Abstract
Purpose :
Current iris registration (IR) uses a scotopic eye image from the diagnostic device as a reference to register the photopic eye image from the laser device. However, iris distortions caused by pupil dilation and constriction may cause IR failure due to lack of matching iris features identified from the two images. This paper investigates IR using scotopic eye images and photopic eye images from the diagnostic device.
Methods :
This study included 60 eyes that underwent LASIK refractive surgery. Of the 60 eyes, there were 322 paired scotopic and photopic eye images simultaneously captured by iDesign Advanced WaveScan Studio system (AMO Development, LLC), and 60 eye images captured by STAR S4 IR® system (AMO Development, LLC). All images were analyzed to extract pupil and iris data with the image processing algorithms implemented on iDesign® system and STAR S4 IR® system. An IR test program, with the IR algorithms implemented on STAR S4 IR® system, was used to verify the IR functionality using scotopic or photopic eye image as reference to register the laser eye image. McNemar’s test was used to assess the significance of the difference in successful capture rates between the scotopic eyes and photopic eyes. A p-value less than 0.05 was used to demonstrate statistically significant difference between the results.
Results :
Compared to the scotopic eye image, the pupil size and the iris features in the photopic eye image are more similar to that in the eye image under STAR S4 IR® system illumination. IR capture rate with photopic eye images increases 5.92%, and this IR improvement on IR capture rate is statistical significant (p-value=0.0002). IR passes with photopic eye images are mostly based on circular fittings which provides more precise cyclotorsion angle (CT) compared to elliptical fittings. CT angles of laser eye images calculated from the IR using scotopic eye images is equivalent to that calculated from the IR using with photopic eye image with the compensation of the CT angle changes between the scotopic images and photopic images.
Conclusions :
IR with photopic eye images is more efficiency than that with scotopic eye images. Using both scotopic and photopic eye images as reference to register laser eye images can improve the IR capture rate with equivalent IR functionality.
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This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.