Age-Related Changes in Dynamic Iris Behavior Assessed Using a Programmable Closed-Loop Iris Control System.

Purpose: The purpose of this study was to develop and test a programmable closed-loop system for tracking, modulating, and assessing dynamic iris behavior, including in the mid-dilated position. Methods: A programmable closed-loop iris control system was developed by customizing an ANTERION OCT device (Heidelberg Engineering, Heidelberg, Germany). Custom software was developed to store camera and optical coherence tomography (OCT) images, track pupillary diameter (PD), control a light-emitting diode (LED), and modulate ambient lighting to maintain the iris in a dilated, constricted, or mid-dilated position in real-time. Study participants underwent 3 consecutive 65-second scan sessions. Dynamic iris behavior in the form of peak constriction velocity (PCV) and mid-dilated iris activity (MDIA) were calculated and analyzed offline. Results: Among 58 participants, 56 (96.6%) were eligible for analysis based on achieving and maintaining mean PD within ±10% of the calculated mid-dilated PD. Mean participant age was 49.8 ± 18.9 years. Mean PCV was 3.92 ± 0.83 mm/s, and mean MDIA was 0.37 ± 0.15 mm. The mean difference between the calculated and achieved mid-dilated PD was 0.166 ± 0.192 mm. There were significant negative correlations between PCV and age (slope = -0.022, P < 0.001) and MDIA and age (slope = -0.004, P < 0.001). Success rates were lower (69.0%) but relationships between dynamic iris behavior and age were similar based on achieving and maintaining mean PD within ±5% of the calculated mid-dilated PD. Conclusions: A programmable closed-loop iris control system can modulate dynamic iris behavior and maintain the iris in a mid-dilated position. Pupillary constriction velocity and iris activity in the mid-dilated position decrease with age. Translational Relevance: This system can be applied to study dynamic disease processes involving the iris and establish novel biometric measures that could serve as risk factors for acute and chronic primary angle closure glaucoma (PACG).

Intradevice Repeatability and Interdevice Agreement of Ocular Biometric Measurements: A Comparison of Two Swept-Source Anterior Segment OCT Devices.

Purpose: To assess the repeatability and agreement of ocular biometric parameters measured using the Tomey CASIA SS-1000 and Heidelberg ANTERION anterior segment optical coherence tomography (AS-OCT) devices. Methods: Both eyes of subjects 18 years of age or older were scanned three times with the CASIA and ANTERION under standardized dark lighting. One AS-OCT image along the horizontal (temporal-nasal) meridian was analyzed per eye and per scan. Pupillary diameter (PD) was within 15% for all pairwise comparisons. Anterior chamber depth, lens vault, anterior chamber width, angle opening distance, trabecular iris space area, and scleral spur angle (SSA500) were measured using manufacturer-provided image analysis software. Intraclass correlation (ICC), Wilcoxon signed-rank, and Bland-Altman analyses were performed to assess intradevice repeatability and interdevice agreement of measurements. Results: Thirty-two eyes of 21 subjects were analyzed. There was excellent agreement (ICC >0.98) and no significant difference (P > 0.05) in PD across all comparisons. Intradevice measurement repeatability was excellent for both the CASIA (ICC range 0.93-0.99) and ANTERION (ICC range 0.97-0.99). Interdevice measurement agreement was also excellent (ICC range 0.85-0.96). Measurements within and between devices were similar (P > 0.06) for all parameters except SSA500 (P = 0.03). Linear regression and Bland-Altman plots showed the relationship was consistent across the entire range of measurements. Conclusions: Intradevice measurement repeatability is excellent for the CASIA and ANTERION. Interdevice measurement agreement between the two devices exceeds metrics reported by previous comparison studies. Translational Relevance: Modern swept-source AS-OCT devices produce highly repeatable measurements of ocular biometric parameters that are nearly interchangeable across devices.