Certified Ophthalmic Technician (COT) Practice Test 2026 - Free COT Practice Questions and Study Guide

Immersion A-scan biometry is recognized for its enhanced accuracy primarily because it minimizes the effects of corneal compression. In this method, the ultrasound probe is immersed in a water-filled container that encompasses the eye, allowing for a better acoustic coupling. This immersion technique reduces the pressure exerted on the cornea, which is a significant factor when measuring eye dimensions.

Less corneal compression leads to a more accurate representation of the axial length of the eye since any indentation can alter the measurements taken during the procedure. This precision is particularly crucial for calculating appropriate intraocular lens (IOL) power in cataract surgery.

While contact A-scan and other forms of biometry, such as optical coherence tomography and ultrasound biometry, have their benefits, they are generally more susceptible to issues related to corneal pressure. In those methods, the probe directly contacts the cornea, which can lead to inaccuracies in measurement due to potential flattening or deformation of the corneal surface. Therefore, immersion A-scan is preferred for its ability to provide reliable measurements with minimal influence from external forces acting on the eye.