Keratometry is a process which is used to measure the curvature of the cornea. It is performed by an eye specialist such as an ophthalmologist, using a device known as a keratometer or ophthalmometer. No special preparation is required on the part of the patient for a keratometry session, and the procedure is usually painless, unless a patient experiences difficulty sitting still. The basic keratometer was developed in 1880, although the design has been refined significantly since.
In a keratometry procedure, a device is used to measure the degree of curvature in the cornea, looking for the shallowest and steepest curves. Most modern keratometers utilize computers and optical sensors, rather than forcing the doctor to make calculations, and the computer can compare the patient's cornea with a database of known measurements and typical norms. Ultimately, numbers will be produced so that the keratometry data can be recorded in the patient's chart or passed on to other physicians.
One of the main reasons to perform keratometry is to check a patient's astigmatism, a vision problem caused by irregularities in the shape and curvature of the cornea, and to determine the degree of the astigmatism. With the numbers from the keratometer, the doctor can determine which options are available to correct the astigmatism so that the patient can see more clearly. The device can also be used to look for irregularities in corneal shape between the eyes.
Prior to certain types of eye surgery, the surgeon may request keratometry to get a complete picture of the eye, and the measurements may also be used to guide the procedure. It is also common to have sessions with a keratometer after eye surgery so that the results of the surgery can be followed, and the eye can be monitored for changes. Identifying unexpected changes in the eye early is critical, as it can mean that an emerging issue is spotted quickly.
As with prescriptions for corrective lenses, patients can take their keratometry readings with them if they want to receive care from another doctor. Patients can also request copies of their charts, something which patients may want to do if they have complex eye problems and they are relocating to another area. Having a copy of the chart on hand can save a new eye doctor time, and ensure that the patient receives the most appropriate care and treatment from the first vision appointment.