Center for Laser Applications

CLA Vision Science Research

CLA supports many of the basic feasibility computations and measurements that result in proposals for external sponsorship of our applied research. Three of the vision science efforts of this past year will be described.

Auto-Analysis

CLA was provided a data base and images of clinical and eccentric PR examination results obtained by an ophthalmologist. The 360 patients ranged in age from 6 months to 18 years, and the PR device was an eccentric single-camera instrument that was maintained and operated by the ocular professional. A computer code was developed by CLA to analyze the binocular PR images. The average processing time is about 15 seconds per examinee. The analysis shows that these PR results can be categorized as: the positive group of 186 that requires referral has a predictive value of 98.9 % (i.e., only 2 false positives); the negative group of 144 cases of normal vision has a predictive value of 89.6% (15 false negatives); and an uncertain group of 30 images (or 8.3%) that need to be transferred to the reading center for resolution. The real-time analysis code reduces by about 92 % the need for electronic image transmission and manpower cost required for image evaluation and grading. A detailed comparison of these results and the recent clinical trial are in progress.

Simulation of human eyes

This theoretical research in developing physical models of the eye has broad applicability to the objectives of this focus area. The computational simulation of the performance of human eyes is complex because the optical parameters of the eye depend on many factors, including age, gender, race, and refractive status (accommodation and near-or far-sightedness), etc. This task is made more difficult, and interesting, by the diversity of the population of the U.S. and the inadequacy of the statistical characteristics of these parameters for our population.

Previously we simulated ametropic (near-or far-sighted) eyes that resulted from: variations in the axial length of the eye, the corneal curvature or power, and the intraocular refractive index gradient, as shown in the Figures 1 and 2. We have recently extended our investigation into the effects of higher-order wavefront aberrations (imperfections other than near-, far-sighted, and astigmatism corrections) and their coupling relationships with other conditions. In progress is the development of model eyes with the abnormalities of cataracts, floaters, keratoconus, corneal scars, and retinal tumors.

Dynamic Ocular Evaluation System (DOES)

Our experience has shown that the capabilities of current PR devices are deficient in important ways. Specifically, they do not satisfy the criteria for vision screening as stated by the American Academy of Pediatric Ophthalmologists and the American Academy of Pediatricians. CLA has designed a dynamic ocular evaluation system (DOES) that will satisfy these criteria and simultaneously perform high quality vision screening without requiring medical professionals and complicated manual procedures.

The system has a child-friendly LCD flat screen that displays animation video to attract the attention of the examinee throughout the required measurement procedures. The compact DOES optical portion, which includes the designed 2-dimensional light source display, a video camera, beam splitter, and infrared monitoring video camera, is assembled and fixed at the lower section of the flat screen. This portion of DOES is lightweight and is easy to position directly in front of the examinee. A laptop PC controls the DOES, including the optical and LCD elements. The trained operator will follow on-screen the user-friendly program and select an animation feature for the child. The infrared camera ensures that the child is properly positioned within the field-of-view of the detection camera. Development of this device is planned to be performed with the recently approved contract to the UTHSC and UTSI by the U.S. Army Telemedicine and Advanced Technology Research Center(TATRC).

Principal Investigators: Y.-L. Chen and J.W.L.Lewis Sponsor: CLA