Refractive Surgery refers to any surgical procedure used to fix vision problems. It is also known as Vision correction surgery or laser eye surgery. Refractive and laser eye surgery allow patients to get back their 6 by 6 vision.
If you have any refractive error, such as Myopia (nearsightedness), Hyperopia (farsightedness), Astigmatism or Presbyopia, Refractive Surgery is the method for correcting or improving your vision. Basically performed for specs removal.
It is important to understand how normal vision happens first, to know how the anatomy of the eye works. To better understand how refractive errors affect our vision. Those who have normal vision, below is how we see things:
- Light enters the eye through the cornea, the clear layer at the front of the eye.
- From the cornea, the light passes through the pupil. The amouin of light crossing through is controlled by the iris, the colored part of the eye.
- Now the light hits the lens, the transparent structure inside the eye that focuses light rays onto the retina.
- Next, it moves through the vitreous humor. This is a clear, jelly-like matter that fills the center of the eye and helps to keep the eye rounded shape.
- Finally, it arrives at the retina. This lines the back of the eye. The light-sensitive nerve layer where the image is inverted.
- The optic nerve, then, sends this information to the brain. The brain converts the impulses it receives into images.
Refractive surgery is required to correct errors that happen when the shape of the eye prevents light from focusing directly on the retina.
Below are the common refractive errors. These errors affect vision & eyesight and may need corrective lenses or surgery for correction or improvement.
Types of Refractive Errors
The Refractive Errors are usually addressed through prescription eyeglasses or lenses. Refractive surgery treats these conditions and eliminates or reduces the need to use glasses or lenses.
Nearsightedness is a common eye disease, in which the image of a distant object becomes focused ahead of the retina, instead of on it. It happens either because the refractive power of the eye is too strong, or because the eyeball axis is too long. It makes distant objects appear blurry and out of focus.
This condition may cause headaches and/or eye strain.
Eyeglasses or contact lenses are prescribed to help correct or improve myopia by adjusting the focusing power to the retina.
For the patient, correct refractive surgery may also help by changing the shape of the cornea to a more spherical, round shape instead of an oblong shape. By reducing the curvature of a cornea that is excessively steep. This way the eye’s focusing power is reduced. Images that are focused ahead of the retina, due to this steep corneal curve, are pushed closer to or directly onto the retina with the refractive surgery.
Commonly known as farsightedness, hyperopia is the opposite of myopia. It is also a common refractive error in which an image of a distant object becomes focused beyond the retina. Making close objects appear out of focus. This happens either because the refractive power of the eye is too weak, or because the eyeball axis is too short.
It may cause headaches and/or strain in the eyes.
Eyeglasses or contact lenses help to correct or improve farsightedness by adjusting the focusing power to the retina.
People with Hyperopia will have refractive surgery that makes the cornea steeper and to increase the eye’s focusing power. Images that are focused behind the retina, due to a short eye or flat cornea, will be drawn closer to or directly onto the retina after surgery.
Presbyopia is another type of farsightedness. It is caused when the center of the eye lens hardens. This makes it unable to see nearby objects clearly. This is typically an age-related condition, eventually affecting almost everyone from 35-40 onwards. It may even affect patients who have myopia.
Eyeglasses or contact lenses may be prescribed to correct or improve the condition.
Astigmatism is when objects up close and at a distance appear blurry. It is caused by an abnormal curvature of the cornea that makes two focal points to fall in two different locations.
Astigmatism may cause eye strain and may be combined with myopia or hyperopia.
Eyeglasses and contact lenses may help to correct or improve health.
It can also be corrected with refractive surgery using techniques that reshape selected parts of an irregular cornea to make it smooth and symmetrical. With the result that images focus clearly on the retina instead of being distorted due to light scattering through an irregularly shaped cornea.
Types of Refractive Surgery
There are several surgical procedures for correcting or adjusting the focusing ability of the eye by reshaping the cornea. There have been huge advances in recent years in this field.
Most types of vision correction surgery reshape the cornea. This lets light travel through it and focus properly on the retina. Other procedures replace the natural lens of the eye and an artificial one is implanted.
The most popularly performed type of refractive surgery is LASIK (Laser-Assisted In situ Keratomileuses) surgery, where laser beams are used to reshape the cornea.
