LASIK Eye Surgery

LASIK (laser-assisted in situ keratomileusis) is a refractive surgery that uses a laser to permanently reshape the cornea, reducing or eliminating dependence on glasses and contact lenses. It is the most commonly performed elective vision correction procedure in the world and is used to treat myopia (nearsightedness), hyperopia (farsightedness), and astigmatism.

How LASIK Works

The cornea is the clear, dome-shaped front surface of the eye. It is responsible for roughly two-thirds of the eye's focusing power. In a perfectly shaped eye, the cornea bends (refracts) light so that it focuses precisely on the retina. When the cornea's curvature is too steep, too flat, or irregular, light focuses incorrectly—resulting in blurred vision.

LASIK corrects this by reshaping the corneal tissue so that light is focused accurately onto the retina.

The Two-Laser Approach

Modern LASIK uses two lasers:

1. Femtosecond laser — Creates a thin, hinged flap in the outer cornea (the epithelium and part of the stroma). This laser delivers ultrafast pulses of light that precisely separate the tissue layers without a blade.
2. Excimer laser — Removes microscopic amounts of corneal tissue beneath the flap. The excimer laser emits a cool ultraviolet beam that breaks molecular bonds in the tissue, reshaping the cornea with sub-micron accuracy.

For myopia: The laser flattens the central cornea. For hyperopia: The laser steepens the central cornea by removing tissue from the periphery. For astigmatism: The laser creates a more symmetrical curvature across the cornea.

After reshaping, the flap is gently repositioned. It adheres naturally without stitches and heals over the following weeks and months.

Wavefront-Guided vs Wavefront-Optimized

Two main treatment profiles are available:

• Wavefront-guided (custom LASIK): Uses a detailed map of the eye's unique optical imperfections (higher-order aberrations) to create a personalized treatment. This can improve visual quality beyond what glasses or contacts achieve.
• Wavefront-optimized: Applies a standard correction based on your glasses prescription while preserving the natural shape of the cornea's periphery. This approach reduces the risk of inducing new aberrations.

Your surgeon will recommend the best approach based on your eye anatomy and the results of your preoperative testing.

Am I a Candidate?

Not everyone is a good candidate for LASIK. A thorough evaluation by your ophthalmologist will determine whether the procedure is right for you. General requirements include:

Age

• At least 18 years old (most surgeons prefer 21+)
• Your refraction (glasses prescription) should be stable for at least one year—meaning no significant changes in your prescription

Prescription Range

• Myopia up to approximately -12.00 diopters
• Hyperopia up to approximately +6.00 diopters
• Astigmatism up to approximately 6.00 diopters
• Exact limits depend on corneal thickness and individual anatomy

Corneal Requirements

• Adequate corneal thickness—the cornea must be thick enough to safely create a flap and reshape tissue while leaving a sufficient residual stromal bed (typically at least 250 microns)
• Normal corneal topography—no signs of keratoconus or other corneal irregularities
• No history of corneal disease or significant scarring

Eye Health

• No active eye disease such as glaucoma, cataracts, severe dry eye, or uncontrolled uveitis
• Healthy retina with no untreated retinal tears or detachment risk
• Adequate tear film quality and production

General Health

• Not pregnant or nursing (hormonal changes can temporarily alter refraction)
• No uncontrolled autoimmune conditions (e.g., rheumatoid arthritis, lupus)
• No medications that significantly impair healing (e.g., immunosuppressants)
• Realistic expectations about outcomes

If you are not a candidate for LASIK, alternatives such as PRK, ICL (implantable collamer lens), or refractive lens exchange may be options. Your ophthalmologist will discuss the best approach for your specific situation during your consultation.

