THE ROLE OF FREQUENCY DOUBLING TECHNOLOGY PERIMETRY IN EARLY DETECTION OF DIABETIC RETINOPATHY

The aim was to assess whether standard automated perimetry (SAP) and frequency doubling technology (FDT) perimetry are able to detect the effect of diabetes mellitus (DM) on retinal function in DM patients in the early stage of disease and to analyze which method is more specific and sensitive. A randomized cross-sectional study was conducted in three different groups of patients to compare the capability of these two methods to examine visual field and to detect the change in light sensitivity. Visual function was assessed in 60 adults with normal retinal finding, 60 adults with DM without clinically detectable retinopathy and 60 adults with DM and non-proliferative diabetic retinopathy but normal visual acuity. FDT perimetry and SAP were performed in all study patients. The presence and severity of diabetic retinopathy was determined by taking and evaluating two 50° field color photographs per eye, macula-centered and disc-centered. The following results were obtained by analyzing parameters in the groups of diabetic patients: sensitivity and specificity of SAP and FDT for medium sensitivity 86.7/33.3 (p<0.061) and 71.7/41.7 (p<0.228), respectively; for medium deficit 41.7/76.7 (p<0.063) and 65/50 (p<0.362), respectively; for loss of variance/pattern standard deviation (LV/PSD) 51.7/61.7 (p<0.536) and 61.7/51.7 (p<0.666), respectively; and for foveal sensitivity 81.7/36.7 (p<0.096) and 23.3/86.7 (p<0.839), respectively. Analysis of parameters between diabetics and control group yielded sensitivity and specificity for medium sensitivity 71.7/61.7 (p<0.001) and 70.8/55 (p<0.002), respectively; for medium deficit 56.7/60 (p<0.058) and 77.5/43.3 (p<0.037), respectively; for LV/PSD 58.3/58.3 (p<0.042) and 33.3/83.3 (p<0.437), respectively; and for foveal sensitivity 82.5/53.3 (p<0.001) and 28.3/85 (p<0.195), respectively. We concluded that neither of these methods was sensitive and specific enough to distinguish diabetics without retinopathy from diabetics with retinopathy. Both of these methods were highly specific and sensitive to distinguish diabetics from healthy subjects, but neither of these methods proved superior.