LASIK, or laser in-situ keratomileusis, works for people who have Myopia, Hyperopia or Astigmatism.
The best Eye Doctor Delhi will reshape the underlying corneal tissue to focus light into the eye and reach the retina. In the surgery, a flap will be made in the outer layer of the cornea to get to the tissue underneath. She will, then, reshape the tissue underneath your cornea, by using laser beams.
What makes LASIK surgery differ from other procedures is its methodology. of creating a flap of the outside layer of the cornea to access the underlying tissue. The surgery requires precision, calmness, and focus. Various advancements in computer imaging wavefront technology allow LASIK specialists to generate detailed images of the cornea and guide the treatment.
PRK (Photorefractive Keratectomy)
PRK is a procedure that uses a laser to sculpt the surface of the cornea. It’s ideal for correcting mild to moderate nearsightedness, farsightedness, or astigmatism. PRK can also work with computer imaging technology.
Unlike LASIK, PRK only affects the surface of the cornea, not the tissue underneath.
Your doctor may also use computer imaging of the cornea.
Before the laser can do its work, a blunt microkeratome is used to remove the epithelial layer of the cornea.
Nowadays an advanced technique has evolved, known as Surface Ablation. It cools the cornea before and after the surgery to reduce the discomfort the patient may experience. You may be given a special contact lens to act as a bandage to facilitate the healing of the epithelial layer. The healing usually takes around 4 days. Antibiotics, anti-inflammatory medication, as well as pain killers, may also be prescribed.
LASEK (Laser Epithelial Keratomileusis)
This surgery is a slight variation of PRK.
Your Eye Doctor will create a flap. Under LASEK a trephine blade is used, which is much finer than the one used in LASIK, to make the flap. An alcohol solution is used to loosen and lift the epithelial cells. After this, an excimer laser sculpts the cornea through ablation. And the flap is set and secured with a soft contact lens so that it can heal.
The complete process takes about 15 minutes for one eye. The recovery takes around 4-7 days. Vision improves within 6-8 weeks.
LASEK treats nearsightedness, farsightedness, and astigmatism. LASEK is a great choice for people who have less corneal tissue. When compared to LASIK, LASEK poses less risk of causing Dry Eyes and causes no stromal trauma.
Phakic Intraocular Lens Implants
Phakic intraocular lens implants are designed for patients who are too nearsighted for PRK or LASIK.
For this surgery, the doctor makes a small incision at the edge of the cornea, first. Then she would either attach the implant lens to your iris or insert it behind your pupil. Unlike RLE, the natural lens of the eye is left in place.
Visian ICL is the main type of phakic lens implant used.
Limbal Relaxing Incisions (LRI)
Limbal relaxing incisions are made on the cornea to treat astigmatism.
When you have astigmatism, the eye protrudes, like a football, instead of being round. Astigmatism is caused by corneas that are either too elongated in one axis and too flat in another. The doctor makes one or two incisions at the steepest part of the cornea. Or the Limbus, the junction between the sclera and the cornea. This helps it deflate and makes it more rounded.
The procedure required very precise planning on where the cuts will be made. It doesn’t use lasers. Despite all that, the procedure is rather painless and eliminates the need for distance glasses.
This procedure can be done as a standalone, or with other laser eye surgeries like PRK, LASIK, or RK.
RLE (Refractive Lens Exchange)
Other names include Clear Lens Exchange or Extraction (CLE), and refractive lens replacement (RLR).
The procedure in this refractive surgery is the same as cataract surgery. The doctor makes a small incision at the edge of the cornea. She, then, removes your natural lens and replaces it with an artificial lens implant.
This surgery can correct severe farsightedness or nearsightedness. It is ideal for people who have thin corneas, dry eyes, or other minor cornea problems. RLE can be undertaken along with a LASIK or LASIK-related procedure to correct astigmatism.
PRELEX (Presbyopic Lens Exchange)
This refractive surgery is performed on patients with presbyopia. Presbyopia, as explained above in the blog, is when the eye’s lens loses its flexibility. Patients with presbyopia have difficulty focusing on close objects, such as reading or threading a needle. PRELEX is a method where the Eye Doctor implants a multifocal lens to improve flexibility and recover focus.
