The keratometer is an instrument used to measure what?

The keratometer is specifically designed to measure the curvature of the cornea. This instrument assesses how steep or flat the corneal surface is, which is critical for fitting contact lenses accurately, as the curvature of the cornea greatly influences lens design and fit. Understanding the corneal curvature helps eye care professionals determine the appropriate lens type and prescription, ensuring that the lenses provide optimal vision correction and comfort.

In contrast, intraocular pressure is measured with a tonometer, and lens power is determined using a lensometer for prescription glasses or contact lenses. Pupil diameter might be assessed using a pupillometer or a ruler but is not the function of a keratometer. Thus, the primary role of the keratometer in ophthalmic practice is to provide precise measurements of corneal curvature.