Corneal stress influenced by thickness in normal eyes, curvature in keratoconic eyes
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DENVER — Corneal stress distribution is driven by thickness in normal eyes but is influenced more by curvature in eyes with keratoconus, according to a presenter here.
“The common belief is that stress is really influenced in all eyes, especially keratoconus eyes, by thickness,” Kayla M. Knoll, MS, told Healio/OSN at the Association for Research in Vision and Ophthalmology meeting. “We took the traditional hoop stress formula, which takes pressure into account, and removed the pressure in order to isolate the corneal contribution to stress.”
Knoll and colleagues used pachymetry and anterior tangential curvature maps collected in 310 normal eyes and 66 eyes with keratoconus and a modified hoop stress formula to create an average stress map between the two groups of eyes.
“What we noticed is that the lowest stress in keratoconus eyes was associated with high curvature and with low pachymetry, which when we look at our hoop stress formula means the low stress is driven more so by curvature rather than thickness,” Knoll said.
The researchers also examined zone of maximum curvature, a 2-mm zone of curvature on both maps, and found that the zone of maximum curvature was significantly associated with changes in corneal contribution to stress, Knoll said.
“We’re hoping it could be potentially a really good predictor of the biomechanical progression in keratoconus and maybe, down the line, help with detecting that at an earlier stage,” she said.
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Knoll KM, et al. Comparison of stress distribution patterns in keratoconus and healthy eyes. Presented at: Association for Research in Vision and Ophthalmology meeting; May 1-4, 2022; Denver.
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