LASIK, short for “laser-assisted in-situ keratomileusis”, is a corrective eye surgery in which the eye surgeon uses a laser to correct the refractive error of the eye. It is commonly referred to as laser eye surgery or laser vision correction
That simply means Lasik eye surgery corrects the vision disturbances caused by short-sightedness (myopia) or long-sightedness (hyperopia) or astigmatism (a condition where the cornea is oblong instead of spherical).
The main purpose of Lasik is to eradicate the need of wearing glasses or contact lenses and correct your vision. To know how this laser eye surgery works, you should first know what is refractive error and why it gives you those glasses.
What is a refractive error and why do you need to wear glasses?
When the rays of light from an object you are viewing enter the eyes, they pass through the cornea and the eye lens, both being transparent.
To view the object properly, the rays have to be refracted in such a fashion, that they converge to meet on the retina, which is on the posterior wall of the eyeball.
If this does not happen perfectly, then you do not view the object clearly and your vision becomes blurred. Depending on where the light rays meet, in front of the retina or beyond the retina, your eye doctor prescribes the appropriate glasses, so that the refractive error is corrected and the light rays converge to meet exactly on the retina.
Why is Lasik done? Indications
Lasik surgery is indicated in persons with the following vision disturbances.
Myopia (Nearsightedness). You suffer from myopia when your eyeball is longer than normal or when the cornea has a sharper curve. Due to this deformity, the light rays coming from an object, which you are viewing do not converge on the retina but in front of it. Your near vision is clear but you cannot see objects clearly that are far away.
Hyperopia (Farsightedness). When you have a cornea shorter than normal or the curve of the cornea is flatter than normal, the light rays coming from an object you are viewing focus behind the retina instead of on it. Your near vision suffers but your far vision is clear.
Astigmatism. Astigmatism is a vision problem caused by an error in the shape or curve of the cornea. This disturbs the focusing of the light rays from near as well as distant objects on the retina. You are unable to see near and far away objects clearly.
If you are associated with any of the above eye problems, you are already wearing glasses for the correction of your sight. After considering the pro and cons, your eye doctor will tell you if you should undergo Lasik eye surgery or not.
Benefits of Lasik
Generally, most people who undergo Lasik eye surgery achieve 20/20 vision or better, which works well for most activities.
Lasik eye surgery improves your vision almost immediately without the bother of using eyeglasses. It helps to achieve 20/20 vision or more after the refractive surgery.
Studies indicate that almost 80 percent of the people who undergo Lasik do not have to wear glasses or contact lenses after surgery for most of their routine activities.
Around 96% of patients get their desired vision level after this surgical procedure
The surgery is painless due to the local anesthetic eye drops used.
You will see successful results almost immediately or max on the day after.
No sutures or bandages are required after the surgery.
You can get your age-related vision changes such as presbyopia corrected even years after the surgery.
How does Lasik surgery work?
The principle of Lasik surgery is to alter the incorrect shape of the cornea of the eye to the desired contour so that the newly acquired shape helps to refract the rays of light in the right manner onto the retina and the need for glasses is abolished.
The eye surgeon performs the surgery using a computer, which, with the help of software, analyses the shape of the cornea and determines the necessary corrective changes to be incorporated into its shape.
The surgeon uses a highly specialized laser called the excimer laser, which emits a very concentrated light and operates as per the feed from the computer. A highly skilled Lasik eye surgeon performs this surgery. Both eyes can be operated on at the same time.
Preoperative procedure
The eye surgeon performs a general check-up of the eye to rule out any other eye pathology.
He examines the cornea and measures its thickness with the help of an instrument called the pachymeter.
With low-grade lasers, he determines the topography of the cornea and maps it out. This will also help to rule out astigmatism.
Eye analysis is also done using the new wavefront technology, which gives more detailed and exact information about your eye defects. These details of the cornea are necessary as it is the cornea, which is operated upon in LASIK surgery. With the help of these details, the eye surgeon is able to calculate and determine from where and how much of the corneal tissue should be removed. The wavefront-guided LASIK gives better results.
The surgeon prescribes systemic and local antibiotics to the patient preoperatively.
If the patient wears soft contact lenses, he is advised to stop wearing those 2 to 3 weeks before the surgery. If the patient wears hard contact lenses, he will be asked to stop wearing those for a longer period prior to surgery.
