A-scan biometry measures the distance between which internal structures of the eye?

A-scan biometry is an important diagnostic tool used in ophthalmology to measure distances between internal structures of the eye, specifically focusing on the anterior and posterior segments. It primarily measures the distance from the anterior surface of the cornea to the internal structures, including the lens and the retina. This technique is crucial for calculating the appropriate intraocular lens power for cataract surgery, as an accurate understanding of these distances helps ensure optimal vision post-operatively.

Measuring the distance between internal ocular surfaces provides the necessary data that helps in the assessment of eye geometry and refractive status. This information is vital for various procedures, including cataract surgery and the evaluation of conditions like myopia and hyperopia. Compared to the other options, which focus on specific structures or are less applicable to the overall purpose of A-scan biometry, the measurement of internal ocular surfaces is the broadest and most relevant to the functionality of A-scan technology.