Keratometry: Devices and principles. Literature review

Accurate preoperative determination of biometric parameters of the eye is the key to successful lens surgery, achieving high and predictable functional results. At the preoperative stage of refractive and cataract surgery, special attention is paid to the study of corneal parameters, in particular, optical power – keratometry. Corneal power is one of the important parameters in calculating intraocular lens power, in the selection of patients for surgery, the diagnosis of corneal diseases, monitoring the dynamics of pathological processes in the cornea, and analyzing postoperative results. Keratometry is based on the fact that the anterior surface of the cornea has mirror properties, and the size of the image reflected from it depends on the curvature of the cornea, which indicates the possibility of calculating its refractive power based on the analysis of the displayed image size. However, the methods and principles of keratometry are diverse. In this review, an analysis of literature devoted to the study of methods for determining the optical power of the cornea is carried out in order to systematize the data. The review highlights the historical aspects of keratometry – from the first attempts to measure the radius of the anterior surface of the cornea to the first ophthalmometer, shows the evolution of ophthalmometry technology – from manual keratometry to keratotopography and keratotomography, separately reflects the principles and formulas for calculating the optical strength of the cornea.