Just as each individual has a unique appearance, each eye has its own optical prescription.

However, when optical prescriptions are measured in a conventional manner, people with the same optical prescription are prescribed the same glasses and contact lenses (e.g. two myopia diopters (prescription of -2.0).

Glasses, contact lenses and conventional refractive surgery correct myopia, hyperopia and astigmatism which represent so-called low-degree aberrations.

There are other components of refractive errors called high order aberrations that make everyone's vision unique.

These components partly explain the halos and glare. By using a device called an aberrometer, it is possible to measure those components of the vision that are usually not corrected by conventional laser surgery.

The measurements obtained can be integrated into the ablation profile programmed in the laser system in order to carry out a personalized treatment and to correct in addition to low-degree aberrations (myopia, hyperopia, astigmatism) high-degree aberrations, such as coma, trefoil or spherical aberration. Personalized treatments are neither indicated nor necessary in all cases. Hyperopia and astigmatism are usually best corrected with personalized treatments.