Can corneal topography diagnose the earliest stages of keratoconus?

Yes, often it can.

There is no hard, fast line between a normal cornea and one with keratoconus. Rather, it is a matter of degree of abnormality. Before the advent of digitized topography, keratoconus was only able to be detected once it was already seriously affecting both the cornea and vision.

Digitized topography provides a degree of detailed analysis of the corneal surface far beyond what had been possible before. Much to our surprise, it turns out that there were many, many cases where the cornea was not nearly as regular as earlier (and less sophisticated) technology suggested. An "in-between" or borderline cornea is considered to have Forme Fruste Keratoconus (FFK).

"Refractive procedures such as LASIK involve surgical alteration of the cornea, so it is important to screen for and identify abnormal corneas. These corneas often do not respond well to surgery. Even Forme Fruste corneas can be vulnerable.

Corneal technology has advanced even further than digitized surface topography, though. The Pentacam, for example, can perform the same topography on the BACK surface of the cornea as well as the corneal thickness at any position of the cornea. It has turned out that all of this data can also be useful in identifying and diagnosing early keratoconus or FFK.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic