Certified Ophthalmic Assistant Practice Exam

A tonometry technique that displaces a minimal amount of fluid is

1. Goldmann

2. Non-contact

3. Rebound

4. Applanation

The correct answer is: Rebound

The correct choice of applanation tonometry reflects its unique principle of measuring intraocular pressure (IOP) by flattening a specific area of the cornea. This technique involves displacing only a minimal volume of fluid, allowing for an accurate assessment of IOP while minimizing discomfort for the patient. The method is based on the indentation of the cornea and is effective due to its ability to provide reliable readings by taking into consideration the corneal thickness and curvature. In contrast, the other tonometry techniques have different mechanisms. Goldmann tonometry, although also an applanation method, often involves a larger volume of fluid displacement compared to the minimal approach mentioned in the question. Non-contact tonometry uses a puff of air to measure IOP, which can cause more significant displacement and pressure fluctuations. Rebound tonometry utilizes a small, plunger-like device that makes brief contact with the cornea, but it may also involve a different fluid displacement dynamic than the targeted minimal aspect highlighted in the question. Hence, applanation tonometry stands out for its precise control over fluid displacement.