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Alex Thanhlong Pham, Ethan Adre, Keke Liu, Yu-Cherng Chang, Ivan Shestopalov, Florence Cabot, Siobhan Williams, Giovanni Gregori, Marco Ruggeri, Arthur Ho, Jean-Marie A Parel, Fabrice Manns; Age- and accommodation- dependence of the human crystalline lens shape and thickness measured with extended-depth Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1244.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the changes in anterior and posterior lens curvature and thickness with accommodation and with age using extended-depth Optical Coherence Tomography (OCT).
Under an IRB protocol, 15 eyes from 10 subjects (Age range: 21 to 60 years) were imaged with an accommodation biometry system that combines a fixation target with adjustable vergence and a custom-built extended-depth OCT system that enables imaging of the anterior segment from the anterior corneal surface to the posterior lens (840 nm, 12,500 A-lines/s, 8 μm axial resolution) (Ruggeri et al, Biomed Opt Exp 2012). For each subject, OCT images (400 A-lines) were acquired with the fixation target adjusted to vergences ranging from 0 D (distance) to 6 D (near) in 1 D increments. Images acquired at each stimulus were processed using a program written in MATLAB to automatically segment the corneal and lens boundaries and correct for refractive distortions. Distortion correction for the posterior surface of the lens assumed a uniform refractive index (n=1.415) for the crystalline lens. For each subject, the change in anterior and posterior lens radius of curvature and lens thickness change with accommodation stimulus was estimated using linear regression to produce shape- and thickness-stimulus slopes (in mm/D). Change in the lens curvature and shape was assessed as a function of age.
Anterior and posterior lens curvatures steepened and lens thickness increased with accommodation, consistent with the Helmholtz theory of accommodation (Figure 1). The accommodative change in shape (in mm/D) decreased with age (Figure 2), unlike results obtained using Scheimpflug imaging (Dubbelman et al, Vis Res 2005).
OCT biometry enables characterization of the age-dependence of the accommodative response of the crystalline lens.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1: Typical accommodative response showing the change in anterior lens curvature, posterior lens curvature, and lens thickness versus accommodation in response to step stimuli of with amplitude ranging from 1D to 6D. Data is from a 26 year old subject.
Figure 2: Age-dependence of the slopes of anterior radius (left), posterior radius (center) and lens thickness (right) versus accommodation stimulus.
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