Biometry A Scan

The refractive power of the human eye depends on three factors: the power of the cornea, the power of the lens, and the length of the eye. Following cataract surgery, only the power of the cornea and the length of the eye are relevant. If both of these variables are known, it is possible to calculate what lens power will give the best refraction. Biometry is the process of measuring the power of the cornea (keratometry) and the length of the eye, and using this data to determine the ideal intraocular lens power.

Biometry (A-scan) is used to determine eye length for calculation of IOL power. Briefly, the total refractive power of the emmetropic eye is approximately 60. Of this power, the cornea provides roughly 40 diopters, and the crystalline lens 20 diopters. When a cataract is removed, the lens is replaced by an artificial lens implant. By measuring both the length of the eye (A-scan) and the power of the cornea (keratometry), a simple formula is used to calculate the power of the intraocular lens needed. At smile laser eye centre we perform Biometry Scan at world’s most advanced proven gold standard Nidek Japan US-4000.