Corneal Topography Exam for Laser Vision Correction & Keratoconus
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The EyeMap machine.
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Corneal topography is the most accurate tool available for measuring corneal curvature. It produces a map of the surface of the cornea and provides essential information about the cornea's shape, distortions, and astigmatism for patients considering refractive surgery or who are suffering from keratoconus. At NVLC we use the Alcon EyeMap® EH-290, a state-of-the-art corneal topographer from one of the leading manufacturers of ophthalmic instruments.
The EyeMap machine may look intimidating with its black-and-white spiral, but don't worry -- it's a fast, easy and painless test. All you have to do is place your hands on the table, rest your chin on the ledge and lean your head on the bar. The technician will ask you to blink a few times so the natural tear film on your eye is as uniform as possible, and then to open your eye wide. The machine will buzz a little and snap a picture. You'll see bright rings of light, and that's all.
Image of a patient's cornea on the EyeMap computer.
Click image to enlarge. |
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Those light rings are shining into your eye and reflecting back into the EyeMap machine. Distortions in your cornea bend the rays of light, so when they bounce back, they arrive in slightly different positions. Computer software analyzes the shifted light, calculates the surface characteristics of your cornea, and produces a highly detailed image.
Within a few seconds you'll be able to see the image on the monitor. Different colors represent irregularities on the surface of the cornea like mountains and plains in a landscape. Blue and green indicate flatter sections of your cornea, while pink and red signify steeper areas.
If you undergo laser vision correction, this data will be fed into the laser and possibly combined with a CustomCornea Wavefront result to improve the outcome of your vision procedure. If you're being treated for keratoconus, this information will be used to craft your contact lenses.
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