Before LASIK

Initial Evaluation

Your preoperative assessment is one of the most important steps. It determines whether LASIK is safe and appropriate for your eyes. Expect the following tests:

Corneal topography:

• Maps the curvature and shape of the cornea
• Screens for keratoconus and irregular astigmatism
• Helps plan the laser treatment pattern

Pachymetry:

• Measures corneal thickness at multiple points
• Ensures enough tissue is available for safe reshaping
• Typically performed with ultrasound or optical methods

Cycloplegic refraction:

• Measures your true refractive error with the focusing muscles relaxed
• Prevents over-correction caused by accommodative spasm
• Drops are placed to temporarily paralyze the focusing muscle

Tear film assessment:

• Evaluates tear quantity and quality
• Identifies pre-existing dry eye that may need treatment before surgery
• May include Schirmer's test, tear break-up time, or meibomian gland evaluation

Pupil measurement:

• Measures pupil size in dim lighting
• Very large pupils may increase risk of halos and glare after surgery

Wavefront analysis:

• Maps higher-order aberrations of the eye
• Used to create a customized (wavefront-guided) treatment plan for some patients

Preparing for Surgery

Stop wearing contact lenses before your evaluation and surgery:

• Soft lenses: at least 3-5 days before (some surgeons require 1-2 weeks)
• Toric soft lenses: at least 1-2 weeks before
• Rigid gas permeable (RGP) lenses: at least 3-4 weeks before

Contact lenses temporarily alter the shape of the cornea. Removing them allows the cornea to return to its natural shape for accurate measurements.

Other preparations:

• Arrange for someone to drive you home after surgery
• Plan to take 1-2 days off from work
• Do not wear eye makeup, lotions, or perfume on the day of surgery
• Eat a light meal before the procedure
• Fill any prescribed post-operative eye drops in advance

The Procedure

LASIK is performed as an outpatient procedure. You will be awake throughout. Here is what to expect, step by step:

Step 1: Numbing the Eye

Anesthetic eye drops are placed to completely numb the surface of the eye. You will feel no pain during the procedure. A mild oral sedative may also be offered to help you relax.

Step 2: Positioning and Eye Stabilization

You lie back under the laser. A device called a lid speculum gently holds your eyelids open so you don't need to worry about blinking. A suction ring is applied to the eye to keep it steady during flap creation.

Step 3: Flap Creation (Femtosecond Laser)

The femtosecond laser creates a thin corneal flap, typically 90-120 microns thick. This takes about 20-30 seconds. You may feel pressure but no pain. Your vision dims briefly during this step—this is completely normal.

Step 4: Corneal Reshaping (Excimer Laser)

The surgeon lifts the flap and you are asked to look at a fixation light. The excimer laser then reshapes the underlying corneal tissue according to your personalized treatment plan. An eye-tracking system follows your eye movements in real time to ensure precision. The laser typically fires for 20-60 seconds, depending on the correction needed.

Step 5: Flap Repositioning

The surgeon carefully repositions the flap over the treated area. The flap adheres naturally within minutes. No stitches are needed. The flap's natural suction holds it in place.

Step 6: Completion

The process is repeated on the second eye (if bilateral same-day LASIK). The entire procedure takes approximately 10-15 minutes per eye, with the actual laser time being less than a minute per eye.

After the procedure, you rest briefly and your surgeon examines the flap position under the microscope to confirm proper alignment before you go home.

What You See and Feel During Surgery

During the procedure, you will be looking up at a blinking fixation light. When the femtosecond laser is applied, your vision may temporarily go dark or grey—this is expected and lasts only seconds. During the excimer laser phase, you may notice a faint clicking sound and a mild odor (from the laser interaction with tissue—completely normal). The entire experience, while unusual, is not painful. The surgeon and team will talk you through each step.

After LASIK

First 24 Hours

• Your vision may be blurry or hazy immediately after—this improves quickly
• Mild burning, tearing, or foreign-body sensation is common and usually resolves within a few hours
• Eyes may be light-sensitive—wear the sunglasses provided
• Use prescribed antibiotic eye drops and anti-inflammatory eye drops as directed
• Use artificial tears frequently to keep eyes lubricated
• Wear the protective eye shields while sleeping (usually for the first week)
• Do not rub your eyes—this is critical to protect the healing flap
• Rest and keep your eyes closed as much as possible

Most patients notice a significant improvement in vision within hours of surgery. Some achieve near-clear vision by the next morning.

