<prompt> The wavelength of the excimer laser used for corneal refractive surgery is190nm191 nm193 nm195 nm  <response>: All clinical excimer lasers use are argon-fluorine ArF gas. The wavelength is in the UV region 193 nm, which has been determined to be safe for human ocular use.Therapeutic applications of excimer lasers are: photorefractive keratectomy PRK, laser-assisted in-situ keratomileusis LASIK for correction of refractive errors and phototherapeutic keratectomy PTK for corneal diseases such as band-shaped keratopathyRef: Khurana; 4th ed; Page no: 431 