While all men are created equal, our corneas are not. Presurgical testing for refractive surgery must include corneal topographies, Orbscans and Pachometry to determine corneal thickness. Examination of these results must be done carefully to first; determine the correct measurements of the cornea second; evaluate corneal health, and third; differentiate between corneal disease and unusual but healthy corneas.

One such finding of an unusual but healthy cornea, is called Displaced Apex syndrome. Many eye care practitioners assume that a patient’s line of site, pupillary center and corneal apex are all in a straight line. This however, is not always the case. The importance of these findings can not be over emphasized. Each one must be determined and the surgical procedure must take them all into account in order to have a successful outcome.

Common mistakes include false positives for Keratoconus or irregular astigmatism. In order to properly evaluate the cornea its thickness must be determined, anterior and posterior elevations as well as anterior and posterior sagital curvatures are required. Comparison of elevation and curvature maps will permit the doctor to accurately differentiate true pathology from false positives.

Simply looking at the front surface of a cornea can lead one to falsely diagnose Keratoconus because of an irregular appearance and an inferior “conic appearance.” However, examining the posterior elevation maps will allow the practitioner to rule out a false positive. If the front surface shows this irregularity, then a true Keratoconus patient will demonstrate the same result on the back surface. However, if the posterior corneal surface is completely normal while demonstrating the steepening anterior surface then a true diagnosis of Displaced Apex Syndrome must be made. This is significant because there is no pathology, refractive surgery can be performed and the calculations must be made in order to account for the different shaped cornea.

Displaced Apex Syndrome results in the apex of the cornea not aligning with the line of sight and/or pupillary axis. Once the correct diagnosis is made; all the rest of the answers fall into place. Missing this very important anatomical characteristic will cause the patient to have terrible refractive surgical results. Most of the surgeons that I have spoken with will chose PRK for these patients as the best procedure.

As always, before having surgery make sure the doctor is very experienced and is familiar with all forms of testing AND knows how to read these results.