Laser Eye Surgery: LASIK, LASEK & Refractive Procedures Explained

What Is Laser Eye Surgery and How Does It Work?

Laser eye surgery, also called refractive surgery, uses precise laser technology to reshape the cornea and correct vision problems including nearsightedness, farsightedness, and astigmatism. The procedure changes how light focuses on the retina, reducing or eliminating the need for glasses or contact lenses.

The human eye works like a camera, with the cornea and lens focusing light onto the retina at the back of the eye. When this focusing system has imperfections, known as refractive errors, images appear blurry. Approximately 2.7 billion people worldwide have refractive errors that could benefit from correction, making these among the most common vision problems globally.

Laser eye surgery addresses these focusing problems by precisely removing microscopic amounts of corneal tissue, changing its curvature to improve how light enters the eye. Modern excimer lasers used in these procedures can remove tissue with accuracy measured in micrometers (thousandths of a millimeter), enabling highly predictable outcomes. The laser itself does not generate heat that could damage surrounding tissue, instead using ultraviolet light to break molecular bonds in the cornea.

The development of laser refractive surgery represents one of the most significant advances in ophthalmology over the past three decades. Since the first LASIK procedure was performed in 1991, techniques have continuously improved, with modern procedures offering faster recovery, better visual outcomes, and lower complication rates than ever before. Today, millions of procedures are performed annually worldwide, with extensive long-term data supporting their safety and effectiveness.

Types of Refractive Errors Treated

Myopia (nearsightedness) occurs when the eye is too long or the cornea too curved, causing distant objects to appear blurry while near objects remain clear. This is the most common refractive error treated with laser surgery, and modern techniques can correct myopia up to approximately -10 to -12 diopters, depending on corneal thickness.

Hyperopia (farsightedness) results from an eye that is too short or a cornea that is too flat, making near objects blurry while distant vision may be relatively clearer. Laser surgery can typically correct hyperopia up to +4 to +6 diopters, though the range depends on the specific procedure and individual eye characteristics.

Astigmatism occurs when the cornea has an irregular shape, more like a football than a basketball, causing blurry vision at all distances. Most astigmatism up to 6 diopters can be corrected during laser procedures, often simultaneously with myopia or hyperopia treatment.

What Are the Different Types of Laser Eye Surgery?

The main types of laser eye surgery are LASIK (flap-based), LASEK/PRK (surface ablation), and SMILE (small incision lenticule extraction). Each technique reshapes the cornea differently, with selection based on corneal thickness, refractive error severity, lifestyle factors, and surgeon expertise.

Understanding the differences between laser eye surgery techniques helps patients and their ophthalmologists choose the most appropriate procedure. While all methods achieve similar visual outcomes, they differ in recovery time, comfort during healing, and suitability for different eye conditions. The choice often depends on factors including corneal thickness, pupil size, occupation, and lifestyle activities.

LASEK and PRK (Surface Ablation)

LASEK (Laser-Assisted Sub-Epithelial Keratomileusis) and PRK (Photorefractive Keratectomy) are surface ablation procedures that treat the cornea without creating a deep flap. In LASEK, the surgeon uses a dilute alcohol solution to loosen and move aside the thin outer layer of the cornea (epithelium) before applying the excimer laser to reshape the underlying tissue. In PRK, the epithelium is completely removed rather than preserved.

These surface procedures are particularly suitable for patients with thinner corneas who may not have sufficient tissue for safe LASIK flap creation. They are also preferred for individuals in contact sports or occupations with higher risk of eye trauma, as there is no flap that could potentially be dislodged. Military personnel and professional athletes often choose surface ablation for this reason.

The primary trade-off with surface procedures is a longer and initially more uncomfortable recovery period. Because the epithelium must regenerate, patients typically experience 3-5 days of moderate discomfort, light sensitivity, and blurry vision before improvement begins. Full visual stabilization usually takes 1-3 months, compared to days for LASIK. However, long-term visual outcomes are equivalent to LASIK, and some studies suggest slightly lower risk of dry eye symptoms.

During a LASEK procedure, after applying anesthetic drops, the surgeon places a special device to keep the eye open and centered. An alcohol solution softens the epithelium for approximately 30 seconds, allowing it to be gently moved aside as a sheet. The excimer laser then reshapes the corneal stroma in a treatment typically lasting 30-60 seconds, depending on the correction needed. The epithelium is repositioned and a bandage contact lens placed for protection during healing.

LASIK (Laser-Assisted In Situ Keratomileusis)

LASIK remains the most commonly performed laser vision correction procedure worldwide, with millions of successful surgeries performed annually. The procedure involves creating a thin flap in the cornea, lifting it to expose the underlying tissue, and using an excimer laser to reshape the corneal stroma before repositioning the flap.

