Assessment of anterior segment parameters under photopic and scotopic conditions in Indian eyes using anterior segment optical coherence tomography

PURPOSE: To compare the anterior segment parameters in photopic and scotopic conditions using anterior segment optical coherence tomography (AS OCT) in Indian eyes. MATERIALS AND METHODS: One hundred eyes of 100 normal subjects of both sexes, aged 19 to 76 years, underwent anterior segment evaluation by AS OCT (Visante™ OCT). Central corneal thickness (CCT), central anterior chamber depth (ACD), pupil diameter (PD) and the temporal and nasal peripheral irido-corneal angles were assessed in photopic and scotopic conditions. These anterior segment parameters were stratified for age, sex and refractive error. RESULTS: Mean values of the parameters measured in photopic and scotopic conditions respectively were as follows: ACD (mm) 2.88 ± 0.32, 2.89 ± 0.32 (P = 0.10); nasal angle (degrees) 28.80 ± 5.91, 22.28 ± 7.50 (P < 0.001); temporal angle (degrees) 29.95 ± 6.74, 22.82 ± 8.43 (P < 0.001); pupil diameter (mm) 4.08 ± 0.91, 4.68 ± 0.92 (P < 0.001); CCT (µm) 519 ± 33.88, 519 ± 33.88. CONCLUSIONS: There was no significant difference in the ACD in photopic and scotopic conditions. While the nasal and temporal angles showed a significant decrease, the pupil diameter showed a significant increase in scotopic conditions. Mean central ACD decreased with age and was shallower in females than in males. It was highest in myopes and lowest in hypermetropes. CCT was not influenced by photopic and scotopic conditions.