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A Quadrant Elevation Map is defined as a color-coded topographical display that shows the height of the cornea relative to a "Best Fit Sphere" (BFS) in four distinct quadrants. Used in devices like the Pentacam or OCT: it reveals:
A curvature map tells you how "steep" the eye is; but an elevation map tells you where the tissue is physically "pushed forward" or "recessed." This is critical because some eyes can be steep but "normal;" whereas an elevation map that shows a "red spot" (high elevation) in one quadrant is a definitive sign of corneal thinning or disease.
Keratoconus usually causes the cornea to bulge in the "inferior-temporal" quadrant. By looking at the elevation map: the surgeon can see:
The map uses a standard "traffic light" color scale:
Yes. Surgeons use quadrant elevation maps to choose the best intraocular lens (IOL). If the map shows significant elevation differences between quadrants (asymmetry); a standard lens might not provide clear vision. Instead: the surgeon may opt for a "Toric" lens or a specialized "Aspheric" lens to correct for the eye's unique shape.
No: elevation maps are created using non-contact technology. A Scheimpflug camera (like the Pentacam) or an OCT (Optical Coherence Tomography) uses light or rotating cameras to take thousands of measurements in a few seconds while you simply look at a target light.
This map is the "safety check" for LASIK. If the elevation map shows even a tiny red spot on the "back" of the cornea; it could mean your eye is too weak for laser surgery. Performing LASIK on such an eye could cause "ectasia;" where the cornea begins to bulge uncontrollably after the surgery.
Yes: if you have a condition like Keratoconus or if you rub your eyes frequently; the elevation values can change. Doctors often compare "difference maps" from one year to the next to see if the red spots are getting larger or higher; which would indicate that the eye disease is progressing.