Corneal Refractive Surgery (Both Eyes)

Overview

Refractive surgery is a way for repairing or enhancing your eyesight if you have a refractive defect such as nearsightedness (myopia), farsightedness (hyperopia), astigmatism, or presbyopia. There are several surgical methods for reshaping the cornea, or transparent, circular dome at the front of the eye, to repair or alter your eye's focusing capacity. Other treatments include inserting a lens into your eye. LASIK (laser-assisted in situ keratomileusis) is the most common type of refractive surgery, in which a laser is used to reshape the cornea.

Certain refractive surgical treatments for nearsighted persons will minimize the curvature of a too steep cornea, reducing the eye's focusing capacity. Following surgery, images that are concentrated in front of the retina due to a longer eye or a sharp corneal curvature are pushed closer to or directly onto the retina.

Farsighted persons will have refractive surgery to obtain a steeper cornea, which will boost the eye's focusing capacity. Images that are focused beyond the retina as a result of a short eye or a flat cornea will be brought closer to or directly onto the retina following surgery.

Refractive surgical procedures that carefully reshape portions of an irregular cornea to make it smooth and symmetrical can treat astigmatism. As a result, instead of being distorted by light scattering through an unevenly shaped cornea, images concentrate clearly on the retina.

What are Refractive Errors?

The quality of your eyesight is determined by how well your cornea and lens concentrate light rays on the retina. To concentrate on the retina, light rays must bend (refract). The retina is a light-sensitive nerve layer located in the back of the eye. It generates impulses from light rays that are sent to the brain via the optic nerve.

Refractive errors are visual abnormalities produced mostly by an irregularly formed cornea or an eye that is longer or shorter than usual. The cornea is the transparent component of the eye at the front. Light waves are curved and focused by it. Light from an object is not focused on the retina due to refractive flaws. This results in a fuzzy image. In otherwise healthy eyes, refractive defects can arise.

There are 4 types of refractive errors:

• Nearsightedness (myopia). Close things seem sharp. However, objects in the distant seem hazy. From front to back, the eye is longer than usual. Or the cornea is too curved. Images are focused in front of the retina rather than on it.
• Farsightedness (hyperopia). You can plainly see distant objects. However, nearer items are obscured. The eye is smaller than usual. Alternatively, the cornea is too flat. Images are concentrated behind the retina.
• Astigmatism. At any distance, objects are blurred. The cornea, lens, or both are formed in such a way that pictures are not precisely focused on the retina. Refractive surgery can’t correct this problem. Surgery can make distance vision clearer. But it may make near vision worse.  

Getting Ready for Corneal Refractive Surgery

Even though LASIK is a relatively safe technique, because seeing is so vital, some apprehension is typical before surgery. Knowing how to prepare for your operation in the weeks and days leading up to it can make you feel more at ease and boost your chances of a positive outcome.

• Location

LASIK surgery is performed at an outpatient surgical clinic or in your ophthalmologist's clinic under local anesthesia.

Your eye doctor will tell you to come approximately an hour early for your appointment. Arriving early allows you to complete any essential papers and rest a little before the treatment.

When you are ready, you will be led into the procedure room and seated on a reclining chair. A laser system, consisting of a huge machine, a microscope, and a computer screen, will be located next to you.

• What to Wear?

On the day of your operation, wear loose-fitting, casual clothing that does not need to be pulled over your head. You'll want to be as comfortable as possible during the treatment and prevent having to change when you get home.

Wearing hair accessories can also interfere with how the surgeon sets your head beneath the laser.

Avoid applying or using the following items before to your procedure to prevent dirt or chemicals from getting into your eyes:

1. Make-up, especially eye makeup (remove the night before surgery).
2. Perfume or cologne.
3. Eye or body lotion or creams.
4. Clothing that has loose fibers or animal hair from a pet that may shed.
   

• Food and Drink

On the day of surgery, you should eat a light meal before leaving for your appointment. You do not need to fast.

You can drink water and other fluids, but avoid alcohol.

