What constitutes as a non-invasive test performed by assistants under the supervision of an optometrist?

Pachymetry is considered a non-invasive test that measures the thickness of the cornea and can be performed by trained assistants under the supervision of an optometrist. The procedure involves using a device called a pachymeter, which does not penetrate or disrupt the eye's structure; it simply gauges the thickness of the cornea, providing valuable information for diagnosing various eye conditions.

In California, specific non-invasive tests like pachymetry fall within the scope of procedures that optometrists can delegate to their assistants as they do not involve invasive techniques or complex clinical decision-making. This delegation is permitted because such tests are straightforward and can be safely conducted by trained personnel without compromising patient safety.

The other options listed involve more invasive procedures or actions that require a higher level of clinical judgment, thus placing them outside the scope of what can be performed by assistants. Eye surgery, for example, is an invasive procedure that requires a licensed practitioner to perform. Prescription writing also requires a licensed optometrist's authority, as it involves clinical judgment based on a patient’s health status. Vision therapy, while non-invasive in nature, involves complex procedures and ongoing treatment plans, which are also beyond the scope suitable for assistants without direct supervision.