First Week

• Attend your 1-day post-operative appointment—your surgeon will check flap position, visual acuity, and eye pressure
• Continue all prescribed drops on schedule
• Use artificial tears liberally (every 1-2 hours while awake, or more often if eyes feel dry)
• Avoid swimming, hot tubs, and dusty or smoky environments
• Do not wear eye makeup
• Light activities (computer work, reading, watching TV) are generally fine, but take breaks if eyes feel tired
• Avoid strenuous exercise and contact sports
• Wear sunglasses outdoors to protect from UV light and wind

First Month

• Vision continues to stabilize and sharpen
• Dry eye symptoms are common during this period—continue artificial tears as needed
• Mild halos or glare around lights at night is normal and typically improves over weeks to months
• Attend your 1-week and 1-month follow-up appointments
• Gradually resume normal activities, including exercise (usually after 1-2 weeks, with your surgeon's approval)
• Avoid rubbing your eyes for at least one month (ideally longer)
• Contact sports and swimming can usually resume after 4 weeks

Long-Term

• Most patients enjoy stable, clear vision for years
• Continue to use artificial tears as needed, especially in dry or air-conditioned environments
• Some patients experience persistent dry eye that may require ongoing treatment
• Night vision symptoms (halos, starbursts) usually resolve within 3-6 months but can occasionally persist
• Annual comprehensive eye exams are still important—LASIK does not prevent age-related conditions like presbyopia, glaucoma, or macular degeneration
• Presbyopia (age-related loss of near focus) will still develop in your 40s and 50s, requiring reading glasses regardless of LASIK
• Attend all scheduled follow-up appointments—typically at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year after surgery
• If you experience a sudden decrease in vision, severe pain, or increasing redness at any point, contact your surgeon immediately

LASIK vs Other Options

Several refractive surgery options exist. The best choice depends on your anatomy, prescription, and lifestyle.

PRK (Photorefractive Keratectomy)

• No flap is created—the surface epithelium is removed instead
• The excimer laser reshapes the cornea directly on the surface
• Better for patients with thinner corneas or those at higher risk of flap complications
• Recovery is slower (3-5 days of discomfort, vision stabilizes over weeks)
• Final visual outcomes are comparable to LASIK
• Lower risk of flap-related complications
• Preferred for patients in certain occupations (military, combat sports)

ICL (Implantable Collamer Lens)

• A thin lens is implanted inside the eye, in front of the natural lens and behind the iris
• No corneal tissue is removed
• Reversible—the lens can be removed if needed
• Excellent for high myopia (beyond LASIK range) or thin corneas
• Requires a slightly more invasive intraocular procedure
• Preserves corneal integrity entirely

Refractive Lens Exchange

• The natural lens is removed and replaced with a premium IOL (similar to cataract surgery)
• Best for patients over 45-50 who have early lens changes or presbyopia
• Can correct a wide range of refractive errors
• Eliminates future cataract development
• Carries intraocular surgery risks (infection, retinal detachment)

Comparison Table

Feature	LASIK	PRK	ICL	Refractive Lens Exchange
Corneal flap	Yes	No	No	No
Tissue removed	Yes	Yes	No	Lens replaced
Recovery time	1-2 days	5-7 days	1-2 days	1-2 days
Best for	Mild-moderate refractive error	Thin corneas, surface concerns	High myopia, thin corneas	Presbyopia, early cataracts
Reversible	No	No	Yes	No
Typical age range	21-55	21-55	21-45	45+

Risks and Complications

LASIK is considered very safe, but like any surgery, it carries risks. Understanding these helps you make an informed decision.

Common (Usually Temporary)

• Dry eye — The most common side effect. Occurs because flap creation temporarily disrupts corneal nerves that signal tear production. Usually improves over 3-6 months. Managed with artificial tears and, if needed, punctal plugs or prescription dry eye treatments.
• Halos and glare — Rings of light or starburst patterns around lights at night. More common in the early weeks after surgery. Usually diminish significantly over 3-6 months.
• Visual fluctuations — Mild blurriness that varies with time of day, screen use, or dryness. Typically resolves as the eye heals.

