Corneal topography provides doctors or ophthalmologists with the most detailed possible information about the curvature of the cornea (the transparent part in the front of the eye), potential eyesight issues, and eye diseases.
- The greatest advantage of corneal topography is its ability to detect conditions that cannot be identified using most conventional testing.
- Identification of deep or superficial corneal disorders/distortions causing visual disturbances and impairment, such as keratoconus (a disorder in which there is progressive thinning of the cornea making it bulge outwards like a cone resulting in blurry vision, double vision, and nearsightedness).
- Contact lens fitting and complex contact lens prescriptions.
- If a patient is to undergo refractive surgery with an excimer laser. In refractive surgery, the corneal topography is an exam of primary importance before and after the surgery.
- In ocular surface disorders, such as pterygium (pinkish, triangular tissue growth on the cornea), corneal topography is used to monitor progression.
- Dry eye evaluation
- Corneal transplants
- Corneal scars or opacities
- Irregular astigmatism (error in the shape of the cornea) following corneal transplantation
- Postoperative cataract extraction with acquired astigmatism
- In patients who may be interested in Ortho K (overnight wear) lenses
What is a cornea?
The cornea is the transparent dome-shaped covering the front of the eye and protecting the pupil, iris, and eye chamber. The cornea plays a key role in a patient’s vision quality and optical health. The cornea works with the lens and anterior chamber to focus light to help you see clearly.
Why is corneal topography important?
Corneal topography, computer-assisted videokeratography (CAVK), or corneal mapping is a computer-assisted diagnostic imaging technique that helps in creating visuals of the corneal surface so that the doctor can view the visuals and analyze the entire shape of the cornea for diagnosis and treatment. It is a noninvasive medical imaging technique used for mapping the surface curvature of the cornea. Since the cornea is normally responsible for approximately 70% of the eye’s refractive power, its topography is of critical importance in determining the quality of vision. Therefore, corneal topography is an important diagnostic test.
How corneal topography is performed?
This corneal topography creates a map of the cornea that allows the physician to formulate a 3D perspective of the cornea’s shape.
- The corneal topography usually has a computer linked to a lighted bowl, which has a pattern of concentric rings.
- The patient is usually asked to sit in front of the bowl with their head pressed against a bar.
- Multiple light concentric rings are then projected on the cornea and the reflected image is captured on a charge-coupled device (CCD) camera.
- The computer software then digitizes these data points and prints out the corneal shape using different color representations to identify different elevations.
- The cool shades of blue and green are usually used to indicate flatter areas of the cornea.
- Warmer shades of orange and red may indicate steeper areas.
Are corneal topography and corneal tomography the same imaging techniques?
No, both are different diagnostic techniques. However, both are very useful in the diagnosis of keratoconus.
- Corneal topography usually provides a map of the front surface of the cornea that is used to evaluate its curvature.
- Corneal tomography also provides a map of the front surface, as well as additional information about the curvature of the back surface of the cornea (inside of the eye). It may also be used to create a map showing the thickness of different areas of the cornea.
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Medically Reviewed on 9/28/2022
References
Corneal Imaging: An Introduction:
(https://webeye.ophth.uiowa.edu/eyeforum/tutorials/Corneal-Imaging/Index.htm)
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