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Infrared Imaging Technique may Help Demonstrate Iris Transillumination Defects in Blacks who Show Other Pigment Dispersion Syndrome Clinical Signs

Roberts, Daniel K. OD, MS*; Wernick, Miles N. PhD† ‡

doi: 10.1097/IJG.0b013e3181405e72
Original Studies
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Purpose Pigment dispersion syndrome (PDS) is considered to be rare among blacks, although the inability to detect iris transillumination defects (ITDs) among very darkly pigmented irides could diminish the clinician's commitment toward the PDS diagnosis due to uncertainty brought on by the lack of this clinical sign. The goal of this study was to investigate the potential utility of a new infrared (IR) imaging technique to demonstrate ITDs among a group of blacks whose initial PDS diagnosis had to be based on pigment dispersal signs other than iris transillumination.

Methods A previously described digital camera system, modified to detect visible and IR light, was used to image the irides of 10 blacks (20 eyes, 8 females, 2 males; age range=51 to 67 y) considered to have PDS on the basis of the clinical signs not including the presence of ITDs as detected with traditional slit lamp examination. Only 1 eye of 2 different subjects had ITDs that were detected with slit lamp examination, but these consisted of a very small, isolated ITD of questionable importance in each of the eyes. Normal control eyes that were matched according to age, race, sex, and refractive error were also photographed, and 2 glaucoma specialists independently reviewed PDS/control eye pairs in a masked fashion. They were instructed to select the eye more likely to be the PDS eye without the benefit of clinical information other than the digital transillumination characteristics.

Results Observer no. 1 correctly selected the PDS eye among 19 of 20 (95%) PDS-normal eye pairs, and observer no. 2 correctly selected the PDS eye among 15 of 20 (75%) matched pairs. On the basis of these results, it was unlikely that observer no. 1 (Fisher exact test, P<0.0001) or observer no. 2 (P=0.06) selected the PDS eye IR image due to chance alone. It was also unlikely that selection agreement between the 2 observers was due to chance alone (κ coefficient=0.58).

Conclusions Digital IR iris photography may help demonstrate abnormal ITDs among the darkly pigmented irides of blacks who have signs of pigment dispersal but who do not have detectable ITDs with traditional slit lamp examination. Infrared iris examination with newer methods should be studied further relative to blacks and others because useful clinical and/or research oriented information could be gained.

*Illinois Eye Institute, Illinois College of Optometry

Department of Electrical and Computer Engineering, Illinois Institute of Technology

Predictek, LLC, Chicago, IL

Grant Support: Supported in part by research grants (D.K.R.) from Fight-for-Sight (formerly the Fight-for-Sight Research Division at Prevent Blindness America), the Illinois Society for the Prevention of Blindness, and the Illinois College of Optometry Research Allocation Committee.

Disclosures: Miles N. Wernick is President of Predictek, Inc, a company that is the recipient of an NIH/NEI Small Business Innovation Research (SBIR) grant (EY015604) and is involved in the development of infrared technology for ophthalmic examination. Infrared technology developed by Predictek was not used in this current investigation. Daniel K. Roberts has a consultant role on grant EY015604.

Reprints: Daniel K. Roberts, OD, MS, Illinois Eye Institute, Illinois College of Optometry, 3241 S. Michigan Avenue, Chicago, IL 60616 (e-mail: droberts@eyecare.ico.edu).

Received for publication August 17, 2006; accepted November 17, 2006

© 2007 Lippincott Williams & Wilkins, Inc.