Importance of the Annual Eye Examination III: Corneal Topography

eye exam

The Merriam-Webster dictionary defines topography as the practice of graphic representation on maps of natural and man-made features of a region in a way to show their relative positions and elevations. When topographic mapping of the eye is performed it is referred to as corneal topography.

Essentially, corneal topography is a detailed map of the entire cornea measuring the curvature, determining the amount of change of curvature (astigmatism), and providing details of the elevation of the front surface of the eye. Corneal topography is used when fitting patients in contacts, evaluating diseased corneas, and screening for corneal refractive surgery procedures. When it comes to fitting contact lenses the curvature of the contact lenses needs to align the curvature of the cornea to provide a good healthy fit.

The corneal topographer can assist in initial lens selection when fitting patients in contact lenses.  As discussed previously the autorefractor provides data on corneal curvature to screen for irregularities. If irregularities are suspected during the examination or screening processes, corneal topography is performed to further evaluate the cornea disease, such as keratoconus. These corneal diseases result in irregular astigmatism that makes it difficult for patients to see through conventional glasses and contact lenses.

The corneal topographer aids in the evaluation of these progressive corneal disease conditions as well as monitor for changes over time with differential maps. It also provides the necessary information for specialty contact lens selection for proper vision rehabilitation to provide the best visual potential possible for the patients with these conditions. Finally, this tool is used during the screening process for refractive surgery.

Refractive surgery, such as LASIK, is the process of removing corneal tissue to fix the refractive error present. The data gather aids in the screening process prior to the procedure to confirm that the patient is a good candidate for refractive surgery, reducing the risk of complications following the surgery.

Corneal topography is not indicated for every patient at their comprehensive eye examination, but it is a pertinent instrument to have to achieve the highest care for every patient that presents for their annual eye examination.

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