[The effect of intraocular pressure on refractive power of the cornea and the human eye, based on the Liou-Brennan model eye].

INTRODUCTION

It is a clinical experience that with significantly higher intraocular pressure, glass ordering may be inaccurate, therefore, it should be performed after adjustment of intraocular pressure.

OBJECTIVE

To analyze the effect of intraocular pressure on the refractive power of the cornea and of the eye, using geometrical properties of the Liou-Brennan model eye and finite element modeling.

METHODS

Using corneal parameters of the Liou-Brennan model eye, a parametric geometrical model and with these data finite element modelling, using the Ansys (Ansys, Canonsburg, PA, USA) program, has been performed. Corneal tissue properties have been defined based on trilinear material model of Wollensak and boundary conditions based on Pandolfi. The effect of changes in intraocular pressure on geometrical corneal properties with optical impact (corneal curvature at the anterior and posterior corneal surface at the optical center and axial displacement of the anterior and posterior corneal surface points at the optical center) have been analyzed. Based on the geometric characteristics obtained, using the paraxial ray tracing method, changes in the optical properties of the cornea and the eye have been calculated.

RESULTS

With increasing intraocular pressure load, anterior and posterior central corneal radius of curvature decreased and corneal surface points at the optical center at the anterior and posterior surface moved forwards, the cornea thinned. Axial displacement of corneal volume points was maximal for all pressure load values at the optical center of the posterior corneal surface. The refractive power of the cornea decreased as eye pressure increased, while the refractive power of the entire eye increased.

CONCLUSION

We verified using the Liou-Brennan model eye and finite element modelling that a change of the intraocular pressure load between 10 and 30 mmHg may result in 0.31-0.86 mm decrease of the corneal radius of curvature, in 1.5-4.8 D increase in the keratometric values and in about 1.2-3.9 D increase in the total optical power of the eye. A decrease of 0.14 D to 0.69 D has been measured in the corneal optical power in the examined eye pressure range. Orv Hetil. 2022; 163(47): 1872-1879.