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Small incision lenticule extraction (SMILE) is a procedure designed to treat mild myopia with or without associated mild astigmatism. Myopia is the most common refractive error, caused by a misshapen cornea and lens.
This laser-guided eye procedure was approved by the U.S. Food and Drug Administration (FDA) in 2016. It has been available to other countries for at least 10 years before that, so there are many medical studies on SMILE’s effectiveness.
Using a laser, your ophthalmologist will create a lenticule in your lens and then remove it, so the cornea flattens. Light is then refracted more clearly onto your retina.
Generally, adults with healthy eyes and a specific range of myopia and astigmatism are great candidates for SMILE. Changing myopia, unhealthy eyes, or other eye or health conditions mean you may not be a good candidate.
The operation itself is simple, taking only 10 to 15 minutes total per eye. You will have much of your vision back after one to two days of recovery. The operation costs between $2,000 and $3,000 on average, just like LASIK. Side effects and risks are also similar to LASIK, with less risk of corneal flap problems and lower chances of scarring or dry eye.
Overall, SMILE can help more people achieve better vision now that it is increasingly available in the United States.
When Is SMILE Used?
Myopia is one of the most common refractive errors, leading to blurry distance vision. Often, nearsightedness is treated with glasses or contact lenses. Increasingly, people who are tired of these options pursue laser-assisted in situ keratomileusis (LASIK). Myopia is a condition caused by problems with the shape of the cornea and lens. These two small parts of the eye refract light through your pupil and onto your retina, which sends these signals through the optic nerve to the brain.
People with clear vision have corneas and lenses shaped to refract light directly onto the retina, so a clear image is processed in the brain. People who have a problem with the cornea and lens may not get enough light refracted through the eye, or the light may hit in a way that the brain processes it as a blurry or doubled image. Nearsightedness means your brain can process images of close-up objects correctly, but far objects will appear blurry.
A recent survey found that about 40 percent of the United States population has some degree of myopia. According to this study, more people around the world are being diagnosed with this vision condition. The researchers estimate that by 2050, about 5 billion people, or half the global population, will have myopia.
While these rates may appear alarming, advancements in eye surgery, like SMILE, can provide better long-term treatment solutions to vision problems, especially mild myopia.
How Does SMILE Work?
Like other types of laser surgery such as LASIK, the SMILE procedure uses a laser, guided by your ophthalmologist, to change the shape of your cornea. By adjusting the shape of this part of your eye, light will be refracted back onto the retina more clearly, so your brain will process a clearer image of distant and near objects.
The U.S. Food and Drug Administration (FDA) approved SMILE in September 2016 to treat mild myopia, with or without astigmatism. SMILE has been available in several other countries for more than 10 years prior to its approval in the U.S. About 1.5 million SMILE procedures have been approved worldwide as of 2017. This operation is well understood, with more than 400 clinical studies determining its safety and effectiveness for specific people.
The goal of SMILE treatment is to improve your vision. Like other laser-guided vision-correcting procedures, you are not guaranteed to have “perfect” vision at the end of the procedure. However, your vision will be improved. In rare cases, you may still need glasses or contact lenses for some activities. On average, about 99 percent of people who undergo SMILE have 20/40 vision at their six-month follow-up appointment, and 88 percent have 20/20 vision at that point.
The SMILE procedure is designed to be even simpler than LASIK, which is already a short outpatient operation with a brief recovery time. While LASIK involves cutting part of the corneal tissue back and reshaping the internal structure, SMILE uses a guided laser to make small cuts or incisions on the cornea itself, rather than into the lens.
The laser cuts a disc-shaped piece of the top layer of corneal tissue called the lenticule, which is thicker at the center and thinner at the edges of your eye. When the lenticule is removed, the overall tissue flattens your cornea, which reduces myopia and can reduce astigmatism, in some cases.
The first SMILE procedures were performed in 2008 and 2009, on 91 eyes. Of this group, 56 people had their eyes re-examined in a five-year follow-up to measure the success of the procedure. There was little change in visual acuity compared to the group’s six-month follow-up, although some had a minor regression of myopia, which is to be expected after many laser refractive procedures.
Who Benefits From SMILE? Who Is Not a Good Candidate?
- Are at least 22 years old.
- Do not have consistently changing vision for at least a year.
- Have no other vision problems like cataracts or glaucoma.
- Have healthy corneas overall.
- Have a nearsightedness prescription between -1.00 and -10.00 diopters in power, with no more than -8.00 diopters being ideal.
- Have astigmatism of -0.75 to -3.00 diopters.
- Have a total prescription, combining astigmatism and nearsightedness, that does not exceed -10.00 diopters.
A clinical study of 348 SMILE recipients found that, after the treatment, all but five had visual acuity that improved to 20/40 or better, so they did not need glasses or contact lenses for most activities. Of those, 84 percent had 20/20 vision after full healing from the procedure.
Although many people can benefit from SMILE, just like millions of people have benefitted from LASIK, there are still some individuals who are not good candidates for this laser procedure. You may not be a good candidate for SMILE if:
- You have an unstable refractive error that changes more than -0.50 diopters in a year.