The corneal flap can be created using either a mechanical microkeratome (a precision blade device) or a femtosecond laser. Femtosecond laser-assisted LASIK, sometimes called "bladeless LASIK" or "all-laser LASIK," offers greater precision in flap creation and has become increasingly standard at modern refractive surgery centers. The femtosecond laser creates the flap using rapid pulses of light that separate tissue at a precise depth without cutting.

LASIK's primary advantage is rapid visual recovery. Most patients notice dramatically improved vision within hours of the procedure, and many achieve driving-quality vision by the next day. Discomfort is typically minimal, described as a mild gritty sensation that resolves within several hours. This quick recovery makes LASIK particularly attractive for those who cannot take extended time away from work or activities.

The procedure itself takes approximately 10 minutes per eye. After numbing drops are applied, a suction ring stabilizes the eye while the flap is created (about 20-30 seconds). The surgeon then lifts the flap, exposing the corneal bed. Patients focus on a target light while the excimer laser delivers the calculated treatment, which typically takes 30-60 seconds of active laser time. The flap is then repositioned, where it adheres naturally without stitches.

LASIK candidates should have stable prescriptions (unchanged for at least one to two years), adequate corneal thickness, no significant eye diseases, and realistic expectations. Conditions that may disqualify candidates include keratoconus, severe dry eye syndrome, uncontrolled diabetes, autoimmune diseases affecting healing, and pregnancy or nursing.

SMILE (Small Incision Lenticule Extraction)

SMILE represents the newest major advancement in laser vision correction, first approved in 2011 and gaining widespread adoption since. Unlike LASIK and LASEK, SMILE does not involve surface ablation with an excimer laser. Instead, a femtosecond laser creates a thin disc of tissue (lenticule) within the cornea, which the surgeon then removes through a small incision.

The SMILE procedure requires only a small incision of 2-4 millimeters, compared to the approximately 20 millimeter circumference of a LASIK flap. This minimally invasive approach preserves more of the corneal nerves responsible for tear production and surface sensation, potentially reducing dry eye symptoms after surgery. Studies have shown faster nerve regeneration and less dry eye with SMILE compared to LASIK.

SMILE was initially approved only for myopia correction but has since been expanded to include astigmatism treatment. The range typically extends to -10 diopters of myopia and up to 5 diopters of astigmatism. Hyperopia treatment with SMILE is currently under investigation but not yet widely available.

Recovery from SMILE falls between LASIK and surface ablation. While not quite as rapid as LASIK, most patients achieve functional vision within 1-2 days and experience minimal discomfort. The absence of a flap eliminates flap-related complications and may make SMILE suitable for patients with active lifestyles or occupations with eye trauma risk.

What Are Implantable Lenses (ICL) for Vision Correction?

ICL (Implantable Collamer Lens) is a surgical procedure where a thin artificial lens is permanently placed inside the eye, in front of the natural lens, to correct severe nearsightedness or farsightedness that cannot be safely treated with laser surgery.

Implantable contact lenses offer an excellent alternative for patients who are not candidates for laser vision correction due to thin corneas, high refractive errors, or dry eye syndrome. Unlike laser procedures that permanently remove corneal tissue, ICL surgery is potentially reversible since the lens can be removed or exchanged if needed.

The ICL is made of Collamer, a biocompatible material that includes collagen, making it highly compatible with the eye's natural chemistry. The lens is positioned behind the iris and in front of the crystalline lens, in a space called the posterior chamber. Because the cornea remains untouched, patients typically do not experience the dry eye symptoms sometimes associated with laser procedures.

ICL surgery is particularly well-suited for younger patients (typically under 45) with high myopia (-6 to -20 diopters) or significant hyperopia who want excellent quality of vision. The procedure can also correct astigmatism when combined with a toric ICL design. Visual recovery is typically rapid, with most patients seeing clearly within 24 hours.

The surgical procedure takes approximately 15-20 minutes per eye. After dilating the pupil and applying anesthetic drops, the surgeon makes a small incision at the edge of the cornea. The folded ICL is inserted through this incision and unfolds once inside the eye. The surgeon positions the lens behind the iris, and the incision typically self-seals without stitches.

Important considerations for ICL include the need for careful measurements to ensure proper lens sizing, monitoring of intraocular pressure, and long-term follow-up to assess lens position. Though rare, potential complications include cataract formation, increased eye pressure, and endothelial cell loss. However, modern ICL designs with central flow-through ports have significantly reduced these risks.

What Is Refractive Lens Exchange (RLE)?