• Medications

There are few exceptions, but most people can continue to take their prescribed prescriptions as usual.

The following medications may need to be discontinued around the time of surgery:

1. Certain migraine drugs, such as Imitrex (sumatriptan), might impair corneal wound healing.
2. Accutane, a medicine used to treat severe cystic acne, can cause eye dryness.
3. Antihistamines available over the counter, which can cause eye dryness.

Furthermore, if you take a prescription that makes you drowsy or sleepy, your doctor may instruct you to forgo a dosage on the day of your surgery.

• What to Bring?

You must bring a few essential items to your LASIK surgery visit. These are some examples:

• A credit card or other form of payment that is due on the day of (or occasionally before) your surgery.
• Although LASIK is not often covered by insurance since it is considered an elective operation.
• A case for your spectacles (you'll use the doctor-provided sunglasses at home).
• Make an arrangement to have someone drive you home following the surgery. The procedure itself normally takes 20 to 30 minutes, but you should plan to be in the clinic for around 90 minutes in total. 

There should be no problem with that individual waiting in the waiting area while you are undergoing surgery.

It's also a good idea to plan ahead of time for that person, or someone else, to remain with you and assist you for a few hours while you relax at home. For example, your eyesight may be too fuzzy for you to make a meal or drive safely.

• Pre-Op Lifestyle Changes

Prior to your procedure, your surgeon may advise you on the following steps to improve the safety and quality of the surgery:

• Discontinue contact lenses for one to two weeks (before to preoperative consultation and surgery) for soft lenses and three to four weeks for hard lenses.
• Make plans to take at least one to three days off from work; this may be extended if you work under particular conditions (e.g., within a dusty environment or if you work with power tools).
• To help avoid infection, thoroughly clean your eyes and eyelids before surgery.
• Reduce your alcohol and/or smoking use, since excessive usage might impair recovery following LASIK eye surgery.

Types of Corneal Refractive Surgery

Types of surgery to correct refractive errors include:

• LASIK (laser in-situ keratomileusis).
• Photorefractive keratectomy (PRK).
• Radial keratotomy (RK).
• Astigmatic keratotomy (AK).
• Automated lamellar keratoplasty (ALK).
• Laser thermal keratoplasty (LTK).
• Conductive keratoplasty (CK).
• Intracorneal ring (Intacs). 

LASIK

This procedure is used to rectify myopia, hyperopia, or astigmatism. An excimer laser is used to reshape the cornea during the process. Many previous refractive eye surgery approaches have been supplanted by LASIK.

A computer-controlled excimer cold laser is used for this procedure. It also makes use of a microkeratome or a femtosecond laser. The surgeon uses one of these tools to cut a flap in the middle of the cornea. The excimer laser is used to remove a thin layer of tissue. This causes the cornea to flatten. The flap is replaced without the use of stitches. It quickly reattaches to the cornea.

Wavefront-guided LASIK is a complex technique for assessing optical distortions in the eye. The technology may be used to assess the eye prior to surgery. It determines how light is distorted when it enters the eye and is reflected back. This produces an optical map of the eye and identifies trouble regions. A LASIK surgeon can use wavefront technology to fine-tune the laser beam settings for a more accurate operation. This can improve eyesight and lessen issues with night vision.

In most circumstances, healing following LASIK surgery is painless and quick. 

Possible complications include:

• Overcorrected or undercorrected vision.
• Irregular astigmatism.
• Corneal haze or glare.
• Sensitivity to light.
• Inability to wear contact lenses.
• Loss of the corneal flap and need for a corneal graft.
• Scarring.
• Infection.
• Blurry vision or vision loss.

Photorefractive keratectomy (PRK)

This operation is performed using the same excimer laser as is used for LASIK. PRK is a procedure used to reshape the cornea in order to address mild to moderate nearsightedness (myopia).

By removing microscopic amounts of tissue from the cornea's outer surface, the excimer laser beam reshapes it. A computer is used to map the surface of the eye during the operation. It also computes how much tissue should be removed. This procedure usually just takes a few minutes. Because the corneal surface is removed, healing takes a few weeks.

