Biomechanical effect of segmental scleral buckling surgery

Purpose: The current paper studies the mechanical effect of segmental buckling surgery for treatment of retinal detachment using the finite element (FE) method. The effects of different eye sizes, intraocular pressures, and silicon sponge size and locations are examined. Indicative study on the visual optics from the emmetropia to the myopia by the surgery is also carried out. Ophthalmologists may have an advanced understanding of the possible surgical outcomes from the current study in order to plan better patient-specific surgical procedure. Methods: The solid tissues in the 3D FE model are modeled by eight-node hexagonal solid elements using a Lagrangian mesh. The inner vitreous and aqueous liquids are modeled by a Eulerian mesh. The eye tissues are treated as hyperelastic solids, and the liquids are represented with linear polynomial equations of state. Results: The segmental scleral buckling procedure induces stress concentrations in the suture region, which may lead to bleeding. A smaller eye sustains relatively higher stress, thus has a greater chance to bleed. Smaller silicon implant leads to much higher stress, and the effect of the relative posterior and anterior positions of the silicon sponge is inconsistent. The surgery causes or aggravates myopia due to the average corneal curvature increase, although the optical length of the eye is reduced at high indentations. Exceptions are eyes with very large or small intraocular pressure at moderate indentation. Eyes with small intraocular pressure may sustain more severe refractive error by the surgery. Astigmatism may be caused or aggravated by the irregular deformation of the cornea and the deflection of the crystalline lens.