Refractive Laser Surgery (Laser Eye Surgery)
Refractive Laser Surgery (Laser Eye Surgery)
What is Refractive Surgery?
If you have a refractive error in your eyes such as Myopia, Hyperopia, or Astigmatism, it is possible to correct these eye defects and improve vision using various surgical techniques, other than glasses or contact lenses. These surgical techniques are collectively referred to as refractive surgery. Nowadays, the most common method for correcting refractive errors or vision problems is using various laser techniques.
The goal is to reshape the transparent, dome-like layer at the front of the eye, called the Cornea, and to correct the eye’s focusing ability. Various laser treatment techniques are used for this purpose. These surgeries can be generally described as correction operations applied to the outer surface of the eye. Other methods involve intraocular procedures, such as lens implantation surgeries.
The most commonly used technique in refractive surgery is LASIK (Laser-Assisted in Situ Keratomileusis). In this procedure, the outer surface of the cornea is reshaped using an Excimer Laser.
In myopic individuals, the cornea is too steep, and refractive surgery techniques flatten the curvature of the cornea, reducing the focusing power of the eye. Thus, in myopia, the image that focuses in front of the retina is corrected and brought directly onto the retina after laser surgery.
In hyperopic individuals, refractive surgery makes the flatter cornea more steeper, increasing the eye’s focusing power. In hyperopic eyes, where the anterior-posterior length is short and the cornea is flat, the image focuses behind the retina. After laser treatment, the image is corrected to focus directly on the retina.
Refractive surgery can also correct Astigmatism. In eyes with astigmatism, certain parts of the irregular cornea are reshaped using lasers, making the cornea more even and symmetrical in different meridians. This way, the light scattering caused by the irregular cornea will be eliminated, and the image will be clear on the retina.
Is Laser Treatment Suitable for Your Eyes?
You should not have any other eye diseases (e.g., Glaucoma, Uveitis, or Diabetic Retinopathy).
You desire to eliminate dependence on glasses or contact lenses.
You must have the appropriate refractive error for this treatment (e.g., Myopia or Astigmatism).
It’s important to know that after this treatment, you might occasionally still need to use glasses or contact lenses to achieve the best visual sharpness.
After undergoing an eye examination and other tests, you should consult your eye doctor to determine the most suitable laser treatment technique for your eyes.
How is the LASIK Technique Applied to the Eye?
LASIK surgery is a simple, painless, and short procedure, and there is no need for the patient to stay in the hospital or receive general anesthesia. It is performed as an outpatient treatment. The patient enters and exits the operating room in about 10-15 minutes. In a sterile environment, the eye is numbed with drops, and an instrument called an eyelid speculum is used to prevent blinking.
After the eye is completely numbed with the drops, the patient will not feel any touch or pain during the operation. The surgery is performed while the patient is lying flat on their back under an Excimer Laser machine in an outpatient treatment unit.
The patient is asked to look at a red fixation light. During the application of the vacuum ring, the patient’s vision may become blurry or dark for a few seconds. This must be explained to the patient beforehand to avoid panic.
The cornea is reshaped by cutting a flap on its outer surface using a microkeratome (a blade or laser), which acts as a hinge. The corneal flap is lifted, and the inner part of the cornea is treated with the Excimer Laser to reshape it. The patient is asked to look at the target light during the shaping process. Afterward, the flap is lowered back into place, and it adheres naturally without the need for stitches. The healing of the flap takes 2-5 minutes.
The procedure for one eye takes about 3 minutes, and the same process is repeated for the other eye.
Post-Operative Recovery Process
After the surgery, the patient should arrange for someone to accompany them home and rest at home, ideally taking a light nap. The patient will be sent home with dark, transparent protective glasses to protect their eyes.
There is no need to cover the eyes with cotton; the goal is to protect the eyes from impact and prevent the patient from rubbing their eyes. Two hours after returning home, the special glasses will be removed, and eye drops will be recommended to prevent the cornea from drying out and to promote healing.
The patient will be able to watch TV and drive the next day. From the second day onwards, the patient can use a computer, digital screens, and mobile phones. The most important factor in the success of this surgery is the patient’s quick recovery and return to their daily routine.
Risks and Side Effects of LASIK Surgery
Like any other surgery, LASIK has some potential risks and complications. Since its approval by the FDA in 1998, LASIK has become a popular treatment option in the USA, and it is also widely used in our country.
The general complication rate is very low, as it is a short correction procedure applied to the outer surface of the eye. As with any other surgical procedure, infection is very rare, and if it occurs, it can be treated quickly with medication.
In some cases, the corneal flap may need to be lifted again for cleaning and washing. Sometimes, a secondary procedure (re-operation) may be needed to achieve the desired vision correction, especially for individuals with high levels of myopia, hyperopia, or astigmatism. This need is more common in patients who require high-degree corrections.
Some patients may experience subjective complaints after LASIK, such as fluctuating blurry vision, difficulty with night vision, burning, dryness, discomfort, and glare. These symptoms generally disappear within 1 to 3 months.
Are You Considering LASIK? Learn More…
Before opting for LASIK treatment, you should fully understand the potential advantages and disadvantages to determine if you are a suitable candidate. You should also discuss with your doctor how your eye’s refractive changes might evolve in the years following the operation and ask any questions you may have to set realistic expectations.
For example, you should discuss with your eye doctor the age range in which this operation will yield the best results, the potential benefits, risks, and how it will impact your quality of life.
