ALLOWABLE ERRORS OF THE AUTOMATED INTRAOPERATIVE BIOMETRY OF APHAKIC EYE

Abstract

Background. Providing planned postoperative emmetropic refraction with an error within ±0.25 diopters for an eye with an implanted intraocular lens (IOL).

Objective. The purpose of the paper is the justification of the permissible errors in the intraoperative biometric of the optical system of the eye, which allows determining the optical power of the IOL with accuracy, ensuring the accuracy of the planned postoperative refraction within ±0.25 diopters.

Methods. The determination of the necessary optical power of the IOL is considered based on the results of intraoperative biometrics of the optical system of the eye at the stage after the phacoemulsification of the pathological lens. The determination method requires accurate measurement of the radius of the corneal surface, the distance from the front surface of the cornea to the retina, and the distance from the front surface of the cornea to the location of the implanted in the eye IOL. The permissible error in determining the optical power of the IOL was established, at which the postoperative refraction of the eye can differ from the planned one by a value of no more than ±0.25 diopters. The research method is mathematical modeling in the environment of the ZEMAX program using Arizona mathematical model of the eye. The requirements for the accuracy of measurements of the mentioned above geometric parameters of the aphakic eye optical system are justified based on the established permissible error in determining the required optical power of the IOL.

Results. It was established that, depending on the location of the IOL in the patient’s eye, the permissible error in determining the required optical power of the IOL for emmetropic postoperative refraction is from ±0.3 to ±0.42 diopters, and for the optical system of the average eye to ±0.337 diopters. It is shown that the permissible error in determining the required optical power of the implanted IOL is assured provided that the geometrical parameters of the aphakic eye are hardware-measured with the same error for all measured parameters within ±0.042 mm.

Conclusions. The research results allow us to determine the accuracy requirements for intraoperative biometry of the aphakic eye, which is necessary to ensure the error of postoperative emmetropic refraction of the eye within ±0.25 diopters.