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Measurement of Lens Curvature Change During Accommodation With High–Speed Optical Coherence Tomography

¹ Dept of Biomedical Engineering, Case Western Reserve Univ, Cleveland, OH
² Dept of Ophthalmology, Federal University of Sao Paulo, Sao Paulo, Brazil
³ Doheny Eye Institute, Univ of Southern California, Los Angeles, CA

Commercial Relationships: Y. Li, Carl Zeiss Meditec R; M.R. Chalita, None; D. Huang, Carl Zeiss Meditec F, P.

Support: NIH EY13015 and Carl Zeiss Meditec, Inc.

Abstract

Purpose: To use a high–speed corneal and anterior segment optical coherence tomography (CAS–OCT) system to measure crystalline lens curvature change during accommodation.

Methods: A high–speed (2000 a–scan/sec) 1.3–micron wavelength CAS–OCT system (17 micron FWHM axial resolution in tissue) was used. The anterior chamber (AC) and the lens were imaged in both eyes of a 39 years old subject. The internal fixation target was viewed through incrementally varied add power (+1 to –6 D) to control accommodation. OCT was repeated after instillation of phenylephrine 2.5% and then tropicamide 1%. Anterior and posterior lens curvatures were measured in terms of radius of curvatures in the central D=3mm zone. A larger analytic zone (D=6mm) was also used with the dilated eyes to detect the difference in central/periphery anterior lens curvature changes.

Results: The radius of curvature of anterior lens decreased with accommodation in the dry state (OD 0.69mm/D, OS 0.56mm/D) and after phenylephrine (OD 0.45mm/D, OS 0.4mm/D). The radius of curvature of posterior lens also decreased with accommodation both without drops (OD 0.069mm/D, OS 0.079mm/D) and after phenylephrine (OD 0.08mm/D, OS 0.11mm/D). The anterior radius of curvature decreased less in the periphery (OD 0.4mm/D, OS 0.34mm/D) in the dilated eyes. All slopes of regression lines presented above were significantly different from zero with p < 0.03–0.001. No significant accommodative response was detected after Tropicamide.

Conclusions: Both anterior and posterior lens surface become more curved with accommodation, but the anterior surface change is larger. The central part of the lens steeps more than the periphery lens. OCT provided direct and quantitative measurement of lens curvature changes during the accommodation. This non–contact imaging method may be useful for the development and validation of presbyopia therapies.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical

© 2005, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. For permission to reproduce any part of this abstract, contact the ARVO Office at arvo{at}arvo.org.