Other Refractive Surgery Techniques
Today’s refractive surgery options range from reshaping the cornea with lasers to surgically implanting artificial lenses into the eye. Below are some alternatives to LASIK for refractive surgery:
Wavefront Guided LASIK (Eagle Eye)
In standard LASIK, the refractive error degrees of the patient’s glasses or contact lenses are loaded into the Excimer Laser machine. In contrast, in this technology, Wavefront data is uploaded into the machine.
In Wavefront LASIK, a computer imaging technology creates a highly detailed, three-dimensional map of the patient’s cornea, resembling a miniature topographical surface. This map is then used to guide the laser and correct even the slightest imperfections, offering better correction than standard LASIK.
Many studies show that this technology reduces night vision difficulties and increases the chances of achieving 20/20 or better vision.
PRK Technique (Photorefractive Keratectomy)
PRK is a type of refractive surgery and the first laser treatment technique used. It was widely used before LASIK and is still applied to some cases of thin corneas. The main difference between PRK and LASIK is that in PRK, the corneal flap is not created.
Before laser treatment, the outermost layer of the cornea (epithelium) is removed using a blade. After PRK, the patient may experience significant pain and discomfort for 1-2 days, and bandage contact lenses are used to promote healing.
No-Touch Laser Technique (Trans PRK)
This is a newer form of the PRK technique, where instead of using a blade to remove the epithelium, the laser (Femtosecond) is used to remove the corneal surface. It is typically used for patients with thin corneas. Afterward, soft contact lenses are applied for bandage purposes.
SMILE Laser Technique
SMILE is a new laser procedure developed in recent years as an alternative to LASIK. Approved by the FDA in 2016, the procedure uses Femtosecond Laser to create a small lenticular tissue in the cornea, which is then removed through a tiny incision.
The corneal incision heals within a few days without the need for stitches, and the patient’s vision improves rapidly. The SMILE technique can correct myopia up to -10.00 diopters, and candidates must be at least 22 years old.
SMILE offers a lower risk of dry eye symptoms compared to LASIK due to the lack of a corneal flap.
Requirements for LASIK and PRK Treatment
Conditions Required for LASIK and PRK Treatment
You must be over 18 years old (ideally over 21, as the eye’s growth must be complete).
Your eye prescription should not have increased by more than 0.25 diopters in the last year.
The cornea must be healthy and not cone-shaped.
The cornea should not be too thin.
There should not be advanced dryness in the eyes.
There should be no connective tissue diseases, such as diabetes or rheumatism, in the body.
LASEK
In this method, similar to PRK, no flap is created, and the laser is applied to the surface of the cornea. However, the epithelial layer is loosened with an alcohol solution and separated from the corneal surface, then moved aside, and the laser is applied as in PRK. After the laser treatment, the thin epithelial layer is carefully placed back in its original position. In this method, the patient uses soft contact lenses for bandage purposes for about 4 days.
Epilasik
A special microkeratome, called an epikeratome, is used to separate a very thin epithelial layer from the cornea. This thin layer is moved aside, and the cornea is treated as in PRK. Afterward, the thin layer is placed back onto the corneal surface. In this case, soft lenses may be used for 4 days to act as a bandage to help the epithelial tissue heal.
Conductive Keratoplasty (CK)
CK is a non-invasive thermal refractive surgical procedure used to correct mild to moderate farsightedness (hypermetropia) in individuals over 40 years of age. With CK, instead of a laser, your eye doctor uses a small probe that emits controlled amounts of radiofrequency (RF) energy.
Heat is applied to the peripheral part of the cornea, causing it to shrink slightly like a ring, which increases the steepness of the central cornea. The goal here is to steepen the previously flat central cornea. CK can be used to achieve monovision.
With monovision, CK can be used to improve near vision in a presbyopic eye with good distance vision but poor near focus. Generally, one eye is adjusted for near vision, while the other eye is adjusted to maintain good distance vision. CK does not provide permanent correction, and in some patients, the corrected hypermetropia may reoccur over time.
Intraocular Lenses (Phakic Intraocular Lenses)
Laser treatment can correct myopic vision problems up to -7.00 diopters, but for higher myopic errors (greater than -7.00 diopters), where full correction cannot be achieved with laser, intraocular lens implantation is used as an alternative treatment.
In the Phakic IOL technique, an artificial lens is implanted in the eye in front of the natural lens, without removing the eye’s natural lens. This allows patients to retain their current focusing power. During the Phakic IOL procedure, the eye doctor places the intraocular lens in front of or behind the iris.
Once the IOL is positioned inside the eye, it provides the necessary correction to ensure that light rays fall on the retina with precision.
Refractive Clear Lens Extraction
In refractive clear lens extraction (for correcting refractive errors), an artificial lens is placed in the eye in place of the natural lens to correct vision.
During this procedure, the eye’s natural lens is removed and replaced with an artificial lens, similar to cataract surgery. Although it is an alternative to cataract surgery, refractive lens exchange uses multifocal (multi-focus) intraocular lenses to correct both near and distant vision.
Some patients may prefer this treatment at an early cataract stage instead of waiting for the cataract to develop further. The reason for this is that the lens placed inside the eye at this stage typically provides better vision correction. As a result, refractive clear lens exchange surgery can be a successful option for patients with significant hypermetropia for whom LASIK surgery is not recommended.
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