Finite element models of scleral creep in form-deprivation myopia

摘要

The deformational characteristics of the myopic scleral globe support the hypothesis that myopia (nearsighted-ness) progresses through abnormal axial stretching of the sclera (Curtin, 1985). Phillips and McBrien (1995) demonstrated with finiteelement (FE) models that elastic expansion, alone, could not account for abnormal axial expansion in deprivation myopia. Siegwart and Norton (1994) found that myopic sclera displayed greater creep rates than paired controls, suggesting that creep mayplay a significant role in myopic elongation. To our knowledge no previous FE modeling studies have included scleral viscoelasticity.In the present study, FE models of scleral globes were developed that contained creep properties obtained from tree shrews subject to monocular form-deprivation. Model predicted axial elongations resulting from a realistic intraocular pressure werecompared with measured values to determine whether creep could account for excessive myopic elongations. Creep properties were reduced anteriorly in some models and predicted elongations were further compared to measured elongations.