Laser-Assisted In Situ Keratomileusis, known as LASIK, is the most common type of laser eye surgery. It is used to treat nearsightedness, farsightedness, and astigmatism.
According to the United States Food and Drug Administration, the procedure entails a number of unavoidable risks and complications in some patients.
The most common complication is dry eyes.
Contents of this article:
What is LASIK?
Laser eye surgery is a popular way of correcting vision.
The LASIK procedure starts with the surgeon applying eye drops to numb the eye and then propping open the eyelids using an instrument called a lid speculum.
The surgeon creates a thin flap in the cornea - the eye's outermost layer - which is temporarily folded away.
Using a computer-controlled laser, pulses of light are focused on the eye, and these reshape the cornea.
Finally, the LASIK surgeon repositions the corneal flap, and this will begin to heal on its own within hours.
People undergoing LASIK usually feel pressure on the eye, an itching sensation, or slight burning, but the procedure is not usually painful.
Why might LASIK lead to dry eyes?
The most common complication of LASIK is dry eyes.
A 2011 study noted that 95 percent of patients develop some degree of dryness immediately after having the procedure, with a small proportion of patients developing chronic dry eyes that do not respond to traditional treatments for dry eye disease.
As many as 60 percent of patients still report dry eye symptoms 1 month after having LASIK. The symptoms usually peak in the first few months after surgery and begin to improve 6 to 12 months following surgery.
Experts have suggested different reasons why people might get dry eye after having LASIK.
One reason could be damage to the corneal nerves. Nerves in the eye are disrupted both when the LASIK surgeon creates the corneal flap and when the laser reshapes the cornea.
Another possible cause is that the creation of the corneal flap could also damage cells in the eye called goblet cells.
Inflammation to the nerve endings in the eye after the procedure could also cause dry eye, or make existing symptoms of dry eye worse.
Alternatively, the change to the shape of the cornea in LASIK may alter the fit of the eyelid against the surface of the eye. This could lead to tears being distributed unevenly over the eye when blinking.
Who is most at risk?
There is no way to predict how severe the symptoms of dry eye might be for patients who decide to have LASIK.
Experts do know, however, that patients who already have symptoms of dry eye before having LASIK are more at risk for prolonged and severe dry eye symptoms following the procedure.
Studies have shown certain people have a higher risk of dry eyes following LASIK. This includes women, individuals of East Asian ethnicity, contact lens wearers, people with chronic eyelid conditions, certain immune system disorders, and diabetes.
People who require more aggressive vision correction during LASIK are also likely at risk.
Can people with dry eye syndrome get LASIK?
People who undergo LASIK often have symptoms of dry eye before having the procedure. Between 38 and 75 percent of people who seek LASIK surgery have these symptoms, mostly due to contact lenses irritating the eyes.
Treatment and prevention of dry eyes following LASIK
Conventional treatments for dry eyes work for most patients who experience these symptoms after undergoing the LASIK procedure.
Eye drops can help to ease the discomfort of dry eyes.
The lubricant eye drops known as artificial tears are usually the first treatment a doctor will recommend. However, some patients may not respond sufficiently to artificial tears.
A procedure called punctual occlusion may be effective for these patients. In this procedure, silicon or collagen plugs are inserted into an area of the eye. The aim is for these plugs to keep tears in the eyes for longer.
Punctual occlusion is considered by experts to be safe and effective, and the procedure can be reversed.
Because inflammation is a component of dry eye disease, anti-inflammatories are often used to treat moderate-to-severe symptoms.
Cyclosporine eye drops have been found to increase tear production, decrease inflammation, and raise the numbers of goblet cells in people who have dry eye.
If these treatments do not work, other options include autologous serum eye drops and scleral gas-permeable contact lenses.
Autologous serum eye drops consist of a patient's own serum, which is an element of blood, mixed with sterile saline solution.
Scleral lenses are wider than normal contact lenses. They sit on the white part of the eye and help to keep eyes moist by holding a reservoir of fluid between the lens and cornea.
Other complications following LASIK
Some people who have LASIK may also experience problems with the corneal flap made by the surgeon, such as infections, excess tears, and inflammation.
Other complications associated with LASIK include not being able to see as sharply or clearly as before, or rarely, losing vision.
Vision might also return to pre-surgery levels slowly. This can sometimes happen to patients who are pregnant or who have hormonal imbalances.
Glare, halos around bright lights, and double vision have also been reported as side effects following LASIK.
It is possible that the laser could under- or overcorrect vision if too little or too much tissue is removed from the eye.
Undercorrections are more common among people who are nearsighted who have LASIK. Overcorrections tend to be more difficult to fix than undercorrections.
Other options for correcting vision
Orthokeratology (Ortho-K), otherwise known as overnight vision correction, is one alternative to laser eye surgery. Practitioners claim that this method gives the benefits of LASIK without the surgical risks.
Overnight vision correction involves wearing specially designed contact lenses during the night while asleep.
Similar to LASIK, these custom-built contact lenses reshape the cornea to correct vision, but without the use of surgery. It usually takes one to four weeks for results, and the results are typically not permanent. Overnight lenses often need to be worn intermittently as a result.
A recent systematic review looked at the evidence for this method and concluded that orthokeratology is a safe and effective treatment if lenses are fitted properly and lens care regimens are rigorously adhered to.
The review found that the most common complication of orthokeratology is staining of the cornea.