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General Practice 2023

Topography of córnea (keratoscopy): what é and what is it for

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Topography of córnea (keratoscopy): what é and what is it for
Topography of córnea (keratoscopy): what é and what is it for

Keratoscopy, also called corneal topography or corneal topography, is an ophthalmological exam widely used in the diagnosis of keratoconus, which is a degenerative disease characterized by deformation of the cornea, which ends up acquiring a cone shape, with difficulty seeing and greater sensitivity to light.

This exam is simple, performed in the ophthalmological office and consists of mapping the cornea, which is the transparent tissue that is in front of the eye, identifying any change in this structure. The result of the corneal topography can be indicated by the doctor right after the exam.

Although it is mostly used in the diagnosis of keratoconus, keratoscopy is also widely performed in the pre and post-operative period of ophthalmic surgeries, indicating whether the person is able to perform the procedure and if the procedure had the expected result.

What is it for

Corneal topography is performed to identify changes in the corneal surface, being performed mainly for:

  • Measure the thickness and curvature of the cornea;
  • Diagnosis of keratoconus;
  • Identification of astigmatism and myopia;
  • Evaluate the adaptation of the eye to the contact lens;
  • Check for corneal degeneration.

In addition, keratoscopy is a procedure that is often performed in the preoperative period of refractive surgeries, which are surgeries that aim to correct the change in the passage of light, however not all people who have a change in the cornea are able to perform the procedure, as is the case of people with keratoconus, because due to the shape of the cornea, they are not able to perform this type of surgery.

Therefore, in the case of keratoconus, the ophthalmologist may recommend the use of prescription glasses and specific contact lenses and, depending on the degree of corneal alteration, may indicate the performance of other surgical procedures.Understand how the treatment for keratoconus is done.

Corneal topography can also be performed postoperatively, and it is important to verify whether the change has been corrected and the cause of poor vision after refractive surgery.

How it's made

Keratoscopy is a simple procedure, performed in the ophthalmological office and takes between 5 and 15 minutes. To perform this exam, there is no need for pupil dilation, because it will not be evaluated, and it may be recommended that the person does not wear contact lenses 2 to 7 days before the exam, but this recommendation depends on the doctor's guidance and the type. lens used.

To perform the exam, the person is placed in a device that reflects several concentric rings of light, known as Placido rings. The cornea is the structure of the eye responsible for the entry of light and, therefore, according to the amount of light reflected, it is possible to check the curvature of the cornea and identify changes.

The distance between the reflected rings of light is measured and analyzed by software on a computer that is associated with the equipment. All information obtained from the emission of the light rings is captured by the program and transformed into a color map, which must be interpreted by the doctor. Based on the colors present, the doctor can check for changes:

  • Red and orange are indicative of greater curvature;
  • Blue, violet and green indicate flatter curvatures.

Thus, the more red and orange the map, the greater the change in the cornea, indicating that other tests are necessary to complete the diagnosis and initiate the appropriate treatment.

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