Refractive Lens Exchange (RLE), also called clear lens extraction, replaces the eye's natural lens with an artificial intraocular lens (IOL) to correct vision. This procedure is essentially cataract surgery performed for refractive purposes, primarily recommended for patients over 45-50 years old.

RLE addresses vision problems by replacing the eye's natural crystalline lens rather than reshaping the cornea. The procedure is identical to cataract surgery in technique, but performed on eyes with clear lenses for the purpose of correcting refractive errors. This approach is particularly valuable for patients who have or will soon develop presbyopia, the age-related loss of near focusing ability.

The primary advantage of RLE is that it can simultaneously correct distance vision, astigmatism, and presbyopia using advanced multifocal or extended depth of focus lenses. Additionally, since the natural lens is removed, the patient will never develop cataracts. This makes RLE an attractive option for patients in their late 40s or older who would otherwise face cataract surgery within the coming decades.

Modern intraocular lenses used in RLE offer several options. Monofocal lenses provide excellent vision at one distance (usually far), with reading glasses needed for near tasks. Multifocal lenses use different zones to provide clear vision at multiple distances, potentially eliminating glasses entirely. Trifocal lenses provide sharp vision at near, intermediate (computer distance), and far distances. Extended depth of focus (EDOF) lenses provide a continuous range of vision with fewer visual disturbances than traditional multifocals.

The RLE procedure typically takes 15-20 minutes per eye. After numbing the eye, the surgeon makes a small incision and uses ultrasound energy (phacoemulsification) to break up and remove the natural lens. The artificial IOL, which is foldable, is inserted through the same small incision and unfolds into position within the lens capsule. Most patients have both eyes treated on the same day or within a week of each other.

Recovery from RLE is generally quick, with many patients noticing improved vision within days. However, adaptation to multifocal lenses can take several weeks as the brain learns to interpret the new visual information. Some patients may notice halos around lights at night, particularly with multifocal designs, though these typically diminish over time.

Who Is a Good Candidate for Laser Eye Surgery?

Good candidates for laser eye surgery are at least 20 years old with stable vision for 2 years, have mild to moderate refractive errors, sufficient corneal thickness, healthy eyes without keratoconus or severe dry eye, and are not pregnant or nursing. A comprehensive eye examination determines individual eligibility.

Determining candidacy for refractive surgery involves a thorough evaluation of multiple factors. Not everyone who desires freedom from glasses is a suitable candidate, and a careful assessment helps ensure safe procedures with satisfactory outcomes. The pre-operative evaluation typically includes measurements of corneal thickness and curvature, pupil size, refractive error, and overall eye health.

Age requirements exist because the eye continues developing into the early twenties, and refractive errors can shift during this time. Most surgeons require patients to be at least 20 years old with a stable prescription (unchanged for 12-24 months) before considering surgery. There is no strict upper age limit, though patients over 45-50 often benefit more from lens-based procedures like ICL or RLE due to presbyopia.

Refractive error ranges suitable for laser correction vary by procedure. LASIK and LASEK typically treat myopia up to -10 to -12 diopters, hyperopia up to +4 to +6 diopters, and astigmatism up to 6 diopters. SMILE currently treats myopia up to -10 diopters with astigmatism up to 5 diopters. Higher prescriptions may be better suited for ICL implantation.

Corneal requirements are crucial for laser procedures since tissue is permanently removed. Sufficient thickness must remain after the procedure to maintain corneal stability and prevent ectasia (weakening and bulging). Corneal topography mapping identifies irregularities or early keratoconus that would contraindicate laser treatment.

How Should You Prepare for Laser Eye Surgery?

Preparation for laser eye surgery includes stopping contact lens wear (soft lenses 1-2 weeks before, hard lenses 3-4 weeks before), attending a comprehensive pre-operative evaluation, arranging transportation home, and following specific instructions about medications and eye drops.

Proper preparation significantly contributes to successful outcomes and smooth recovery. Your ophthalmologist will provide specific instructions based on the procedure planned and your individual circumstances, but several general guidelines apply to most refractive surgery patients.

Contact lens cessation is essential because lenses temporarily alter corneal shape, affecting the accuracy of pre-operative measurements. Soft contact lenses should typically be discontinued 1-2 weeks before the evaluation and surgery, while rigid gas permeable (hard) lenses require 3-4 weeks or longer. Your surgeon may request additional time if measurements remain unstable.

The pre-operative evaluation involves comprehensive testing including refraction, corneal mapping (topography and tomography), measurement of corneal thickness (pachymetry), pupil size assessment, tear film evaluation, and examination of the retina and optic nerve. These tests determine your candidacy and guide treatment planning.

