Limbus Compensation for corneal deformation Under Intraocular Pressure Fluctuations

Abstract Purpose A stable corneal refractive power (RP) is essential for clear vision, yet the mechanism by which the limbus modulates shape under intra-ocular-pressure (IOP) fluctuations remains uncertain. Previous qualitative studies suggested a “buffer” role, but lacked quantitative optical evidence. This study aims to quantify the limbus’s effect on refractive stability. Methods A three-dimensional finite-element model of the human cornea was built with a Holzapfel-Gasser-Ogden formulation and spatially varying collagen. After validation against ex-vivo inflation tests, both anterior and posterior curvatures were tracked to compute true refractive power. Limbus width (0–3 mm) and IOP (0–50 mmHg) were systematically varied to evaluate their coupled influence on refractive power. Results The model reproduced the central displacement–pressure curve (R² = 0.99) and showed that > 70% of strain concentrates in the limbal ring. RP first increased then decreased with greater limbal width, achieving maximal stability at 1–2 mm. Within the physiological IOP range (10–20 mmHg) this width restricted RP variation to ± 0.20 D, while narrower or wider rims allowed up to ± 0.63 D. Using anterior-surface-only optics introduced > 1 D error under high pressure, underscoring the need for dual-surface calculations. Conclusion The limbus acts as an elastic strain absorber that isolates the central cornea from IOP-induced deformation. A 1–2 mm limbal width minimizes refractive power oscillations, a value that coincides with typical human anatomy. These findings quantitatively substantiate the biomechanical importance of the limbus and offer design guidelines for limbal-sparing surgical procedures and bio-engineered corneal implants. Clinical trial number: not applicable.