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S.M. Steidl, N.J. Ellish, N. Moainie, C. Lin; The Effectiveness of a Nonmydriatic Camera for the Diagnosis of Diabetic Retinopathy . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3843.
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Since data show that about one third of diabetic patients do not receive yearly dilated eye exams, the use of telemedicine to take photos with a nonmydriatic camera may help identify people with diabetic retinopathy (DR) so that treatment can be initiated. The aim of this study was to validate the use of a nonmydriatic camera to diagnosis patients with diabetic retinopathy.
Diabetic patients were recruited from the retina clinic. Prior to having their pupils dilated, two digital photographs were taken of each eye using a nonmydriatic camera. After dilation, two additional digital photos were taken of each eye using the nonmydriatic camera, and two Kodachrome 35mm photos of each eye were also taken. Demographic data, as well as characteristics of the eye including fundus pigmentation, pupil size, and presence of cataracts, was also collected. A clinical eye exam was then conducted and retinopathy graded based on clinical assessment. At a later date, each image was assessed blindly and assigned a grade for both image quality and degree of DR.
The mean length of time with diabetes for the 43 enrolled patients was 13 years. Based on clinical diagnosis, 45% had no retinopathy, 29% had mild to moderate NPDR, 7% had severe NPDR, and 19% had PDR. Of the 39 patients that had photos available for review, there was a statistically significant difference in image quality between the undilated and dilated nonmydriatic photos, with better image quality with the dilated eye. Based on the subset of photos with sufficient image quality to allow a classification, there was no difference in grading of DR when comparing undilated to dilated nonmydriatic photos, or comparing either of these photos to clinical diagnosis.
There was a significant reduction in image quality of undilated nonmydriatic images compared to those images taken of a dilated eye, resulting in a significant decrease in the ability to assess DR. However, in patients where the image quality was sufficient to assess for DR, undilated and dilated images were essentially equal in grading of DR compared to each other and to clinical diagnosis. To increase the effectiveness of nonmydriatic photos of undilated eyes, it is important to identify factors, such as fundus pigmentation or pupil size, that can improve image quality.
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