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Laser-assisted in situ keratomileusis (LASIK) can be performed more than once, but doing so more than three times may be harmful to your eyes and may be futile in the end, causing even more severe vision problems.

• The goal of LASIK is to permanently reshape the cornea. This means that once you've had this life-changing procedure, you may not need to wear glasses or contact lenses for the rest of your life.
• However, a general rule of thumb is that if your vision is blurry even three months after LASIK, you may need to have it corrected.
• Many people benefit from long-term vision correction. People whose vision has changed several years after LASIK may require additional treatment.
• According to a study that looked at the long-term viability of LASIK, 35 percent of people who underwent LASIK required LASIK enhancement after 10 years.
• Most of the time, a repeat surgery after 10 years is required due to an underlying condition that affects the person’s vision.
• Studies report that approximately 95 percent of people are very satisfied with the results and report significantly improved eyesight for several years after surgery.
• However, for the remaining five percent of people, vision correction may fall short of expectations, and they may require laser eye surgery more than one time.
• Fortunately, if the corneal tissue (on the front of your eye) is thick enough and your eyes are healthy, you can receive repeat laser eye treatment, and an ophthalmologist can advise you.

Although a “lifetime guarantee” for LASIK sounds appealing, the unfortunate reality is that LASIK is a surgical procedure, and NO surgical procedure can be guaranteed.

What is LASIK?

Laser-assisted in situ keratomileusis (LASIK) can correct a wide range of refractive errors, including nearsightedness, farsightedness, and astigmatism.

• To correct the person’s vision, a computer-controlled excimer laser is used to reshape the cornea.
• Laser reshaping is performed under a protective flap of tissue to promote rapid vision recovery and minimize discomfort.

Three conditions that are corrected by LASIK include:

1. Myopia (nearsightedness): In this condition, you can see nearby objects clearly but not distant objects. Light rays focus in front of the retina and blur distant vision when your eyeball is slightly longer than normal or when the cornea curves too sharply.
2. Hyperopia (farsightedness): In this condition, distant objects are visible but nearby objects are blurry. When you have an eyeball that is shorter than average or a cornea that is too flat, light focuses behind the retina rather than on it, causing blurring of nearby objects.
3. Astigmatism: Astigmatism is when the cornea curves or flattens unevenly, disrupting the focus of near and distant vision.

How LASIK surgery is performed

• An ophthalmologist will take detailed measurements of your eye and evaluate its overall health.
• You might be on mild sedatives just before the procedure. Eye-numbing drops may be administered once you are on the operating table.
• A special type of cutting laser may be used by the ophthalmologist to precisely alter the curvature of your cornea.
• Each laser pulse removes a small amount of corneal tissue, allowing the ophthalmologist to flatten or steepen the curve of your cornea.
• Typically, the ophthalmologist makes a flap in the cornea and then raises it before reshaping the cornea.
• There are variations in which a very thin flap is raised, no flap is used or no flap is raised at all. Each technique has benefits and drawbacks.

Specific types of laser eye procedures may be specialized by individual ophthalmologists.

5 types of LASIK

The 5 types of laser-assisted in situ keratomileusis (LASIK) include:

1. LASIK:
   • LASIK is the most commonly performed eye laser surgery and involves creating a partially thick corneal flap and ablation of the corneal bed with an excimer laser. The flap is then returned to its original position.
   • Discomfort is minimal after surgery, and vision recovery usually takes one to two days.
2. Photorefractive keratectomy (PRK):
   • Instead of forming a flap, PRK scrapes away the epithelium (top surface).
   • This corneal abrasion heals in three to four days, causing moderate pain and blurred vision in the short term.
3. Laser-assisted subepithelial keratectomy:
   • In this surgery, a flap is created by using a microkeratome (special cutting device) and exposing the cornea to ethanol.
   • Because the procedure allows the ophthalmologist to remove less of the cornea, it is an excellent choice for people with thin corneas.
4. Epithelial laser-assisted in situ keratomileusis:
   • An epikeratome (a mechanized blunt blade device) is used by the ophthalmologist to separate the epithelium from the stroma (middle part of the cornea), and a laser is used to reshape the cornea.
5. Small-incision lenticule extraction:
   • This newer type of refractive surgery reshapes the cornea by creating a lenticule (a lens-shaped piece of tissue) beneath the cornea's surface with a laser.
   • The lenticule is then removed through a very small incision after it has been used to reshape the cornea.

