Photorefractive keratectomy in mile keratoconus type of corneal surface ablation in for correct refractive error

Topo-guided photorefractive keratectomy will be performed using an excimer laser (Allegretto Wave Topolyzer, Alcon, Inc.) with a 6 mm optical area and a transition area of 2 mm in all eyes. At that point, the partial topography-guided photorefractive keratectomy laser treatment will be finished. The arrangement will be to treat 70% of the cylindrical and spherical part to not surpass 50μm of stromal expulsion. The estimation of 50μm as the most extreme removal depth recommended by Kanellopoulos in Athens protocol will be chosen

Visual acuity (VA) commonly refers to the clarity of vision

Optical aberrations are a major cause for poor quality of vision. It occurs when light from one point, after transmission through an optical system, does not converge to or diverge from a single point. Any deviation of the optical system from paraxial optics results in aberrations. In the eye, the various refracting surfaces like tear film, cornea and lens are primarily responsible for inducing ocular aberrations. The difference in shape of the wave-front entering the eye and that exiting the eye defines the type of aberration. The ocular aberrations are classified into lower order aberration (LOA) (zero order- piston; first order- horizontal and vertical tilt; second order- spherical defocus and astigmatism) and higher order aberrations (HOA) (third order - coma and trefoil; fourth order - quatrefoil, secondary astigmatism and spherical aberrations; fifth order - pentafoil; sixth order - hexafoil).