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What is corneal topography?


Updated June 19, 2014

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What is corneal topography?
Photo © Troy Bedinghaus, licensed to About.com 2010
Question: What is corneal topography?
During my annual contact lens exam, my doctor charges an extra fee for corneal topography. What is corneal topography?
Answer: Corneal topography is a procedure used to monitor and measure changes that may occur to the shape and integrity of the cornea of your eye. A corneal topographer projects a series of illuminated rings onto the surface of the cornea, which are reflected back into the instrument. After analyzing the reflected rings of light, the computer generates a topographical map of the cornea. The images produced by the topographer can be helpful for your eye doctor when analyzing the health of your eyes.

So, what does corneal topography have to do with fitting contact lenses? Your eye doctor wants your contact lenses to fit your eyes as well as possible, and knowing the exact shape of your cornea is extremely important. Contact lenses that are too tight may constrict normal tear flow, creating an unhealthy environment for normal cell function. On the other hand, fitting a lens that is too loose may allow for excess movement of the lens on your eye, causing discomfort and possibly damage to the epithelial cells.

Wearing contact lenses requires a great deal of responsibility, by you and by your doctor. You must be diligent in following proper cleaning routines and wearing schedules. Your doctor must closely monitor small changes in your eyes in order to avoid potentially serious contact related complications.


Elliott, David B. Clinical Procedures in Primary Eye Care, Pp 115-116. Elsevier Limited, 2003.

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