Which instrument is primarily utilized for measuring intraocular pressure?

The tonometer is the primary instrument used for measuring intraocular pressure (IOP). This measurement is crucial in the diagnosis and management of conditions like glaucoma, where elevated IOP can lead to damage of the optic nerve and vision loss. Tonometers work by applying a small force to the eye and measuring the resistance to that force, which correlates with the pressure within the eye.

In contrast, other instruments serve different purposes: a slit lamp is primarily used for examining the anterior segment of the eye, including the cornea, iris, and lens, providing detailed views of eye structures. An ophthalmoscope is utilized for inspecting the interior of the eye, particularly the retina and optic disc, which is important for detecting various eye conditions but does not measure IOP. A keratometer, on the other hand, is designed to measure the curvature of the cornea, which is important for fitting contact lenses but does not assess intraocular pressure.