflex intensity.
Results:
For the red reflex, the LuxOR had the brightest reflex compared to the other two microscopes. Furthermore, the red reflex was nearly invariant with eye rotation for the LuxOR, whereas the red reflex from the Lumera and the Leica microscopes demonstrated a falloff in intensity, as well as crescent-shaped artifacts with increased rotation.
Conclusions:
We demonstrated a system for evaluating the optical properties of surgical microscopes. The LuxOR microscope also provided a red reflex that was highly insensitive to eye rotation when compared to the other two microscopes.
Keywords: 551 imaging/image analysis: non-clinical •
445 cataract •
549 image processing