Original article
Stiffness of Retinal and Choroidal Tissue: A Surface Wrinkling Analysis of Epiretinal Membranes and Choroidal Folds

https://doi.org/10.1016/j.ajo.2006.04.019Get rights and content

Purpose

To measure the wrinkling periodicity (peak-to-peak or trough-to-trough distance) for epiretinal membranes and contraction-induced choroidal folds, and use this data to infer differences in the elastic properties of the retina and choroid, respectively.

Design

Retrospective case review.

Methods

Forty eyes were identified with epiretinal membranes (33 eyes) or contraction-induced choroidal folds (seven eyes). Digital red-free photographs were used to determine the average peak-to-peak distance between adjacent folds of retina or choroid using commercially available software.

Results

The average peak-to-peak spacing was considerably larger for contraction-induced choroidal folds vs retinal folds caused by epiretinal membranes (278.2 ± 62.2 vs 82.2 ± 7.66 μm, respectively; P = .0001). There was no statistically significant correlation between the peak-to-peak distance and patient age for the epiretinal membrane group (P = .25) or the choroidal folds group, although the age range of patients within the later group was narrow.

Conclusions

Epiretinal membranes and contraction-induced choroidal folds are two examples of wrinkling of biologic tissue under tangential stress. The larger peak-to-peak spacing for choroidal folds vs retinal folds demonstrates that the choroid is considerably stiffer than the retina under mechanical deformations.

Section snippets

Methods

In this retrospective study, 33 eyes of 28 patients between 16 and 81 years old with epiretinal membranes and seven eyes of seven patients between 52 and 88 years old with contraction-induced choroidal folds were included. This small retrospective study was exempt from Institutional Review Board approval as data collection was done before implementation of the Health Insurance Portability and Accountability Act (HIPAA) privacy rules; in subsequent analysis, no patient was identified

Mathematical model of retinal and choroidal folds

The mathematical analysis of the wrinkling behavior of contraction-induced choroidal folds and epiretinal membranes is based upon recent advances on understanding the geometry and physics of wrinkling. Herein, wrinkling refers to the periodic deformation of large, thin, flat sheets of tissue, wherein the thickness of the tissue sheet is much smaller that the length and width (t ≪ L, W; see Figure 1). Cerda and Mahadevan have shown that such sheets wrinkle in a predictable pattern under

Discussion

Epiretinal membranes and contraction-induced choroidal folds are both examples of sheer-induced wrinkling of biologic tissue under tangential stress. In principle, the wrinkling pattern of such thin tissue sheets is governed by physical principles that reflect the properties of the underlying biologic tissue.1 In this study, I demonstrated that the wrinkling of the neural retina observed in patients with epiretinal membranes causes a regular and predictable wrinkling pattern with little

Lucian V. Del Priore, MD, PhD, received his PhD in Physics from Cornell University and MD with Distinction in Research from the University of Rochester. Dr Del Priore completed Ophthalmology residency, a glaucoma fellowship, and vitreoretinal surgery fellowship at the Wilmer Eye Institute, and is currently the Robert L. Burch Scholar and a Professor in the Department of Ophthalmology at Columbia University in New York.

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  • Cited by (13)

    • Three-Dimensional Spectral-Domain Optical Coherence Tomography Images of the Retina in the Presence of Epiretinal Membranes

      2008, American Journal of Ophthalmology
      Citation Excerpt :

      The geometry of retinal wrinkling is connected to the mechanical properties of the retina. Del Priore recently analyzed this relationship using red-free photographs to measure peak-to-peak distance of folds created by ERMs.18 The detailed description of the retinal surface generated by our approach may lead to a better understanding of the retinal response to mechanical stresses.

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    Lucian V. Del Priore, MD, PhD, received his PhD in Physics from Cornell University and MD with Distinction in Research from the University of Rochester. Dr Del Priore completed Ophthalmology residency, a glaucoma fellowship, and vitreoretinal surgery fellowship at the Wilmer Eye Institute, and is currently the Robert L. Burch Scholar and a Professor in the Department of Ophthalmology at Columbia University in New York.

    Supported in part by the Eye Surgery Fund, Robert L. Burch III Fund, the Macula Foundation, the Hickey Foundation, and Research to Prevent Blindness, Inc, New York, New York.

    View full text