Pupil cycle time and its significance in patients with diabetic retinopathy

Abstract

Context: Prolonged pupil cycle time (PCT) is a complication of type II diabetes and becomes more protracted as the disease progresses. PCT can be used as a quick and accurate clinical test to determine how much autonomic neuropathy is influencing a diabetic patient’s pupil. Aims: The aim of the study was to compare the PCT of type II diabetes patients with that of the healthy control group and analyze the impact of several factors, including age, sex, duration of diabetes, and grade of diabetic retinopathy on PCT. Settings and Design: The study was conducted from August 2022 to August 2023. One hundred people were arbitrarily selected, 50 of whom had diabetes and 50 healthy controls. Subjects and Methods: To start rhythmic cycles of contraction and relaxation, a narrow, horizontally aligned beam of fixed proportions was focused on the inferior area of the pupil. The cycle period was then monitored in milliseconds using a handheld stopwatch. The mean PCT of diabetics was compared with nondiabetics and its correlation with different variables such as age, sex, diabetes duration, and grade of retinopathy was done. Results: Fifty diabetic patients (28 females and 22 males) aged 42–74 years and 50 controls (32 females and 18 males) aged 44–70 were included in the study. The mean PCT of the diabetics was 1130 ± 186 ms, whereas it was 940 ± 132 ms in the controls; thus, the mean PCT was longer in the diabetics. It was also found that the mean PCT increased with increasing grades of retinopathy. A positive correlation was also noted between mean PCT and duration of diabetes. Conclusions: PCT is a fast, simple, and reliable clinical test of optic nerve function. Being objective and quantifiable for each eye separately is a huge benefit. The PCT measurements might be used in the clinical evaluation of an autonomic nervous system. It is a simple, inexpensive yet quick, and effective tool to assess pupillary autonomic neuropathy in the diabetics.