Preoperative Assessment
for Laser Refractive Procedure

A thorough and comprehensive preoperative assessment is crucial for the success of a laser refractive procedure, aimed at correcting refractive errors (myopia, hyperopia, astigmatism). During the preoperative evaluation, all the necessary data is collected and analyzed to help the refractive surgeon determine whether the candidate is suitable for laser surgery and which method should be applied (Femto – LASIK or trans PRK). Factors considered, include the condition of the cornea, the stability of vision, the overall health of the eyes, and the candidate’s daily activities.

The final selection of the method is made after an extensive discussion between the candidate and the refractive surgeon. Candidates who wear contact lenses must remove them for at least one week before the preoperative assessment.

Corneal topography is a specialized diagnostic examination that through detailed color and 3D maps, provides valuable information and results about the shape, curvature, and contour of the cornea. In a corneal topography, specific color scales (elevation, pachymetric, and keratometric map displays) define the distribution of the refractive power of the cornea’s anterior and posterior surfaces. Just as colors on a geographic map depict the terrain’s morphology (e.g. elevation), a topographic map of the cornea shows areas with higher or lower refractive power. Warm colors (e.g. red, purple) represent steep or irregular areas, while cooler colors (e.g. green, blue) depict smooth and flat surfaces.

Corneal topography is a very quick and completely painless examination, and is the cornerstone of planning a laser refractive procedure. It is worth mentioning that corneal topography can diagnose serious eye conditions such as keratoconus and also other corneal abnormalities or dystrophies.