Investigating the action of the 193-nm and 223-nm radiation of excimer lasers on the cornea of the human eye in refractive surgery

Abstract

This paper presents a study of the optical properties of the components of the stroma of the human cornea in the wavelength range 190–250nm. It is shown that absorption of 223‐nm radiation by the corneal fluid is a factor of 20 less than of 193‐nm radiation. Because of this effect, the rate and efficiency of ablation of the cornea is about a factor 2 greater for laser radiation with a wavelength of 223nm than for 193‐nm radiation. The temperature on the surface of the cornea has been measured when radiation with wavelengths 193 and 223nm is acting on it. It was found that the relative temperature increase on the surface of the cornea during ablation by wavelength 193nm was 11°C, and during ablation at 223nm only 5°C for identical parameters of operation and laser radiation. It is shown that 223‐nm radiation is preferable for performing refractive operations, as having a number of advantages over the traditionally used 193‐nm radiation.