With ultrasound or optical biometry, the doctor measures the length of the eyeball, thickness and curvature of the cornea, and the depth of the anterior eye chamber using an ultrasound or a OCT. Based on these data, a biometer calculates in detail the needed intraocular lens for cataract surgery according to different formulas and constants.
Using laser rays, the biometer enables painless and precise measurement of the eyeball length. This technique does not require anesthesia on the cornea as there is no need to place the ultrasound probe onto the eye. The data collected by this method are even more precise compared to ultrasound measurements. On the other hand, ultrasound biometry is a safer method for progressed mature cataract, where a laser often cannot “get through” and take measurements correctly.