Laser techniques: PRK and presbyLASIK

The specifics of presbyopia surgery depend on the patient’s pre-existing distance vision, but the general principle is the same: the curvature of the cornea (the eye’s natural lens located in front of the crystalline lens) is modified by reshaping its intermediate layer (the stroma) with a laser beam.

The two main refractive laser surgery methods are PRK (Photorefractive Keratectomy) and PresbyLASIK.

• PRK: The outermost layer of the cornea (the epithelium) is delicately removed to access the stroma.
• PresbyLASIK: A small flap (“stromal flap”) is created in the corneal epithelium, usually using a femtosecond laser.

The choice of technique depends on the patient’s professional and sports activities, as well as corneal characteristics, especially thickness. A thorough preoperative assessment is essential to select the most appropriate laser method.

Surgical strategies based on pre-existing refractive error

Presbyopia surgery for previously myopic patients

For presbyopic patients with prior myopia, three surgical strategies are possible:

• Monovision: The dominant eye is corrected for distance vision, while a slight myopia is maintained in the other eye for near vision.
• Binocular Vision: Both eyes are treated similarly, with the central corneal zone dedicated to near vision and the peripheral zone to distance vision.
• Multifocality: Each eye is given both distance and near vision, but with a preference for distance vision in the dominant eye and near vision in the non-dominant eye.

Preoperative tests with contact lenses help determine the most suitable solution for each patient.

Presbyopia surgery for hyperopic patients

For hyperopic patients, multifocal vision is generally the most suitable solution.

Presbyopia surgery for emmetropic patients (no prior refractive error)

In emmetropic patients, unilateral surgery is most often performed on the non-dominant eye to restore both near and distance visual acuity.

PRELEX for myopic patients

Monovision is one possible method, particularly for patients with high myopia or those already using this approach with contact lenses. For mild to moderate myopia, multifocality is often preferred.

PRELEX for hyperopic and emmetropic patients

In these cases, multifocality is generally the best solution. Multifocal diffractive trifocal implants are used, consisting of concentric steps that split light into different focal points for distance, intermediate, and near vision.

When should presbyopia surgery be considered?

There is no universal rule, but regular ophthalmological follow-up is necessary, as presbyopia eventually affects everyone. It is recommended to consult a specialist every 5 years before age 45, then every 2 years thereafter.

The decision to operate is subjective and is based on the extent to which presbyopia interferes with daily life. Surgery is considered when corrective lenses are no longer sufficient or when the patient wishes to be free from glasses or contact lenses. The presence of other vision problems may also influence the timing of surgery.

Why not always choose LASIK over PRK, given the lighter postoperative course?

PRK requires a longer recovery period because the corneal epithelium, removed at the start of surgery, must regenerate. In LASIK, the stromal flap is repositioned at the end of the procedure, allowing for faster recovery.

However, LASIK is not always the best option. For example, if the corneal thickness is less than 500 microns, PRK is preferred to ensure sufficient mechanical stability of the cornea. LASIK is also not recommended for people at high risk of ocular trauma (due to their profession or sports), as the stromal flap permanently weakens the cornea. In such cases, PRK is safer, as the cornea regains greater strength after healing.