Text author: Dr sc. Bojan Kozomara, dr med.
Laser vision correction surgery has been practiced for over 40 years and has been chosen by over 50 million people worldwide to correct refractive anomalies in their eyes. If you were to ask some of these patients today, the vast majority would agree that they measure time before and after the surgery, at least when it comes to the quality of their vision.
There is no reason for fear, as all techniques of this surgical procedure are computer-controlled with the help of precise software programs. This computer precision, combined with the experience of our doctors, guarantees a safe surgical procedure.
Today’s lasers can correct diopters from -9 to +4, and ±5 diopters of astigmatism, which means that practically 95% of people with refractive anomalies of the eye are candidates for surgery. For patients whose diopters exceed the aforementioned values, or who have corneal tissue that is too thin, a method of implanting phakic intraocular lenses has been developed, yielding results that are equally good as those of laser vision correction (often better for individuals with high diopters, as the lenses improve image quality).
Over the past 20 years and more, significant efforts have been made to improve the techniques used in laser vision correction surgeries. Among all the advancements, two have become the most popular through the evolution of procedures, numerous scientific studies, and technological advancements: PRK and LASIK, with Femto LASIK also being added.
Photorefractive Keratectomy (PRK) is the first laser vision correction technique. This method is based on the removal of the epithelium (the surface part of the cornea) with a laser (Transepithelial PRK; T-PRK) and diopter correction through ablation (micron-scale remodeling) of the corneal stroma. It is suitable for corrections up to -4 diopters of the sphere and up to -1.50 diopters of the cylinder, while it is not recommended for the correction of + diopters. It is primarily advised for patients who have thin corneal tissue and for whom other diopter correction methods are not advisable. The drawback of this method is a somewhat longer postoperative recovery. Specifically, the regeneration of the corneal epithelium that is removed during the surgery can take up to 10 days, which may cause the patient to experience blurred vision, irritation, and tearing.
Currently, the most popular and frequently used method of laser vision correction is Laser Assisted In Situ Keratomileusis (LASIK). This method corrects diopters in over 95% of cases, making it indispensable in refractive eye surgery. Unlike the PRK method, in LASIK, the epithelium is not removed. Instead, a flap is created on the surface of the cornea through an incision. This flap is lifted from the cornea, the stroma is reshaped with a laser to correct the diopter, and then the flap is placed back in its original position on the eye. Due to this method of diopter correction, LASIK can correct minus diopters up to -9, plus diopters up to +4, and astigmatism up to ±5 diopters. Another advantage of LASIK is the significantly faster postoperative recovery. Patients can return to most of their daily activities within 1-2 days after the procedure, with virtually no pain, blurred vision, or eye tearing. The only potential drawback of this method is the presence of the incision on the corneal surface, or the “flap,” but its stability is exceptional, with only theoretical chances of displacement after surgery.
Creating a flap on the surface of the cornea can be done in two ways: with a microkeratome (a specially designed blade) or with a laser. Femto-LASIK employs the latter method, creating the flap with a laser rather than a blade. Although there is ongoing controversy over whether the femto option is genuinely better than the microkeratome, the preference for the Femto method has been increasing year by year. The rest of the diopter correction process is the same for both procedures.
Before any laser vision correction surgery, a detailed examination of the front and back parts of the eye is performed, with a special focus on the condition of the cornea. The exact visual acuity and the refractive anomaly of the eye are determined. The cornea, lens, and retina are examined, and special diagnostics are used to analyze the thickness and curvature of the cornea in detail, as well as any irregularities or scars that may affect the final decision about the surgical procedure.
Only after all these examinations is the patient informed about the condition of both eyes, the possibilities for correction, the procedure itself, and the postoperative recovery. The decision to proceed with the surgery is always a mutual one.
Before the procedure itself, the eyes are anesthetized by instilling anesthetic drops, which is the only anesthesia needed. The patient is advised to focus their gaze on the light they see above their eye. They are also required to remain as still as possible, not to squeeze their eye or move their head. Even if the eye moves during the operation, modern lasers have a so-called tracking system that monitors even the smallest eye movements, thereby eliminating the possibility of the laser reshaping a part of the corneal stroma that is not intended for that purpose, or damaging the eye in any way.
First, the right eye is operated on, followed immediately by the left eye. The operation is completely painless.
Immediately after the procedure, the patient goes home, with the advice to rest a bit longer that day. The eyes should not be rubbed or scratched, and drops should be instilled based on the instructions given before leaving the hospital.
Depending on the method used to correct the diopter, recovery can take from 2 to 10 days. The LASIK method, as previously mentioned, shortens the recovery time, and patients usually return to most of their daily activities after 2 days. On the other hand, recovery with the PRK method is somewhat longer. Vision may be blurred for 5-6 days, and protective contact lenses are typically worn during the same period. Full visual acuity is achieved only after 10 days.
