PRK and LASIK: What are the differences?

Which visual defects can be treated with eye surgery?

Laser eye surgery can treat all visual defects. Treatment differences primarily relate to the type and severity of the defect requiring correction.

 

PRK or LASIK can be used in cases of:

  • mild and moderate myopia;
  • presbyopia;
  • mild and moderate hyperopia;
  • mild, moderate and high astigmatism;

However, some cases don't involve excimer lasers, but rather the implantation of a lens behind the iris.

 

This is the case if the patient is:

  • highly myopic;
  • experiencing coexisting presbyopia and high hyperopia;
  • has a history of previous radial keratotomy or penetrating keratoplasty surgeries;

In most cases, the main choice is LASIK or, for specific corneal situations, PRK;

 

The minimum age for the procedure depends on the visual defect, which must have been stable for at least one year. It can be performed at:

  • 25 years of age for myopia;
  • 18 years of age for astigmatism;
  • 18 years of age for hyperopia;
  • 45 years of age for presbyopia;

What are PRK and LASIK?

PRK

Acronym for "Photo Refractive Keratectomy", PRK uses a single excimer laser to remove tiny amounts of tissue from the corneal stroma through ablation. This technique is now primarily used for patients with thin corneas. PRK corrects myopia, hyperopia, astigmatism, and rarely, presbyopia.

 

LASIK

LASIK corrects myopia, astigmatism, hyperopia, and presbyopia.

LASIK stands for "Laser-ASsisted In situ Keratomileusis". It combines excimer laser use with the creation of a "corneal flap" using a femtosecond laser to optimize correction. LASIK is indicated for all types of visual defects except high or very severe defects, which generally require intraocular lens implantation. Some cases of high myopia can be treated with LASIK but require ophthalmologist evaluation.

 

PRK and LASIK procedures

PRK

The PRK procedure begins with the patient seated, receiving anesthetic eye drops, and a blepharostat holding the eye open.

The superficial corneal layer (epithelium) is removed, and the excimer laser reshapes the cornea to focus images on the retina. The PRK laser acts directly on the eye's surface, unlike LASIK's corneal flap creation.

 

LASIK

LASIK is a combined technique. It involves creating a corneal flap with a femtosecond laser to protect the underlying correction, making it cleaner, simpler, and painless. The patient is prepared similarly, with a blepharostat and anesthetic eye drops. The ophthalmologist creates the corneal flap and reshapes the cornea with the excimer laser.

 

The main difference between LASIK and PRK lies in laser use. In PRK, the cornea is reshaped directly; in LASIK, this happens after flap creation. Both LASIK and PRK take about 15 minutes per eye. Post-treatment, patients rest for half an hour before a check-up and discharge.

 

PRK and LASIK recovery time and convalescence

PRK

PRK recovery is longer, with pain relief taking 10-15 days and visual acuity recovery taking a month. "Haze," a complication causing blurred vision due to incorrect corneal healing, may occur, more frequently after high myopia surgeries. Post-PRK haze can be mitigated by following post-operative advice and using mitomycin.

 

LASIK

With LASIK, daily activities can resume after 3 days, as post-operative pain is absent. Minor discomfort may occur, usually resolving the day after surgery. Full visual acuity is regained after 7 days, if post-operative advice is followed.

 

Pain related to PRK and LASIK

Neither procedure is painful during the intervention. Both are designed to minimize patient discomfort during the operation.

 

However, PRK is more uncomfortable and painful in the following days; LASIK is painless, with only minor discomfort that quickly subsides.

 

LASIK or PRK: which is the best technique?

The best choice is determined after a thorough eye examination (refractive assessment) to understand the appropriate procedure.

 

This assessment determines the presence of dry eye syndrome or keratoconus (which may preclude treatment) and corneal thickness, influencing the choice between LASIK and PRK.

 

A preliminary consultation addresses patient questions and evaluates suitability for surgery.