BACKGROUND AND OBJECTIVE
To assess the consistency of digitization of 35-mm slides as practiced in ophthalmologic research and estimate the impact of variation on semi-automated retinal vessel width measurements.
PATIENTS AND METHODS
A single retina slide was repeatedly digitized under various conditions on three scanner models. Average color levels were extracted from the resulting images, from which vessel widths were graded. The color channel level variations and possible correlation with width were analyzed.
RESULTS
The Nikon 5000 scanner (Nikon Corp., Tokyo, Japan) had average coefficients of variation of 0.4, 2.3, and 0.5 for the red, green, and blue channel levels across all runs. The P values of the correlation between the red, green, and blue color channel levels and the width of the large retinal arteriole were .89, .27, and .58, respectively.
CONCLUSION
The results suggest that the tested scanners digitize the 35-mm slides in a reliable manner without biasing the retinal vessel measurements.
[Ophthalmic Surg Lasers Imaging 2010;41:60-66.]
AUTHORS
From the Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
Accepted for publication March 30, 2009.
Supported by the National Institutes of Health grant EY06594 (R Klein, BEK Klein).
The authors have no financial or proprietary interest in the materials presented herein.
The authors thank Mr. Scott Brandenburg, Ms. Holly Cohn, Ms. Lisa Grady, Ms. Mary Kay Aprison, and Ms. Heidi Gutt for their assistance.
Address correspondence to Karl Jensen, MBA, University of Wisconsin-Madison Department of Ophthalmology & Visual Sciences, 610 North Walnut Street, 442 WARF, Madison, WI 53726-2336.
doi: 10.3928/15428877-20091230-11