ICR (Intracorneal Ring Segments)
It is also known as Intacs. The doctor cuts a small incision in the cornea and plants two crescent-shaped plastic rings at the outer edge. The rings help to flatten the cornea and change the way light rays focus on it. ICR was, earlier, used to treat nearsightedness, but has been replaced by the advanced laser-based procedures. Now it’s used to treat keratoconus, a condition of an irregular-shaped cornea that causes the cornea to thin-out and results in vision loss.
Radial keratotomy (RK)
Radial keratotomy surgery is performed to improve or remove nearsightedness. This is done by making small incisions in the cornea to flatten it. If you also have astigmatism, you may need more incisions.
The surgery can take between 10 to 15 minutes, per eye. But generally, the other eye is operated after waiting for around 6-weeks, to prevent infection and strain. Recovery will take a few days. Meanwhile, you may have to make frequent visits to the surgeon after the surgery.
With recent advances in refractive surgery, such as LASEK and PRK, RK is not much common now. Among patients as well as Ophthalmologists.
ALK (Automated Lamellar Keratoplasty)
ALK can help people with extreme nearsightedness and some farsightedness. For this procedure, the Eye Doctor creates a flap in the cornea to access the underlying tissue. She will make an incision in the sub-layer of the cornea to reshape and correct vision.
No laser is used.
However, nowadays, LASIK has all but replaced ALK as a method of correction.
The good results of the above listed refractive surgeries are well-researched and documented. But like all surgeries, there can be some side effects. It’s essential to keep them in mind.
Infection and delayed healing: Some people may get infected after PRK or LASIK. It generally means a longer healing process and added discomfort.
Under-correction or Over-correction: You may still need glasses or contacts after the surgery. There is no way to assess how well the surgery worked until the eye has healed suitably. If your eyesight and vision haven’t improved much, a second laser surgery, called laser enhancement, can help.
Worse vision. It’s quite rare, but the vision for some people gets worse than before the surgery. Excess corneal haze or irregular tissue removal are the usual culprits.
Excess corneal haze: This can be a part of the natural healing after PRK surgery. It can only be seen through an eye examination. It usually has no effect on the vision. If it does affect your vision, you may need a second procedure. Also, a medicine called mitomycin C (MMC) during PRK surgery has proved effective in its prevention.
Regression: Sometimes the effects of surgery go away over a period of few months after healing. A second surgery may be required to improve your vision.
Halo effect: This may occur in dim light and can make it hard to drive or see in dark places. As your pupil opens, the untreated area outside of the cornea produces a second image. It can happen after LASIK or PRK surgery. Your Eye Doctor can use laser optical zones or wavefront technology, which creates a 3-D version of your eye so that the surgery is more precise, to make it less likely. Severe cases of nearsightedness treated with LASIK and PRK increase the halo risk, while Visian ICL for higher nearsightedness has less halo risk.
Damage on Flap: A hinged flap is created under LASIK on the center of your cornea. It may need to be repositioned within the first few days following the surgery or after a severe direct eye injury.
Refractive surgery has evolved beyond simple laser refractive techniques over the past few years. Laser refractive surgery procedures (such as LASIK), surface ablation techniques (such as LASEK or laser epithelial keratomileusis), and PRK (photorefractive keratectomy) is now established as safe and convenient procedures that produce excellent visual outcomes for patients with low-to-moderate amounts of Refractive Errors. Additionally, a wide variety of options is now available to treat the extensive range of these errors.
Small Incision Lenticule Extraction (SMILE) uses a femtosecond laser to shape a refractive Lenticule, which is removed through a small wound. The advantages of this procedure include better tectonic strength and less dry eye. In the coming days, intracorneal (ICL) implants could be used to treat hyperopia or presbyopia.
Thus, eye surgeons have now quite good options to provide patients with the appropriate refractive correction based on their condition.
There is no best method for correcting refractive errors, that has been universally accepted. The best option for you should be decided and discussed after a thorough examination with your Eye Doctor.
If you are considering refractive surgery, consult EyeMantra Now. There you can discuss your lifestyle and vision to determine the most appropriate procedure for you.
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