The most common side effects include:

• Eye pain that may last for several weeks.
• Mild corneal haze right after surgery.
• Glare or halos around lights for months after surgery. 

Radial keratotomy (RK)

This method is used to treat mild myopia. A diamond scalpel is used to make tiny cuts (incisions) in the cornea. The incisions flatten the cornea's center and alter its curve. This lowers refraction. Because the cornea has been cut, healing takes a few weeks. This procedure was quite prevalent. However, LASIK has practically replaced it.

Possible complications include:

• Changing vision during the first few months.
• Infection.
• Discomfort.
• A weakened cornea that can rupture.
• Trouble fitting contact lenses.
• Glare around the lights.
• Clouding of the lens (cataract).
• Vision loss.

Astigmatic keratotomy (AK)

Astigmatic keratotomy (AK) is quite comparable to radial keratotomy (RK). Astigmatism is treated with this operation. Instead of creating radial incisions, the eye surgeon makes curved cuts in the cornea.

Automated lamellar keratoplasty (ALK)

This is used to treat hyperopia and severe myopia. To correct myopia, the eye surgeon uses a special blade to cut a flap across the front of the cornea (microkeratome). The flap has been pushed to the side. A tiny slice of tissue is taken from the cornea's surface. This lowers refraction by flattening the center cornea. The flap is then replaced. The flap reattaches without the need of stitches.

During ALK for hyperopia, the eye surgeon uses a microkeratome to make a deeper cut into the cornea to create a flap. The corneal surface stretches and bulges as a result of the pressure in the eye. The bulging cornea enhances optical power. This reduces hyperopia. The flap is then replaced. It can be reattached without sutures.

Possible complications of ALK surgery include:

• Overcorrected or undercorrected vision.
• Astigmatism.
• Inability to wear contact lenses.
• Loss of the corneal flap and need for a corneal graft.
• Scarring.
• Infection.
• Vision loss.
• Glare.

Laser thermal keratoplasty (LTK)

A laser is used to provide heat to the cornea's margins in this approach. This causes the collagen fibers to contract and the cornea to reshape. This operation is only available to people over the age of 40.

Conductive keratoplasty (CK)

This procedure corrects mild to moderate hyperopia. It reduces the collagen and changes the curvature of the cornea by using heat from low-level radio waves. The radio waves are applied to the outer cornea with a probe little larger than a strand of hair. This results in a tight band. The band enhances eyesight by increasing the curvature of the cornea. This operation is only available to people over the age of 40.

What Makes a LASIK Best Choice?

LASIK is the most common type of refractive eye surgery. Benefits of LASIK include:

• Less pain and faster recovery.
• It can correct a wide range of myopia.
• It can be repeated to correct vision further.
• The eye is not weakened, because only 1 flap is cut into the cornea.
• Little or no scarring of the cornea. 

But other types of surgery may be more suitable for your needs. And refractive eye surgery is not an option for everyone. Talk with your eye care provider about your type of vision problem, and if surgery may be right for you.

Corneal Refractive Surgery Alternatives

Today's refractive surgery options for vision correction vary from laser-assisted corneal reshaping to surgical intervention of artificial lenses. The following are some alternatives to LASIK refractive surgical procedures.

1. EpiLasik

The Epi-keratome is a specialized microkeratome that is used to carefully detach a very thin sheet of epithelial tissue from the cornea. This thin film is pulled to the side, and the cornea is treated in the same way as PRK is. The thin film can then be repositioned to re-adhere to the cornea or removed. A "bandage" soft contact lens is placed and maintained for four days to aid in the healing of the epithelial layer.

2. Phakic Intraocular Lenses (IOLs)

Phakic IOLs are designed for patients who have severe refractive defects that cannot be safely corrected by corneal-based refractive surgery. The phakic IOL, also known as an implantable contact lens (ICL), is surgically inserted into the eye in front of the normal lens. Because the natural lens of the eye is not removed, patients retain their ability to focus.

