Equatorial wrinkles in the human lens capsule

Abstract

Equatorial wrinkles, or crenations, have been previously observed around the equator in coronal images of the human ocular lens. However, wrinkles are typically not apparent when the lens is viewed from saggital directions. In the current paper, the existence and geometry of these wrinkles is shown to be consistent with a mechanical model of the isolated lens, in which the capsule is held in a state of residual tension by a spatially uniform internal pressure. The occurrence of equatorial wrinkles is therefore seen to be a mechanical consequence of the spheroidal shape of the lens capsule and an excess intralenticular pressure. New observations are made, on post mortem lenses, on the geometric arrangement of these equatorial wrinkles. These observations indicate a well-defined pattern in which wrinkles exists along meridional lines in the equatorial regions of the lens. A preliminary 'puncture test' is used to demonstrate that the residual stresses within the capsule in the equatorial region of the lens are broadly consistent with the proposed mechanical model of the lens capsule. It is suggested that the presence of equatorial wrinkles may have an influence on the mechanical performance of the capsule during the accommodation process.

The Development, Growth, and Regeneration of the Crystalline Lens: A Review

“…127 and anisotropic strains have been found to exist in the intact human lens capsule near the equator, coinciding with the GZ. 128 It has also been observed that PCO can be inhibited in vitro by using pharmaceutical agents targeting the cytoskeleton. 129 The cytoskeleton is typically involved in transducing external mechanical cues.…”

Lens Stretching Modulates Lens Epithelial Cell Proliferation via YAP Regulation

“…21 Such anisotropic strains have been found to exist in the intact human lens capsule near the equator, coinciding with the region in which proliferation is known to occur in the mouse lens. 3,22 PCO can be inhibited in vitro by using pharmaceutical agents targeting the cytoskeleton 23 ; the cytoskeleton is known to convey information about mechanical stresses on a cell to the nucleus resulting in changes in protein expression. 24 Together, these results suggest that LECs are strain-responsive cells (i.e., they can alter their behavior in response to mechanical cues from their environment).…”

Orbital fat swelling: A biomechanical theory and supporting model for spaceflight-associated neuro-ocular syndrome (SANS)

“…Choroidal folding presumably results from a loss of tension in the direction perpendicular to wrinkling. This is a geometric phenomenon and would therefore be driven by globe flattening: as the principal radii of curvature change, tension in an inflated membrane (e.g., the choroid) can be lost ( Burd et al, 2017 ). Once tension is removed, these folds may be permanent ( Cassidy and Sanders, 1999 ).…”