Definition and Overview
Lasik surgery is one of the several advanced ways of treating refractive errors. It involves strategically and carefully removing a portion of the tissue of the cornea, changing the way it focuses on the light to achieve normal vision.
The eyes have always been compared to a camera in the way they process the objects they see. While the retina is responsible for creating the final image, it's the cornea that helps in light focus through bending, a process known as refraction.
When there are irregularities that affect the cornea and it is unable to focus on the light correctly, the image that the retina produces becomes distorted or blurred.
Not all kinds of refractive errors require LASIK as there are some that be corrected with eyeglasses and contact lenses. However, LASIK offers a more comfortable and sometimes, a life-long solution.
LASIK is often compared with RK (radial keratotomy) since both procedures work on the cornea using a laser (although RK can be performed using a knife). However, they are different because RK scrapes the epithelium before reaching the central section of the cornea called the stroma. LASIK, on the other hand, makes a flap.
Who should undergo and expected results
LASIK is recommended for people who suffer from any of the following refractive errors:
- Hyperopia (inability to see near objects properly)
- Myopia (inability to see far objects clearly)
- Astigmatism (blurriness of the image on the retina due to a structural defect of the cornea)
- Presbyopia (inability to see objects clearly due to aging)
Those who are tired of wearing prescription or corrective glasses, as well as contact lenses, may choose LASIK provided that they are in good health.
Before a person can undergo the surgery, screening tests will be performed to ensure that the patient does not have an existing health condition that can affect the results. A good example is diabetes. Retinal neuropathy is a common complication of the disorder in which the nerves of the eyes deteriorate. The disorder can also hinder proper wound healing.
LASIK is performed on patients who are at least 18 years old. Individuals who are engaged in active contact sports may not be considered for the operation.
Certain eye diseases such as dry eyes, thin corneas, large pupils, and inflammation of the eyelids should be seriously considered by the doctor. Otherwise, LASIK can worsen these problems.
Contrary to popular belief, LASIK doesn't result in 20/20 vision at all times. In fact, the success rate for this desired results is only 60%. However, the majority of the patients who have undergone the procedure noticed that their dependence on corrective glasses and contact lenses has significantly decreased following the surgery.
How the procedure works
Lasik uses laser that produces heat to create the flap needed to access the corneal tissue. The laser is also used for changing the shape of the cornea by melting certain parts. In many cases, an IOL (intraocular lens) is added during the surgery to further improve the vision.
To perform LASIK, first, the patient is provided with eye drops to prevent infection and to numb the area. This allows the patient to stay awake and aware during the entire procedure, although some may require mild sedation to increase their level of comfort.
The surgery will be performed one eye at a time. The eye that is not worked on then wears a sterile cover. The eyes should be properly positioned so the laser can accurately target the corneal tissue. Surgical accessories, such as speculum and a suction ring, may be used to keep the eyes open and still throughout the procedure.
A flap is then created using the laser. Another more traditional option is using a surgical blade known as microkeratome. The tissue is then left to dry before another kind of laser called excimer laser is used.
This type of laser is for ablation, which means it destroys or "melts" a part of the cornea called the stroma, eventually changing the shape of this part of the eye. New technologies allow for a more accurate procedure since not only can doctors input the right settings on the machine but can also control the laser to focus on the eyes even if they move.
Overall, it takes less than 15 minutes to complete the surgery for each eye.
Possible risks and complications
One of the first things the patient experiences is a burning sensation, which should go away over time. Moreover, doctors will prescribe medications and steps to take care of the operated eyes while they're still on recovery.
It's rare for LASIK to result in partial or complete vision loss, and this usually happens when the patient doesn't choose a qualified provider.
Other possible complications can be due to incorrect flap procedure and ingrowth in the epithelium and keratoconus, which involves bulging on the surface of the eyes as significant amount of tissue is ablated.
- Garg S, McColgin AZ, Steinert RF. LASIK. In: Tasman W, Jaeger EA, eds. Duane's Clinical Ophthalmology. 2013 ed. Philadelphia, PA: Lippincott, Williams & Wilkins: 2013:vol 6, chap 49.
- Alio JL, Azar DT, Stasi K, Soria FA. Surgical correction of presbyopia. In: Yanoff M, Duker JS, eds. Ophthalmology. 4th ed. St. Louis, MO: Mosby Elsevier; 2013:chap 3.10.
- Yanoff M, Cameron D. Diseases of the visual system. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 431.