To evaluate the efficacy, safety and accuracy of Contoura topography-guided LASIK & PRK in comparison to Wavefront optimized LASIK & PRK in virgin eyes with astigmatism.

In Upper Egypt, The second principal cause of blindness was uncorrected refractive errors accounting for 16% of sample population. It was reported that astigmatism (defined as cylinder power > 0.5 D) was the most common refractive errors in children and adults followed by hyperopia and myopia.

Laser vision correction has been established over the last 2 decades as a safe and effective intervention to treat refractive errors, being one of the main techniques practiced globally.

However, many subjects after LASIK had uncorrected distance visual acuity (UDVA) greater than 1.0, they complain about poor night vision, glare, and double vision. As studies have shown that every 1° deviation of the astigmatic axis could result in loss of correction of 3.3%. Even residual astigmatism less than 0.50D could have an actual impact on visual quality.

Excimer laser ablation used in the correction of refracted errors especially astigmatism may reduce quality of vision, and that is attributed to the induced optical aberrations. The most prevalent of these optical aberrations is the spherical aberration.

Among multiple sophisticated profiles that developed to optimize visual outcomes, wavefront optimized profile which compensate for corneal curvature to reduce spherical aberration.

The topographic guided profiles which consider the shape of the anterior corneal surface. Contoura topography guided ablation corrects astigmatic power and axis to create a more uniform, aberration-free cornea.

Treating astigmatism can be challenging as the conventional patterns of Excimer laser treatment of astigmatism is known to be less predictable than that of spherical refractive errors.

Inclusion Criteria:

• Astigmatism (up to 5.0 diopters) or less.
• Central corneal thickness (CCT) of 500 microns or more
• Estimated Residual stromal bed thickness (RSB) of 280 microns or more
• Subject has provided written informed consent

Exclusion Criteria:

• Keratoconus
• Abnormal topography
• previous ocular trauma or eye surgery
• pre-existing diseases of the vitreous, macula, or optic nerve that can affect visual outcome
• patients with uveitis and anterior segment pathology
• patients with corneal pathology or Severe dry eye
• pregnancy or breast-feeding females
• uncontrolled vascular or autoimmune disease

participants who are candidates and scheduled for excimer laser treatment either LASIK or PRK