What does a non-contact tonometer (NCT) measure?

A non-contact tonometer (NCT) is specifically designed to measure intraocular pressure (IOP), which is a critical aspect in the screening and management of glaucoma and other eye conditions. During the procedure, a puff of air is directed at the cornea without any physical contact, and the instrument gauges the amount of deformation of the cornea to determine the pressure within the eye. This method is quick, non-invasive, and generally well-tolerated by patients, making it a commonly used tool in optometry practices.

In contrast, the other options represent different measurements related to eye health but do not pertain to what a non-contact tonometer assesses. For example, corneal curvature is typically measured using a keratometer or topographer, visual acuity is assessed with an eye chart, and pupil dilation is evaluated with a light source or through observation of the pupil's response to light stimuli. Therefore, the primary function of a non-contact tonometer is indeed to measure intraocular pressure.