REFRACTIVE SURGERY

Refractive surgery using the excimer laser has, until now, been focused on corrections of the dioptric power of the cornea. That is, the refraction of the patient has been measured and then entered into the laser system to re-create a spectacle lens onto the surface of the cornea. There are a number of disadvantages to this approach, including:

Changing the shape of the cornea from prolate to oblate, which may contribute to less than optimal refractive results including higher order aberrations and decreased contrast sensitivity.

Not considering that the astigmatic component of the refraction is asymmetrical, and all astigmatic treatments using “standard” software programs are symmetrical, regardless of the manufacturer of the software may lead to localized irregularities post-operatively.

Taking excessive tissue in trying to re-create a lens onto the surface of the cornea.

Optical transition zones that do not take into consideration or register the real size of the scotopic pupil.

Surgeries planned by software that does not take into consideration the real shape of the cornea, which contributes more than 78% of the refractive power of the eye's optical system.

Principle 2
PROLATE SHAPE Calculation of the ideal surface, manifest
refraction and true elevation data from the AstraMax are used to calculate an ablation profile that yields an optimized prolate target surface for reduced higher order abberations. A
normal cornea is prolate and has an average aspheric “Q” value of -0.26. AstraPro preserves the preoperative prolate “Q” in primary treatments and restores the prolate “Q” in enhancements

.

Principle 3
OPTIMIZATION During the treatment process, the new shape is achieved with respect to the scotopic pupil size measured by the AstraMax. The AstraPro treatment covers the entire scotopic pupil, utilizing a blend zone outside the scotopic pupil. Surgeons may modify the OZ and TZ within the range of 3-9mm

.