Pupil cycle time and contrast sensitivity in type II diabetes mellitus patients: A pilot study

CONTEXT: Pupil cycle time (PCT) has been widely used for examination of ocular diabetic autonomic neuropathy (DAN). AIMS: The primary aim of this study was to evaluate the difference of contrast sensitivity according to PCT results, and the secondary aim was to determine the factors associated with PCT difference for type II diabetes patients. SETTINGS AND DESIGN: A clinical pilot study that included a total of 60 eyes of 60 type II diabetes patients. MATERIALS AND METHODS: We divided all patients into three groups according to PCT results. Group A and Group C were composed of patients who had upper one third PCT and lower one third PCT, respectively. We analyzed difference of age, diabetes duration, hypertension duration, mean best corrected visual acuity (BCVA), mean spherical equivalent (SE), HbA1C, glomerular filtration rate (GFR), stage of diabetic retinopathy, and Cardiac Autonomic Function Score (CAFS). Contrast sensitivity and decrease of visual acuity by glare were also estimated and analyzed for 28 eyes of 28 non-proliferative diabetic retinopathy (NPDR) patients. Group [NPDR] A and Group [NPDR] C were defined as those who had lower one third PCT and upper one third PCT, respectively. STATISTICAL ANALYSIS: Statistical analysis was done using SPSS 17.0 software. RESULTS AND CONCLUSIONS: Each group contained 20 eyes. Significant differences between Group A and Group C were observed in duration of diabetes and CAFS (P ≤ 0.001 and P <0.001, respectively). Contrast sensitivity in Group [NPDR] A was significantly more than in Group [NPDR] C at all cpds (all P ≤ 0.001). We found that PCT can influence contrast sensitivity or glare in diabetes patients and also confirmed a significant correlation of PCT with CAFS and duration of diabetes.