What is the role of the visual axis in A-scan biometry?

The visual axis plays a crucial role in A-scan biometry by ensuring precise alignment of the ultrasound probe during measurements. A-scan biometry is a diagnostic procedure used to measure the dimensions of the eye, particularly for calculating the required power of intraocular lenses during cataract surgery. The visual axis, which is the line of sight from the object being viewed to the fovea, helps the clinician position the A-scan probe correctly. Proper alignment is vital because any deviation can result in inaccurate measurements of the eye’s anteroposterior length, which is essential for successful surgical outcomes. Thus, the visual axis is integral to the measurement process, directly influencing the accuracy of the data obtained.