What is corneal pachymetry?
The corneal pachymetry is an examination that measures the thickness of the cornea . Knowledge of corneal thickness is used to define the reliability of measurement of eye pressure. The examination is also carried as a tool for evaluating some pathologies of the cornea, such as keratoconus, the corneal edema and in diagnosing glaucoma.
There are different techniques of investigation: tomography corneal scheimpflug room (optical pachymetry) provides a map of the corneal pachymetry or an ultrasound probe (pachymetry acoustics). In the first case you can have a map that shows corneal pachymetry thickness at every point and allows you to identify the location and value of the thinnest point.
What is the purpose of corneal pachymetry?
The test serves to measure the thickness of the cornea, the first natural lens that the light encounters in its path inside the eye.
Preparation standards
There are no specific rules of preparation. For the examination performed with pachymetry, ultrasound is need. Before the examination, aesthetic eye drops are applied to the eyes for a few moments using a probe similar to a small pen. For the pachymetry procedure, aesthetic eye drops are optional (see acquisition process corneal tomography).
Which patients can undergo the exam?
The examination may be performed by patients of all ages, including children, who are able to guarantee an acceptable collaboration in order to ensure a reliable result of the examination. It is used in particular in all subjects known or at risk for glaucoma in patients with corneal diseases and in those who must undergo surgery with corneal cross-linking, corneal transplant or refractive surgery.
Is the exam painful or dangerous?
In the case of the pachymetry ultrasonic (after applying anaesthetic to the eye), it is not a painful examination to be performed, as it is to be carried out. The anaesthetic is used to avoid the feeling of pain and discomfort while we are touching the corneal surface with a small probe. In the case of the pachymetry optical examination, it is a non-invasive examination as there is no contact with the ocular surface.
How is the exam performed?
The patient is made to sit on a stool or chair for the acquisition during the pachymetry ultrasonic examination. Anaesthetic is instilled into the eye and the doctor rests a probe on the corneal surface to detect corneal thickness. The measurement can be repeated at various points of the corneal surface, if necessary. When the exam begins the patient’s eyes capture a light source continuously for a few seconds during which the instrument performs a series of scans of the cornea. A dedicated computer performs the morphological and morphometric analysis, extracts the value of the pachymetry detected in several points of the corneal surface and the minimum value of the corneal thickness is detected.
