What is it about?
Our research explores how the constant, rhythmic fluctuations in eye fluid pressure—driven by the human cardiac cycle—affect the delicate tissues at the back of the eye. We built a 3-D computer model of the human eye to simulate how the lamina cribrosa, a mesh-like structure within the optic nerve head, stretches and deforms with each heartbeat. By testing both normal and elevated fluid pressures, we discovered that the physical strain on these tissues increases under pathological conditions similar to primary open-angle glaucoma. Our finite element analysis revealed that the peak maximum principal strains in the lamina cribrosa ranged from 0.7% to 1.4%, with the most significant stretching occurring along the outer edges of the tissue.
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Why is it important?
Historically, clinical measurements of eye pressure have been treated as static numbers, which fails to capture the dynamic, potentially damaging fluctuations that occur second by second. Our work is unique because it models the structural biomechanical response of the optic nerve head to the combined, continuous loading of both changing intraocular pressure and cerebrospinal fluid pressure. This introduces the critical concept of mechanical fatigue to glaucoma research. While a single heartbeat does not cause immediate structural failure, the repetitive physical strain over millions of cardiac cycles could accumulate and degrade the optic nerve tissues over time. Understanding this mechanism paves the way for new cumulative damage models that factor in natural aging, offering fresh perspectives on how irreversible blindness develops.
Perspectives
Developing the finite element models for this project was an immensely rewarding engineering challenge for me. Working closely with my colleagues from the Mechanical and Aerospace Engineering Department at NC State and the Department of Ophthalmology at UNC Chapel Hill allowed us to effectively bridge the gap between advanced computational mechanics and practical clinical ophthalmology. I am particularly excited about how our theoretical simulations in this study can directly inform and inspire future physical experiments. By demonstrating that cyclical mechanical strain likely contributes to long-term tissue fatigue, I hope our findings motivate the design of new in vitro studies to observe exactly how mechanosensitive cells react to these relentless, microscopic pressure changes.
Andrey V Kuznetsov
North Carolina State University
Read the Original
This page is a summary of: A finite element model investigating the cyclic strains in the lamina cribrosa and their potential role in glaucoma, Modeling and Artificial Intelligence in Ophthalmology, June 2022, Kugler Publications,
DOI: 10.35119/maio.v4i1.118.
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