Purpose: To objectively quantify dynamic changes in lens shape during accommodation using two-dimensional OCT images
Methods: In-vivo responses to an accommodative step stimulus of three subjects (aged 22, 39, and 45) were captured using a custom-made extended-depth SD-OCT system operating at 840 nm following an IRB-approved protocol (Ruggeri et al. 2012). Subjects focused on a visual accommodation target designed to produce an adjustable step stimulus of accommodation. Accommodative responses to 2-D and 4-D stimuli were captured ~1.5s before and ~4.5s after stimulation. Lens thickness, anterior curvature, and posterior curvature were measured using a newly-developed algorithm (validated using a calibration sphere). Dynamic changes in lens thickness and curvature were then fitted with an exponential model to produce time dependent constants.
Results: All calibration OCT images were automatically analyzed in under 2 seconds. A radius of 7.793mm ± 0.051mm was calculated resulting in a difference of 2.4μm from the reported nominal value of the calibration sphere. Anterior lens radius decreased over time in all subjects. Radius of the posterior lens experienced a slight increase for all subjects.
Conclusion: This study demonstrates the feasibility of quantifying the dynamic changes in lens curvature and thickness during accommodation using extended-depth OCT combined with a step accommodation stimulus and an automated segmentation algorithm.
Siobhan Williams, Giovanni Gregori, Marco Ruggeri, Yu-Cherng Chang, Florence Cabot, Arthur Ho, Sonia Yoo, Jean-Marie Parel, and Fabrice Manns, "Objective dynamic changes in lens curvature during accommodation using optical coherence tomography images (Conference Presentation)," Proc. SPIE 10474, Ophthalmic Technologies XXVIII, 1047419 (Presented at SPIE BiOS: January 28, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2295005.5751463173001.
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