The Zonules Selectively Alter the Shape of the Lens During Accommodation Based on the Location of Their Anchorage Points

Abstract

While either the anterior or posterior zonules alone are capable of changing the shape of both lens surfaces, the anterior zonules have a greater effect on the anterior lens surface, and the posterior zonules have a greater effect on the posterior lens surface.

Measurement of Crystalline Lens Volume During Accommodation in a Lens Stretcher

“…The dissection and mounting procedure has been described in detail elsewhere. [18][19][20][21] In summary, eight attachments (shoes) fitting the scleral curvature of the test eye are bonded to the globe. The posterior pole, cornea, and iris are then removed, and full-thickness incisions are made in the sclera between the shoes to produce eight segments for stretching.…”

“…The lens stretcher was programmed to move the stretching arms outward in 0.25-mm steps, up to 2.0 or 2.5 mm of stretching, to simulate disaccommodation. [18][19][20][21][22] The lens stretcher provides measurements of the stretching force at each step. Lens power was measured by finding the focus of a ring-shaped beam with a ray height of 1.5 mm from the lens center using an optical system based on the Scheiner principle.…”

“…Lens power was measured by finding the focus of a ring-shaped beam with a ray height of 1.5 mm from the lens center using an optical system based on the Scheiner principle. [19][20][21] The lens shape was obtained from crosssectional images acquired with a custom-built time-domain OCT system. A detailed description of the system and imaging protocol have been published previously.…”

“…A detailed description of the system and imaging protocol have been published previously. 19,21,23 Images were recorded with 5000 points per A-line at a rate of 20 A-lines per second, with 500 A-lines per B-scan and a total lateral scan length of 10 mm. The axial resolution of the system, defined as the full-width half-maximum of the measured axial pointspread function was 12 lm in air (corresponding to 8 lm in tissue).…”

“…had been subjected to lens-stretching experiments in our second-generation custom-built lens stretcher (EVAS II). 18,19 All eyes were from different animals (i.e., there were no paired eyes). The eyes were selected by excluding tissues with any detectable rotational asymmetry in stretching, any lateral shift of the lens, or insufficient stretching force.…”