What drug is commonly used for applanation tonometry?

The commonly used drug for applanation tonometry is benoxinate. Benoxinate is a topical anesthetic specifically formulated for ocular use, allowing for painless measurement of intraocular pressure during applanation tonometry. Its efficacy in providing local anesthesia ensures that the patient experiences minimal discomfort during the procedure, which is crucial for obtaining an accurate reading of intraocular pressure.

While other anesthetics, such as proparacaine, lidocaine, and tetracaine, can be used in ophthalmic procedures, they are not typically the first choice for applanation tonometry. Proparacaine is another effective anesthetic, but its usage is more common in procedures where short-term anesthesia is sufficient. Lidocaine, while effective as an anesthetic, is not as frequently used in this application as it may not provide the rapid onset that is needed. Tetracaine also serves as an anesthetic but is not preferred in this specific context due to longer duration and potential for toxicity in the ocular environment.

Benoxinate's specific formulation makes it particularly suited for this diagnostic test, which is why it is the standard choice in practice.