Your ophthalmologist will insert the phakic IOL either in front of or behind the iris of the eye during the phakic IOL operation. Once within the eye, the IOL offers the required correction to precisely redirect light beams onto the retina.

3. Refractive Lens Exchange (Clear Lens Extraction)

To enhance eyesight, refractive lens exchange (RLE), also known as Clear Lens Extraction (CLE), uses an artificial lens to replace your eye's natural lens. The process is similar to cataract surgery.

RLE, like cataract surgery, may use multifocal or accommodating intraocular lenses (IOLs). These glasses enable you to focus at any distance.

Some persons with early stage cataracts may elect to get RLE rather than wait for their cataracts to develop to the point where they need to be removed. This is due to the fact that lens implants often offer people with improved uncorrected vision at that stage, especially if they require vision correction.

RLE may potentially be an option for those who have severe hyperopia (farsightedness) who are not candidates for LASIK.

Although RLE is not FDA-approved, ophthalmologists may legally perform it in what is known as a "off-label" application.

How Long Does It Take to Heal After The Surgery?

One advantage of using laser surgery to treat refractive problems is that recovery time is usually short.

Your eye begins to recover immediately after LASIK, or other comparable procedures that create a replaceable flap in your cornea. Your eye surgeon or another eye specialist will test your eyesight and make sure your eyes are healing properly the day following surgery. In most circumstances, you will be able to return to work and drive the next day

Healing may take a bit longer if you have undergone PRK. This is due to the removal of a thin, outer layer of corneal cells (rather than replaced as a flap like with LASIK). The cells recover, however it takes a few days following surgery. This will increase the length of time it takes to return to work and driving comfortably and safely.

It is typical to experience some hazy vision or see your eyesight changing for several weeks or even months following laser eye surgery. You may also experience dry eyes, glare, or halos around lights.

You will most likely be scheduled for regular follow-up appointments with your eye doctor for six months or more after laser surgery to check on how your eyes are doing. Most patients' eyesight is steady and clear six months following surgery. If you have dry eyes or other visual abnormalities following surgery, you should notice that most of these symptoms have gone away or have become considerably less noticeable.

If you still have vision problems six months following laser eye surgery, your ophthalmologist may propose another laser surgery operation called an enhancement to fine-tune your eyesight.

Corneal Refractive Surgery Complications

LASIK (laser eye surgery for vision correction) has risks, just like any other procedure. According to research, significant problems are uncommon, and the vast majority of patients are pleased with the outcome. However, anybody considering elective surgery should speak with their ophthalmologist about the risks, results, and reasonable expectations.

Several suicides have been connected in news publications to LASIK problems. While these experiences are distressing, they may make conclusions that aren't totally supported and propose trends that aren't backed by research or clinical reports.

In the 20 years after the operation was authorized by the US Food and Drug Administration, the hazards of LASIK have been carefully researched. More than 300 peer-reviewed studies have found that, on average, 95 percent of LASIK patients were happy with their results.

It's also true that a small percentage of LASIK patients have serious, long-term negative effects.

Temporary adverse effects may include:

• Cloudy or blurry vision.
• Problems with night vision and/or driving at night.
• Scratchiness, dryness, and other dry eye symptoms.
• Bright glare, halos, or starbursts.
• Sensitivity to light.
• Unhappiness or pain.
• Pink or red spots on the white of the eye.

In a small number of patients, some of these effects may be permanent.

Conclusion

When it comes to vision correction surgery, many people instantly think of LASIK (laser-assisted in situ keratomileusis). This recognized technique is a form of corneal refractive surgery - a laser process that modifies the curvature of the cornea and how light reflects onto the retina, therefore improving vision.

Although LASIK is extremely successful, not every patient is an excellent candidate for the operation. However, there are a number of corneal refractive operations available in addition to LASIK to treat a variety of visual disorders such as astigmatism, nearsightedness (myopia), and farsightedness (hyperopia).