Imaging: Clinical Science
- Ophthalmic Surgery, Lasers and Imaging
- May/June 2012 - Volume 43 · Issue 3: 196-204
BACKGROUND AND OBJECTIVE:
To investigate near infrared iris transillumination (NIRit) imaging as a new method to quantify pupil shape, size, and position because the imaging modality can uniquely provide simultaneous information regarding iris structural details that influence pupil characteristics and because exploration of related techniques could promote discovery helpful to clinical research and care.
PATIENTS AND METHODS:
Digital NIRit images of normal and diseased eyes were used along with computer-assisted techniques to quantify four primary pupil parameters, including pupil roundness (PR), pupil ovalness (PO), pupil size (PS), and pupil eccentricity (PE). A combined measure of PR and PO was also developed (the pupil circularity index [PCI]). Repeatability of the measures was studied and example analyses were performed.
Pupil measures could be calculated for right eyes of 307 subjects (164 normal, 143 other), with fewer than 0.5% exclusions due to image quality. Repeatability study did not show significant bias (P < .05) for any of the four primary measures. Example analyses could show age-associated differences in pupil shape (⩾ 50 year olds had less regular pupils than < 50 year olds: median PCI = 0.009 vs 0.006; P < .01) and that a group of pigment dispersion syndrome subjects (n = 27) had less regular pupils than a group of matched controls (PO = 0.9966 vs 0.9990; P < .05).
Digital NIRit imaging can provide novel, reliable, and informative methods to quantify pupil characteristics while providing simultaneous information about iris structure that may influence these parameters.
From Illinois Eye Institute (DKR), Illinois College of Optometry, Department of Clinical Education; Illinois Institute of Technology (YY, ASL, MNW), Department of Electrical and Computer Engineering; Predictek, Inc. (YY, ASL, MNW); University of Illinois at Chicago (DKR, MNW, ASL, JTW), School of Medicine, Department of Ophthalmology and Visual Sciences; and University of Illinois at Chicago (DKR), School of Public Health, Division of Epidemiology and Biostatistics, Chicago, Illinois.
Presented in part at the annual meeting of the Association for Research in Vision and Ophthalmology, May 2–6, 2010, Fort Lauderdale, Florida.
Supported by National Eye Institutes Grant EY015604 (AL, YY, MNW).
Dr. Wernick is President of Predictek, Inc., a company that has been the recipient of an NIH/NEI SBIR grant (EY015604) for development of infrared technology for ophthalmic examination. Drs. Lukic and Yang are employees of Predictek, Inc., and Drs. Roberts and Wilensky have consultant roles on grant EY015604. Drs. Roberts, Wernick, Lukic, and Yang have potential financial interests as patent holders related to infrared imaging technology.
Address correspondence to Daniel K. Roberts, OD, PhD, Illinois Eye Institute, 3241 S. Michigan Avenue, Chicago, IL 60616. E-mail: firstname.lastname@example.org
Received: March 09, 2011
Accepted: January 13, 2012
Posted Online: March 01, 2012