Topography-Guided Custom Ablation (Contoura Vision): 22,000 Elevation Points

Every human cornea is as unique as a fingerprint, possessing microscopic hills, valleys, ridges, and astigmatic asymmetries that standard glasses prescriptions (Sphere and Cylinder) cannot capture.

The WaveLight Topolyzer Vario captures high-resolution Placido-disc reflections:

$$\text{Sampling Density: } \mathbf{22,000\ \text{Individual Elevation Coordinates Across 9mm Zone}}$$

The planning software (LYNX) converts these physical elevation discrepancies into an individualized ablation map, commanding the 500 Hz excimer laser to smooth out every microscopic corneal bump while simultaneously treating the refractive error.

A critical optical advantage of Topography-Guided (Contoura) over whole-eye Wavefront-Guided systems is Crystalline Lens Immunity:

• Wavefront aberrometers measure the whole eye—meaning aberrations inside the natural crystalline lens (which change dynamically with accommodation and age) are mistakenly ablated onto the cornea!
• Contoura treats only the cornea—the primary refractive boundary responsible for 80% of optical aberrations—leaving the internal crystalline lens untouched.

Standard LASIK centers the ablation over the geometric center of the entrance pupil. However, the eye's true Visual Axis (Line of Sight) is almost always displaced nasally relative to the pupil center: Angle Kappa ($\kappa$).

Ablating on pupil center induces artificial coma! Contoura Vision mathematically centers the ablation directly on the true Corneal Vertex (the visual axis reflection), virtually eliminating postoperative night halos and starbursts.