Pachymetry is a diagnostic procedure that measures corneal thickness. It is vitally important when the doctor suspects the patient suffers from glaucoma or keratoconus. The thickness of the cornea also determines other parameters in the eye, such as eye pressure. Precisely measured corneal thickness is a parameter for the preparation of different surgical interventions.
Among other functions, the cornea has the task to enable the refraction of the light rays with its curvature. If the corneal thickness or its curvature changes, these alterations can have a significant influence on visual acuity. Pachymetry enables precise measurement of the corneal thickness and thus helps the ophthalmologist to diagnose different diseases. By measurement in due time, different diseases can be stopped, such as keratoconus or glaucoma.
Eye pressure gives a specific form to the eye, which is important for the eye to function normally. Blood pressure disorder can be a symptom of glaucoma. If not treated on time, it can cause blindness. Corneal thickness influences the result of the measurement of eye pressure. An average corneal thickness in the center is between 490 and 560 micrometers. With an increased corneal thickness, values can be falsely higher, and with decreased thickness – falsely low values. For this reason, the value of corneal thickness is necessary to establish real values of the eye pressure.
Since different refractive disorders can be corrected with a laser procedure, the exact thickness of cornea determines if the laser intervention is recommendable and what type of intervention to choose. With Corneal Crosslinking, it is also necessary to measure the corneal thickness. In the case of significant corneal thinning, one type of corneal transplant is recommendable (DALK).
Pachymetry is painless. Corneal thickness can be measured by ultrasound or optical pachymetry – computerized corneal tomography (Scheimpfug) or with OCT. Ultrasound measurement is a contact method, where the eye is first anesthetized with drops to decrease the irritation, and then a small ultrasound probe is gently placed onto the cornea. On the other hand, tomography and OCT do not require anesthetic because there is no contact with the eye during measurement.
Most often it is enough to do one measurement, but in some cases, it can be repeated when it is necessary to follow some conditions (corneal edema) or if the doctor suspects there is a specific disorder.