Uncommon

• Undercorrection or overcorrection — The laser may remove slightly too little or too much tissue, leaving residual refractive error. An enhancement (retreatment) procedure can often correct this after the eye has fully stabilized (usually 3-6 months later).
• Regression — A small shift back toward the original prescription over time, more common with higher corrections. May be addressed with an enhancement.
• Flap complications — Wrinkles (striae), displacement, or epithelial ingrowth under the flap. These are uncommon with modern femtosecond flap creation and can usually be treated.
• Diffuse lamellar keratitis (DLK) — Inflammation under the flap ("sands of the Sahara"). Detected early at follow-up visits and treated with steroid drops.

Rare

• Corneal ectasia — Progressive thinning and bulging of the cornea after surgery, similar to keratoconus. Risk is minimized by thorough preoperative screening (topography, pachymetry, residual stromal bed calculations). May require corneal cross-linking or other treatment.
• Infection — Very rare (estimated less than 1 in 5,000). Prevented with prophylactic antibiotic drops and proper surgical technique.
• Chronic dry eye — Persistent dryness requiring ongoing treatment. Uncommon with proper candidate selection.
• Significant loss of best-corrected visual acuity — Extremely rare with modern technology.

Results

Visual Outcomes

LASIK has one of the highest satisfaction rates of any elective procedure:

• 96%+ of patients achieve 20/20 vision or better
• 99%+ of patients achieve 20/40 or better (legal driving vision without correction)
• Patient satisfaction rates consistently exceed 95% in large studies

Results depend on your starting prescription. Mild to moderate refractive errors tend to have the best outcomes. Very high prescriptions carry a slightly higher chance of needing an enhancement.

Enhancements

• Approximately 1-5% of patients may benefit from an enhancement procedure
• Enhancement is typically performed 3-12 months after the initial surgery, once vision has fully stabilized
• The original flap can usually be re-lifted for the enhancement
• Enhancement success rates are high

Important to Know

• LASIK corrects your current refractive error—it does not prevent future changes
• Presbyopia (the need for reading glasses after age 40-45) will still develop, as it is caused by changes in the natural lens, not the cornea
• Some patients opt for monovision LASIK (one eye corrected for distance, one for near) to reduce presbyopia's impact
• Regular eye exams remain essential to monitor for age-related conditions
• LASIK does not increase or decrease the risk of other eye conditions—it simply corrects the refractive error present at the time of surgery
• Patients who had LASIK should inform future eye care providers, as corneal measurements used for cataract surgery IOL calculations are affected by prior LASIK and require special formulas

Frequently Asked Questions

Does LASIK hurt?

No. Numbing eye drops ensure you feel no pain during the procedure. You may feel some pressure during the flap creation step, and a mild burning or scratchy sensation is common for a few hours afterward. Most patients describe the experience as uncomfortable but not painful. Over-the-counter pain relievers and artificial tears are usually all that's needed after surgery.

How long does LASIK last?

The corneal reshaping performed by LASIK is permanent. Your distance vision correction should remain stable for many years. However, LASIK cannot prevent age-related changes. Presbyopia (difficulty with near vision) develops naturally in your 40s, and some patients experience a small degree of regression over decades, particularly those who had high prescriptions. A small percentage of patients may benefit from a touch-up (enhancement) later in life.

Can LASIK be done twice?

Yes, in many cases. If vision changes occur over time or the initial correction was not perfect, an enhancement can often be performed—provided there is adequate remaining corneal thickness. Your surgeon will re-evaluate your corneal topography and pachymetry before recommending a second procedure. If there is insufficient tissue for a safe retreatment, alternatives like PRK or contact lenses may be recommended instead.

When can I drive after LASIK?

Most patients can drive within 1-2 days after surgery, once their vision meets the legal standard (20/40 or better) and they feel comfortable. Your surgeon will assess your visual acuity at the 1-day post-operative visit and advise you. Night driving may take longer to feel comfortable due to temporary halos or glare. Avoid driving immediately after the procedure—you will need someone to drive you home.

What about reading glasses later in life?

LASIK corrects your current distance vision but does not prevent presbyopia, the natural age-related loss of near focusing ability. Virtually everyone over age 45 needs help with near vision, whether or not they have had LASIK. Options include reading glasses, multifocal contact lenses, or monovision LASIK (where one eye is intentionally set for near focus). Discuss your long-term vision goals with your surgeon before the procedure.

References