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8 side effects and complications of LASIK

Although complications are uncommon, certain side effects are common. However, these usually go away after a few weeks or months, and very few people think of them as a long-term issue.

Here are 8 potential side effects and complications of LASIK surgery:

1. Dry eyes:
   • Tear production is temporarily reduced after laser-assisted in situ keratomileusis. Your eyes may feel unusually dry or gritty for the first six months or so after surgery as they heal.
   • Even after you've healed, you may notice an increase in dry eye symptoms.
   • During this time, your eye doctor may advise you to use eye drops.
   • If you have severely dry eyes, you could have special plugs placed in your tear ducts to prevent tears from draining away from the surface of your eyes.
2. Glare, halos, and double vision:
   • You may have difficulty seeing at night after surgery.
   • Glares, halos around bright lights, or double vision are all possibilities.
   • This usually lasts a few days to weeks, but it needs to be treated if it appears to be a chronic issue.
3. Under corrections:
   • If the laser removes too little tissue from your eye, you will not achieve the clearer vision you desired.
   • Nearsighted people are more likely to require corrections. Within a year, you may require another refractive surgery (called an enhancement) to remove more tissue.
4. Overcorrections:
   • There's a chance that the laser will remove too much tissue from your eye. Over corrections might be more difficult to correct than under corrections.
5. Astigmatism:
   • Uneven tissue removal can result in astigmatism. You may require additional surgery, glasses, or contact lenses.
6. Corneal ectasia:
   • Corneal ectasia is one of the more serious complications that occur due to progressive myopia caused by a steepening of the cornea's curvature.
7. Flap problems:
   • During surgery, folding back or removing the flap from the front of your eye can result in complications such as infection and excessive tears.
   • During the healing process, the epithelium (outermost corneal tissue layer) may grow abnormally beneath the flap.
8. Vision loss or changes:
   • You may lose your vision in rare cases due to surgical complications. Some people may not be able to see as sharply or clearly as they used to.

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Am I a good candidate for LASIK?

The U.S. Food and Drug Administration approves laser-assisted in situ keratomileusis (LASIK) for people older than 18 years.

This is the only hard and fast rule when it comes to an age limit for this procedure, but because adult vision is typically at its healthiest between 19 and 40 years, anyone in this range is an excellent candidate.

• Your eyes begin to change when you are about 40 years, and you may develop farsightedness, which may preclude you from being a candidate for LASIK.
• Your eyes begin to change again when you are about 60 years, and age-related vision problems such as cataracts may appear.
• When determining your candidacy, your doctor will consider any changes or variability in your vision caused by age.
• Ophthalmologists typically evaluate older people on a case-by-case basis because their overall eye health is considered.

When evaluating you for LASIK, your ophthalmologist will assess the state of your eyes, including:

• Overall eye health:
  • If you already have dry eye syndrome, cataracts, glaucoma, or another eye condition, you may not be a good candidate for LASIK.
• Pupil size:
  • You may experience glares or halos after LASIK if your pupils are very large.
• Cornea thickness and smoothness:
  • If your cornea is too thin or the surface has an irregular texture, the surgery's outcome may be jeopardized, and your vision may worsen.
• Pregnancy:
  • Hormonal changes associated with pregnancy, and lactation may aggravate dry eye symptoms, which may affect your LASIK candidacy.

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How is LASIK second surgery different from my first?

Laser-assisted in situ keratomileusis (LASIK) second surgery is very similar to your initial surgery. The enhancement, however, does not necessitate the creation of a new corneal flap.

• Your ophthalmologist will use specially designed forceps to lift the flap that was created during the first surgery.
• As with the first LASIK, they will reshape your cornea with a laser-controlled by a powerful computer.
• Because only minor reshaping is required during a LASIK touch-up, the procedure is painless and takes much less time.
• After the procedure, your doctor will call you back for checkups, just like after the primary surgery, and will prescribe eye drops and the same post-operative aftercare as before for the best results.

Whether you require an enhancement, a yearly checkup with your doctor after LASIK is required to ensure optimal eye health.

After LASIK, the majority of people report a high level of satisfaction. However, long-term results are frequently unavailable or have not been thoroughly researched.

Part of the reason for this is that people are generally satisfied with their surgeries, so they don't see the need for repeat examinations, and no follow-up data are collected. 

Furthermore, LASIK has been refined over time, and techniques and technologies are constantly evolving. As a result, concluding the reported data is difficult.

There are no correct answers when it comes to LASIK. Consider the factors carefully, weigh your preferences and risk tolerance, and ensure you have realistic expectations.