LASIK, an acronym for Laser-Assisted In Situ Keratomileusis, is a refractive procedure that reshapes the cornea to correct nearsightedness, farsightedness and astigmatism. It is the most common type of refractive surgery. Using targeted laser beam energy, the LASIK procedure reshapes the cornea so that light rays are focused more precisely on the retina, producing clear, sharp vision.
Candidates Eligible For LASIK
LASIK is considered a safe procedure, yet it is not ideal for everyone. A thorough medical evaluation of the patient’s eyes must be performed to determine whether the LASIK procedure is appropriate. Good candidates for LASIK are patients who:
- Are over 18 years old
- Not pregnant or nursing
- In general good health
- Have had stable vision for at least 6 months
- Have healthy corneal tissue, thick enough for a flap
- Have refractive errors that fall within the treatable range
It is also important for patients to fully understand the details and risks of the procedure, and to maintain realistic expectations for the outcome.
Benefits Of LASIK
One of the primary benefits of LASIK is that patients immediately experience improved vision after surgery. For many people, laser eye surgery can correct their vision sufficiently to permit them to perform all, or most, of their daily activities without eyeglasses or contact lenses. Approximately 90 percent of patients who have undergone LASIK achieve 20/20 to 20/40 vision as a result of the procedure.
LASIK has the advantage of being a short procedure that results in permanent vision improvement. Most patients who choose to undergo LASIK achieve clear vision without corrective lenses while also benefiting from minimal downtime and only mild post-operative discomfort.
The LASIK Procedure
LASIK is performed on an outpatient basis using only numbing eye drops to reduce any potential discomfort. The entire surgery takes less than 5 minutes to perform, although patients can expect to spend a few hours at the doctor’s office. If requested, patients can receive an oral sedative prior to surgery to reduce any anxieties about the procedure.
During the LASIK procedure, the patient lies down in a reclining chair as the doctor positions the laser precisely over the eye. A speculum is used to keep the eye open while the eye is cleaned and anesthetic eye drops are administered. A corneal flap is created with either a blade or a laser. The surgeon gently lifts the surface of the cornea aside, enabling the excimer laser to reshape the curvature of the cornea.
The excimer laser delivers customized pulses of light energy based on each patient’s prescription. The measurements for customization are determined prior to surgery, with the precise positioning confirmed prior to the start of the procedure. The second eye is treated immediately after the first. Following the surgery, the patient is provided with a protective shield to protect the eyes from bright lights.
Risks Of LASIK
Any surgical procedure carries some risks, and patients should be aware that changes to the cornea made during LASIK cannot be reversed. Nonetheless, LASIK is considered safe for most eligible patients. While rare, complications may occur after the procedure, including:
- Undercorrection or overcorrection of vision
- Dry eyes
- Flap complications
- Postsurgical infection
- Increased sensitivity to light
- Visual problems, such as halos or night glare
- Fluctuating vision
Only 1 percent of patients undergoing LASIK experience complications.
Recovery After The LASIK Procedure
After LASIK, patients rest in the ophthalmologist’s office for a short time before having someone else escort them home. Medication may be prescribed to relieve any discomfort experienced during the first 24 to 48 hours after surgery, but most patients tolerate this procedure well. The doctor will likely recommend a few hours of rest after treatment. Most patients are able to return to work and other regular activities the very next day. Patients who have undergone LASIK are instructed to avoid strenuous activities for at least a week.
Typically, patients experience a significant improvement in their vision immediately after the procedure, but the full benefits of LASIK may not be apparent for several months. While patients can achieve clear vision from LASIK, this procedure does not prevent the development of presbyopia, the age-related vision changes that occur after the age of 40. Many patients will need reading glasses for this condition, but their distance vision will remain clear.
Photorefractive Keratectomy (PRK)
Photorefractive keratectomy, or PRK, is a laser vision correction procedure that reshapes the cornea to correct mild to moderate conditions of myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. It is the second most common type of laser eye surgery after LASIK. While during LASIK a flap is created to access the cornea, during PRK the entire epithelial layer of the cornea is removed and later allowed to grow back. During both processes, the cornea is reshaped to provide vision correction.
Advantages Of PRK
Compared to LASIK, PRK provides the surgeon with greater control over the location and amount of tissue being removed, which permits more precise results. PRK gently sculpts the cornea rather than cuts, maintaining corneal strength while providing impressive vision correction.
Other advantages of the PRK procedure include:
- Less depth of laser treatment
- No corneal flap complications
- Ability to be performed on thin corneas
The PRK procedure offers distinct benefits to individuals whose activities put them at elevated risk of eye injury (boxers, for example) and for patients whose corneas are too thin, or whose pupils are too large, to permit LASIK. PRK also avoids not only the complications from corneal flaps, but a serious complication of LASIK known as corneal ectasia, which can result in distorted vision and even permanent vision loss.
Disadvantages Of PRK
While PRK may be a preferable to LASIK surgery for some patients, there may be disadvantages to the procedure as well, including:
- More discomfort for the first few days after surgery
- Longer recovery period
- Greater risk of postsurgical eye infection
- Greater risk of temporary or permanent haziness of the cornea
Both LASIK and PRK have comparable rates of vision improvement and carry some of the same risks, so a serious consultation with the ophthalmologist is necessary to determine which surgery will be most beneficial to the individual patient.
The PRK Procedure
Before the PRK procedure begins, the eyes are numbed with anesthetic eye drops. The surgeon then uses an excimer laser, with targeted laser energy, to reshape the cornea. The surgeon has complete control over the laser throughout the procedure, for a highly precise and customized result, designed to give each patient the best vision possible.
The entire procedure takes only a few minutes to perform. Because of the potential for blurred vision for a time after PRK, the surgery is often performed on only one eye at a time, with the surgeon waiting to schedule the second eye until the vision in the first has adequately cleared.
After the procedure, the eyes are bandaged with a soft contact lens to protect the cornea. New cells will grow back over the next few days to replace the cells that were removed. The contact lens will be removed by the surgeon in a follow-up examination.
Recovery After The PRK Procedure
After the PRK procedure is completed, patients are instructed to rest before returning home. They may required to wear eyeglasses after the procedure until their vision has stabilized. The surgeon prescribes eye drops to prevent infection and keep the eyes moistened.
While vision may improve immediately after the PRK procedure, full results may take several days or weeks to become apparent. Strenuous exercise should be avoided for at least a week because this can interfere with the healing process. Patients will likely be able to see well enough to drive a car after 2 to 3 weeks.
Results After The PRK Procedure
The results of PRK are considered comparable to those of LASIK. Some patients may experience only 20/40 vision and may still need glasses or contact lenses after their procedure. PRK does not correct presbyopia, a natural change in the eyes that affects people over the age of 40. Patients who require glasses for reading will continue to need them after surgery. It is important for patients to maintain realistic expectations of the results of any laser surgery if they are to be satisfied with the results.
Risks Of PRK
As with any type of surgery, there are certain risks associated with the PRK procedure, including:
- Postsurgical infection
- Adverse reaction to anesthesia
- Inaccurate vision correction
- Sensitivity to light
- Problems with night vision, such as halos
- Hazy vision
- Dry eyes
Many of the complications that may arise after PRK are similar to those that may occur after any type of refractive surgery.