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S Olivier, AS Hafez, MC Boucher, MR Lesk; Entoptic perimetry and the Heidelberg Retina Tomograph as diagnostic procedures for diabetic macular edema . Invest. Ophthalmol. Vis. Sci. 2002;43(13):558.
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Purpose: To determine the sensitivity and specificity of entoptic perimetry and of the Heidelberg Retina Tomograph (HRT) as diagnostic procedures for diabetic macular edema. Methods: Thirty patients with diabetic retinopathy (10 without maculopathy, 10 with maculopathy but without significant macular edema and 10 with significant macular edema) as well as 10 non diabetic controls were prospectively enrolled. One randomly selected eye from each patient was submitted to entoptic perimetry using a white-noise field with a 30 Hz flickering frequency. Patients were instructed to fixate monocularly at the center of the monitor and to report any area looking different from the rest of the screen. The results were recorded as positive with the perception of any abnormal area. A dilated eye exam was then performed including contact lens macular examination. Each tested eye was finally submitted to imaging using the HRT version 2.01. A macular scan was performed and a 3 mm diameter circle centered on the fovea was drawn; based on a reference plane adjusted to the lowest point of the contour line, the volume above reference plane was calculated. Significant retinal thickening was defined as a volume above reference plane greater than the mean of normal patients plus two standard deviations. Statistical evaluation was performed, comparing each test to the accepted gold standard of contact lens macular examination. Results: The sensitivity value for entoptic perimetry was 90% and its specificity 83%. Sensitivity for HRT was 63% and specificity 72%. Of interest, the average values measured with HRT for the four clinical groups (non diabetics, diabetic retinopathy without maculopathy, maculopathy without significant macular edema and significant macular edema) showed a progressive increase in macular thickness but this trend did not reach statistical significance (p=0.31). Conclusion: Entoptic perimetry is a simple test with high sensitivity and specificity for the detection of significant diabetic macular edema. HRT scans using a 3 mm diameter circle centered on the fovea showed lower sensitivity and specificity values.
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