Ablative Refractive Surgery 

Corneal Laser

These procedures use excimer or femtosecond lasers to reshape the cornea and correct refractive error.

Importance of Quality Corneal Topography

Before any refractive surgery, the critical first step is to obtain a high-quality corneal topography. This study allows for an accurate assessment of corneal curvature, symmetry, and thickness, determining whether the patient is truly a candidate for surgery and which technique is the safest and most effective.

Unreliable topography due to poor equipment calibration or recent contact lens use can skew the results, giving a false impression of corneal shape and compromising surgical safety.

Discontinuing Contact Lens Wear Before the Study

To ensure reliable measurements, it is essential to discontinue contact lens wear for an appropriate amount of time before performing the topography:

• Soft lenses: Discontinue at least 3 to 5 days before the study.

• Toric lenses (for astigmatism): Discontinue 7 to 10 days before.

• Rigid gas permeable lenses: Discontinue 3 to 4 weeks before.

• Ortho-K/CRT (corneal molding): Discontinue treatment for 4 to 6 weeks, or longer if the cornea has not stabilized.

This time allows the cornea to return to its natural shape, ensuring that the evaluation is accurate to its actual condition and allowing for safe surgical planning.

A. First Generation: PRK (Photo-Refractive Keratectomy)

Technique: The corneal epithelium is removed, and the excimer laser is applied directly to the stroma.

Advantages:

Good for thin corneas.

No risk of flap complications (as with LASIK).

Disadvantages:

Greater postoperative pain.

Slower recovery (up to 1 week of blurred vision).

Indications:

Low to moderate myopia.

Patients with occupational risk (military, contact sports).

B. Second Generation: LASIK (Laser-Assisted In Situ Keratomileusis)

Technique: A corneal flap is created with a microkeratome or femtosecond laser, then an excimer laser is applied to the stroma.

Advantages:

Fast recovery (24-48 hours).

Less postoperative discomfort than PRK.

Disadvantages:

Risk of flap complications (dislocation, epitheliopathy).

Not recommended for thin corneas or keratoconus.

Indications:

Myopia, hyperopia, and astigmatism.

C. Third Generation: Lenticular Surgery (without Flap)

These techniques remove an intrastromal lenticule instead of surface ablation.

1. SMILE (Small Incision Lenticule Extraction)

Technique: A femtosecond laser creates a lenticule that is extracted through a small incision (no flap).

Advantages:

Less dry eye than LASIK.

Safer for thin corneas.

Disadvantages:

Does not treat hyperopia (only myopia and astigmatism).

More expensive technology.

2. SmartSight (Technique similar to SMILE, but with greater customization)

Technique: Similar to SMILE, but with advanced algorithms for greater precision.

Advantages:

Greater preservation of corneal biomechanics.

Option for irregular corneas.