- You have hyperopia or presbyopia, two types of farsightedness.
- You have a condition that affects how quickly you heal.
- You are pregnant or nursing.
- You have uncontrolled diabetes.
- You have excessive scarring or keloid formation.
- You have keratoconus, or an unusual bulging shape to your cornea.
- You have a corneal disease or corneal abrasions.
- You have advanced glaucoma.
- You have a cataract impacting your vision.
- You have thin corneas.
- You have a history of eye disease or certain infections.
- You have had laser surgery on your eyes in the past.
Understanding the SMILE Procedure
SMILE is a simple, fast, and low-impact laser surgery. While you will not spend a lot of time in the operating room, you will need to work with your ophthalmologist to plan the operation and understand what happens after it is complete.
- Preparation: The first step in preparing for SMILE is to receive a diagnosis from an ophthalmologist. This allows you to discuss your concerns and expectations with your eye doctor, so you understand what to expect in terms of healing times, risks, and other factors.
Preparation for SMILE may also include:
- A comprehensive eye exam so your ophthalmologist fully understands your eye health.
- Confirmation that you do not have any other vision problems, like high fluid pressure indicating potential glaucoma.
- Mapping the surface of your cornea so your ophthalmologist can program the laser to make the appropriate lenticular incisions.
- Measurements of your pupil size.
- The procedure: SMILE takes between 10 and 15 minutes per eye. The laser will be programmed with the map of your eye, and your surgeon will numb your eye with drops. Your eyelids will be held back with a special holder, so you do not blink, but the guided laser also has protective measures in place to manage any twitching you do during surgery.
Once you are in place, a suction ring will be placed on your cornea, which will also prevent your eye from moving. The laser will fire, sculpting the lenticule in your cornea. Your surgeon will then remove this shape from your lens. This part of the operation will take about 30 seconds.
- Aftercare: Although healing does not take long after SMILE, you will still need someone to drive you home. You should take the day off from anything that requires using your vision, like watching television, working, or reading.
Your surgeon will prescribe eye drops to prevent infection. Use these as directed.
You should be able to see the next day, although your vision may be a little blurry for up to a few weeks after the operation as your cornea reshapes and heals. You should avoid any activities that might get particles in your eyes, including swimming, for a few days, until your ophthalmologist clears you. You should be able to return to low-impact normal daily routines one or two days after the procedure.
How Much Does SMILE Cost?
As SMILE becomes more popular and it becomes easier for ophthalmologists to get the right training and equipment, the cost of the operation is going down. According to Market Scope U.S. Refractive Surveys (2019), the cost of SMILE has decreased from about $4,290 in 2016 to $2,361 in 2019. This can change based on where you live, what your individual ophthalmologist charges, and where their practice is located. However, you can expect to pay between $2,000 and $3,000 per eye for SMILE. This is similar to the cost of LASIK and related laser-guided eye surgeries.
For years, vision insurance companies have considered procedures like LASIK to be cosmetic surgery, and they did not offer coverage. However, this is changing. LASIK, SMILE, PRK, and similar laser operations are improving, more people are seeking them out, and the lasting eye treatments save vision insurance companies money on prescription coverage. You may not have coverage for a newer operation like SMILE, so check with your insurance company first.
If you have a flexible spending arrangement (FSA) or a health savings account (HSA), you can use the money in this health insurance-adjacent plan to pay for SMILE. Many surgical practices also offer discounts or flexible payment plans. Sometimes, patients take out small loans or use low-interest credit cards to cover the costs of these operations.
Side Effects, Recovery Time & Risks of SMILE
Recovery does not take long, and common side effects from SMILE are similar to those of LASIK or other laser-guided eye treatments. While usually temporary, potential side effects include:
- Halos around lights.
- Dry eye.
- Debris at the site of tissue removal.
- Inflammation in the tissues.
- Need for retreatment with a more intensive procedure like photorefractive keratectomy (PRK).
Like other laser eye procedures, SMILE may overcorrect or undercorrect your vision. Undercorrections can be treated with glasses, contact lenses, or a future laser-guided procedure if your corneas are thick enough. Overcorrection requires a future procedure to adjust your vision.
Unlike other laser procedures, there is no risk of corneal flap displacement and much less risk of scar tissue growth that obscures vision. There is lower risk of dry eye after this procedure. This is because fewer corneal nerves are interrupted so you can retain more sensation in your eyes.
It is extremely rare to suffer complications from SMILE, but it is possible. Side effects typically go away, but in rare cases, you may have halos or dry eye permanently. You may also:
- Have worse vision than before the operation, even with glasses or contact lenses.
- Develop blindness.
Again, these complications are incredibly rare. Most people experience positive results from SMILE.
SMILE Can Improve Vision
Although SMILE is a new procedure in the U.S., it is quickly becoming a viable option to help people who have myopia, with or without astigmatism. In the future, similar procedures may be developed to help astigmatism specifically or both types of farsightedness. However, having a procedure that specifically improves visual acuity for people with nearsightedness means that much of the world’s population can improve their vision.
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