Lasik surgery procedure
During the LASIK operation, the patient is awake. He is given a mild sedative and local anesthetic drops are instilled into the eyes.
The whole procedure does not take more than 15 minutes though the actual laser procedure takes less than 5 minutes.
First Step – creating a flap in the cornea. The surgeon makes a partial incision in the cornea either manually with the help of a microkeratome, (a high-precision surgical blade) or with the help of a laser microkeratome. He creates a flap in the outer layer of the cornea. He folds the flap back to reveal the middle layer of the cornea called the stroma. This flap folding requires precision and skill.
Second Step – Using the laser. The computer-controlled excimer laser is used to vaporize the pre-calculated amount of corneal stroma from the pre-determined part of the corneal stroma. The laser is very precise up to tens of micrometers in thickness. This laser ablation is so fine and accurate that it does not damage any adjacent stroma tissue. There is no pain and quick visual recovery results because of this and it is in these advantages, that Lasik scores over the earlier followed PRK (photorefractive keratectomy) procedure.
Third Step. The surgeon then carefully repositions the corneal flap back to its original position to heal on its own. No stitches are necessary.
Postoperative care
Follow up regularly with your eye surgeon for six months.
The patient continues the use of systemic and local antibiotics eye drops to avoid infection from setting in.
The patient should stay indoors and sleep as much as possible.
The patient should wear dark glasses even during sleep to avoid rubbing of eyes.
The patient can resume outdoor activity only after the eye surgeon permits.
Recovery
Though complete recovery after Lasik may take a few weeks, your functional vision improves within 4 to 6 hours after surgery. However, some patients may experience blurred vision for a few days after surgery, which later clears up.
Patients are advised to attend work after two or three weeks though some patients feel it fit enough to attend the next day.
Lasik is a one-time permanent treatment. However, as you cross 40 years of age, you may require reading glasses due to age-related changes in vision.
Risks and complications
As with every surgery, Lasik eye surgery too has its share of complications and risks. The risk of surgery is very low, but it does exist.
You can minimize the risk of complications by choosing a Lasik eye clinic and surgeon with discretion.
You should look for the experience of the eye surgeon and the availability of the latest equipment. This will reduce the chances of any surgery side effects.
Complications that can occur post-Lasik include:
Dry eyes. This is a common problem of Lasik eye surgery and is seen in 1/3rd of the operated patients. Dry eyes are accompanied by dryness of the eyes, itching, and pain. A sense of a foreign body in the eye is felt. If not treated, it becomes chronic and results in chronic pain and visual impairment. Dry eyes are treated with topical artificial tears and punctual occlusion, wherein the natural drainage of the eyes is blocked by plugging it with collagen.
Infection. The onset of infection is characterized by redness of the eyes, pain, and oozing. This infection present post-operatively is treated with topical eye drops and oral antibiotics.
Overcorrection or under-correction. The refractive error may get overcorrected or undercorrected. This leads to blurring of vision, which has to be corrected by glasses or contact lenses.
Visual Acuity. Clearness of vision keeps on varying.
Halos or stars are seen around sources of light at night.
Double vision, also called diplopia may occur. Treatment includes prism lenses, vision therapy, and/or corrective surgery.
Remnants of stromal debris may remain under the closed flap of the cornea. This has to be removed surgically.
Astigmatism (conical and improper shaping of the cornea) may result due to Lasik surgery.
Refractive power variation may occur in both eyes. This is corrected with glasses or contact lenses.
“Sands of Sahara” is the post-operative collection of inflammatory cells and white blood cells under the closed corneal flap. This does not allow the corneal flap to heal and can result in loss of vision. Antibiotics and local eye drops are given and by a small corrective surgery, these cells are removed.
Improper aligning of the corneal flap during surgery can result in micro folds or wrinkles of the corneal flap. This is seen in less than 5% of the patients. Here the stats vary from surgeon to surgeon. This complication results in astigmatism. Another corrective laser surgery is required.
Subconjunctival hemorrhage may occur and conservative treatment in the form of local eye drops is then prescribed.
The chances of most of these risks of Lasik eye surgery can be minimized by choosing the right Lasik eye surgeon and the Lasik center.
