Purpose: The aim of the study was to investigate iris alterations in diabetic retinopathy (DR).
Methods: Sixty-nine eyes of 69 patients were recruited and three groups of patients were examined: proliferative DR (n = 25), non-proliferative DR (n = 21) and healthy controls (n = 23). Macular optical coherence tomography (OCT), anterior segment iris OCT, and slit lamp digital camera photographs were taken. The thicknesses of the iris at a distance of 1 mm, 2 mm, and 3 mm from pupil margin were measured via iris OCT. Iris crypt count, furrow extent, color tone and collarette/diameter ratio were measured by means of anterior segment photography. Visual acuity, refractive error, intraocular pressure, and numbers of intravitreal injections were also recorded.
Results: The iris thickness measurements at 1 mm from pupil margin were significantly correlated with the macular thickness measurements (r = 0.32, p = 0.016). In the proliferative DR group, total number of injections were significantly correlated with the iris thickness measurements at 1 mm (r = 0.25, p = 0.04). The iris thickness measurements at distances 1 mm, 2 mm, and 3 mm from the pupil margin were similar in all of the groups (p > 0.05). Iris thickness did not correlate with age, intra-ocular pressure and collarette iris ratio in all the participants (p > 0.05).
Conclusion: Iris thickness is similar in diabetic patients and healthy controls. Meanwhile, iris thickness near the pupillary margin is positively correlated with macular thickness.
Keywords: Diabetic retinopathy; iris morphology; macular thickness.