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What Is Refractive Surgery?
Refractive surgery is a procedure that corrects common vision problems resulting from refractive errors. Refractive errors occur when your eyes cannot focus images accurately onto the retina, which is the sensory tissue lining the back of your eye. As a result, refractive errors cause blurry vision.
Types of refractive errors include:
- Myopia (nearsightedness)
- Hyperopia (farsightedness)
- Presbyopia (age-related farsightedness)
Types of Refractive Surgeries
There are several forms of refractive surgeries. Although LASIK (laser in-situ keratomileusis) is one of the most popular options, not everyone is a candidate. Your ophthalmologist can determine which surgery is the best choice for you.
LASIK (laser in-situ keratomileusis)
LASIK eye surgery corrects your vision by reshaping the clear surface of your eye, called the cornea. The surgeon uses either a femtosecond laser or microkeratome blade to create a flap on your cornea.
Once the flap is lifted, an excimer laser reshapes the corneal tissue underneath. If you are nearsighted, the laser flattens the curvature of your cornea to reduce your eye’s focusing power. If you are farsighted, the laser steepens your cornea to increase focusing power. For those with astigmatism, LASIK evens out the irregular shape of your cornea so that it is more symmetric. After this step, the flap is replaced, which acts as a bandage to reduce recovery time.
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There are custom LASIK procedures that deliver more precise and personalized visual results, including wavefront-guided, wavefront-optimized, and topography-guided LASIK.
PRK (photorefractive keratectomy)
PRK is also performed with a laser, but unlike LASIK, the surgeon does not create a corneal flap. Instead, the surgeon applies an alcohol solution or uses surgical instruments to remove the cornea's outer layer (epithelium). Then, the surgeon applies the excimer laser to reshape your cornea. Because there is no flap, the surgeon applies a bandage contact lens, which protects your eye as the epithelium heals.
The healing time is also longer than LASIK. With LASIK, some people go back to work the next day. With PRK, many people choose to take a week off work to recover.
LASEK (laser subepithelial keratomileusis) and Epi-LASIK
LASEK includes a combination of LASIK and PRK techniques. An alcohol solution loosens the epithelium, but instead of removing the tissue, the surgeon creates a flap in the epithelium. This flap is thinner than the one created during LASIK, making this a suitable choice for thin corneas.
Epi-LASIK also creates a thin epithelial flap with a microkeratome blade. This procedure does not involve using an alcohol solution, so it is less damaging to the cornea than LASEK.
SMILE (small incision lenticule extraction)
SMILE primarily corrects myopia and some astigmatism. SMILE uses a femtosecond laser to create a circular piece of tissue in the inner layer of your cornea, called a lenticule. Then, the surgeon creates a small incision on your cornea and removes the lenticule through this incision.
Although this is a newer procedure, some studies show that SMILE is a promising alternative to LASIK. Benefits include less dry eye and a more stable corneal structure after surgery.
RLE (refractive lens exchange surgery)
RLE is similar to cataract surgery, only it is performed before one develops a cataract, which is a clouding of the natural lens inside the eye. During the procedure, the surgeon removes your natural lens and replaces it with an intraocular lens (IOL). This surgery is particularly beneficial for people with high prescriptions who may not be eligible for laser refractive surgery.
The surgeon selects the type of IOL depending on the vision correction you need, which may include:
- Toric IOL for astigmatism
- Multifocal or accommodating IOL for presbyopia (presbyopic lens exchange or PRELEX)
Phakic intraocular lens implants (Phakic IOL)
Phakic IOL is a lens implant that corrects high levels of myopia. Instead of removing the natural lens like RLE procedures, the natural lens stays in place. A phakic IOL can be removed or replaced later on.
Two types of phakic IOLs include:
- Anterior chamber phakic IOL (IOL inserted between the cornea and iris)
- Posterior chamber phakic IOL (IOL inserted in front of the natural lens)
Is Refractive Surgery Safe?
In general, refractive surgeries are considered safe and effective. Of course, all surgeries come with some risk, and the rate of complications varies depending on the type of procedure.
Some potential risks of refractive surgery include:
- Glare or halos (that do not improve after a typical recovery period)
- Blurry vision (that does not improve after a typical recovery period)
- Elevated eye pressure
- Retinal detachment
A review of several LASIK studies published between 2008 and 2015 found that over 98% of patients were satisfied with their LASIK outcome. The rate of complication ranges from 0.7% to 6.6%, which is considered low.
Lens implant surgeries are more invasive than laser refractive surgeries and generally carry a higher risk of complications. For example, the risk of retinal detachment is higher with an RLE procedure (about 1.5% to 8.1% in those with high myopia) versus laser refractive surgery (about 0.05% to 0.19% among LASIK patients).
How Long Does Refractive Surgery Last?
The effects of refractive surgery are permanent. However, the surgeon can replace phakic IOLs if your vision changes or remove them if you need cataract surgery. With RLEs, the implant is permanent.
Because laser refractive surgeries remove tissue from your cornea, the effects cannot be reversed. However, your vision can change after surgery for other reasons, for example, if the focusing power of your natural lens changes.
Tips: Choosing the Right Procedure
With many options for refractive surgery, choosing the right procedure can be overwhelming. Here are some areas to consider:
- Do you have dry eye? During LASIK, the creation of a corneal flap can lead to increased dry eye. Although these symptoms typically improve over time, people with chronic dry eye may want to avoid LASIK.
- Do you participate in activities where eye trauma is likely? This may include people who engage in high-impact sports and military or law enforcement personnel. Because of the corneal flap created during LASIK, the corneal structure is weaker versus procedures that do not involve a flap. PRK is a better option in this case (or SMILE if you have myopia).
- Do you have thin corneas? The surgeon can perform a quick test to determine the thickness of your corneas. If they are thin, your surgeon may perform PRK instead of LASIK. Alternatively, the surgeon may recommend an RLE or phakic IOL to avoid the risk of abnormal corneal thinning (ectasia).
- How strong is your prescription? If your prescription is very high, you may not be eligible for LASIK or other laser refractive surgeries. The higher your prescription, the more corneal tissue the surgeon must remove, which increases your risk for corneal ectasia. An RLE or phakic IOL may be a more suitable option.
- Can you take time off work or school? LASIK and SMILE have rapid recovery times and allow you to resume most normal activities within a day. The other procedures may require a little more downtime.
- Are you over 40? Most people start to experience presbyopia (loss of ability to see up close) shortly after age 40. Additionally, age-related cataracts develop around age 60. In these cases, your surgeon may recommend an RLE. An RLE can correct presbyopia with multifocal or accommodating IOLs. Since the RLE removes your natural lens, you cannot develop a cataract afterward.
Ultimately, you should consult your ophthalmologist to determine which procedure is best for you.