Certified Paraoptometric (CPO) Practice Exam 2025 – All-in-One Study Guide to Ensure Exam Success!

Before measuring intraocular pressure (IOP) with a Tonopen, it is essential to anaesthetise the patient's eyes. This is because the process of measuring IOP can cause discomfort, and topical anaesthesia helps ensure that the patient does not experience pain or significant discomfort during the measurement. By numbing the surface of the eye, the clinician can obtain a more accurate reading, as the patient is less likely to blink or otherwise react to the stimulation caused by the Tonopen.

Dilating the pupil is not necessary for IOP measurement with a Tonopen. This procedure focuses on pressure assessment rather than the internal structures of the eye that dilation would normally facilitate examination of. Applying a warm compress does not have a relevant role in this context, as it is generally used for other therapeutic purposes rather than for performing IOP measurements. Similarly, administering a sedative is not required because the procedure can typically be performed comfortably with just topical anaesthesia, with most patients able to remain alert and calm.