Refractive error is the inability of the eye to focus incoming light rays on the retina, thus not being able to create a clear image.
The curvature of the cornea plays a key role in bending the incoming light rays and focusing them on the retina. A too flat or too steep cornea will focus the light rays on the wrong plane creating a blurry image.
Refractive surgery aims to reshape the cornea with use of the excimer laser in order to correct refractive errors.
Refractive errors can be corrected either conservatively with glasses or contact lenses or surgically with refractive surgery procedures.
To be eligible for refractive surgery, one needs to be over 18 years of age and to have had stable refraction for at least 12 months. Contraindications for refractive surgery are severe dry eye syndrome, pregnancy, keratoconus and very thin cornea.
The two most popular types of refractive surgery procedures: the photorefractive keratectomy (PRK) and the femtosecond laser assisted LASIK (Femto-LASIK). Their main difference is that the LASIK involves creation of a corneal flap. Both techniques make use of the excimer laser to reshape the cornea. In Femto-LASIK a thin corneal flap is created with the excimer laser and then the cornea is treated and the flap repositioned. In PRK the superficial corneal layer is mechanically removed during surgery and left to regenerate on its own. The trans-PRK is the latest form of “no-touch” surface laser treatment where the corneal epithelium is removed with the use of the excimer laser as opposed to the mechanical removal with the traditional PRK. Results are found to be equal between PRK and trans-PRK but healing seems to be slightly faster with the latter technique.
All above mentioned refractive surgery techniques deliver excellent outcomes with a success rate of more than 99%. The treatment is individualized and the surgeon will discuss with the patient all possible options explaining advantages and disadvantages of each method. PRK involves postoperative discomfort for a few days but is regarded more suitable for patients with intense sport activity.
There is no age limit for performing laser refractive surgery. Above the age of 40 presbyopia occurs and therefore the patient loses his ability to read close up. In the age group above 40 the so-called monovision is preferred, where the dominant eye is corrected for far distance and the other eye left slightly shortsighted to allow for reading ability. Final option for this age group is the clear lens extraction, where a cataract surgery is performed followed by implantation of a multifocal lens that allows for good vision in all possible distances.
Refractive errors include myopia, hypermetropia and astigmatism