On the day of surgery, you should avoid wearing eye makeup, lotions, or perfumes that could interfere with the procedure or increase infection risk. Wear comfortable clothing and arrange for someone to drive you home, as your vision will be blurry immediately after surgery. Most procedures are performed on an outpatient basis and take less than 30 minutes total for both eyes.

What Are the Risks and Side Effects of Laser Eye Surgery?

Common temporary side effects include dry eyes, glare, halos around lights, and light sensitivity lasting days to weeks. Serious complications are rare, occurring in less than 1% of cases, and may include infection, corneal ectasia, significant under or over-correction, and rarely, vision loss requiring additional treatment.

Understanding potential risks allows patients to make informed decisions and recognize when to seek medical attention during recovery. While laser eye surgery has an excellent safety profile developed over decades of research and millions of procedures, no surgery is without risk. Thoroughly discussing these possibilities with your surgeon helps establish realistic expectations.

Common Temporary Side Effects

Dry eye symptoms are the most common complaint after laser eye surgery, affecting up to 50% of patients in the first few weeks. The corneal nerves responsible for triggering tear production are disrupted during surgery and take time to regenerate. Most patients experience significant improvement within 3-6 months, though some may have persistent dryness requiring ongoing treatment. SMILE appears to cause less dry eye than LASIK due to smaller nerve disruption.

Visual disturbances such as glare, halos around lights, starbursts, and reduced contrast sensitivity are common in the immediate post-operative period, particularly in low-light conditions. These symptoms usually diminish significantly within weeks to months as the cornea heals and stabilizes. Patients with large pupils may be at higher risk for persistent symptoms.

Fluctuating vision during healing is normal, especially in the first weeks after surface ablation procedures. The cornea continues to remodel for several months, and vision typically stabilizes by 3 months post-operatively. Some patients may notice temporary worsening of vision before it improves to its final level.

Rare but Serious Complications

Infection (keratitis) is rare, occurring in approximately 1 in 2,000 to 1 in 5,000 cases. When it occurs, prompt treatment with intensive antibiotic therapy is essential to prevent scarring and vision loss. Patients are prescribed prophylactic antibiotic drops to minimize this risk.

Corneal ectasia is a progressive weakening and bulging of the cornea that can occur months to years after surgery. Modern screening techniques, including corneal tomography and biomechanical assessment, have significantly reduced this risk by identifying susceptible individuals before surgery. The incidence is approximately 1 in 2,500 cases.

Under-correction, over-correction, or regression may occur in approximately 5-10% of cases, potentially requiring enhancement surgery or continued use of glasses for certain activities. Enhancement procedures are typically performed 3-6 months after the initial surgery once the cornea has stabilized.

What Is the Recovery Process After Laser Eye Surgery?

Recovery varies by procedure: LASIK patients typically see clearly within hours and return to normal activities in 1-2 days. LASEK/PRK requires 1-2 weeks for initial healing with full stabilization in 1-3 months. All procedures require antibiotic and anti-inflammatory drops, avoiding eye rubbing, and multiple follow-up appointments.

The recovery experience differs substantially between laser procedures, primarily based on whether the corneal surface is disrupted. Understanding what to expect helps patients prepare appropriately and recognize normal healing versus concerning symptoms.

LASIK Recovery Timeline

LASIK offers the fastest recovery of all refractive procedures. Many patients notice dramatically improved vision within hours of surgery, though some initial haziness is normal. Most patients can return to work and normal activities within 1-2 days, though strenuous exercise, swimming, and eye makeup should be avoided for 1-2 weeks.

Post-operative care for LASIK includes prescribed antibiotic drops (typically for 1 week) and anti-inflammatory steroid drops (typically for 1-2 weeks). Artificial tears are recommended frequently during the first few months to combat dry eye symptoms. Protective shields may be worn at night for the first week to prevent inadvertent eye rubbing during sleep.

LASEK/PRK Recovery Timeline

Surface ablation procedures require longer recovery because the epithelium must regenerate. The first 3-5 days typically involve moderate discomfort, light sensitivity, and blurry vision. A bandage contact lens placed during surgery remains for approximately 4-7 days until the epithelium heals. Pain medication may be prescribed for the first few days.

Vision improvement begins once the bandage lens is removed and continues gradually over the following weeks. Most patients achieve functional vision within 1-2 weeks but may not reach their best vision for 1-3 months. Steroid eye drops are used for a longer period (1-3 months) compared to LASIK to prevent haze formation.

General Recovery Guidelines

Regardless of procedure, certain precautions apply to all laser eye surgery patients during recovery:

• Avoid rubbing your eyes for at least 2-4 weeks (longer for LASIK to protect the flap)
• Use prescribed eye drops exactly as directed to prevent infection and promote healing
• Wear sunglasses outdoors to protect against UV exposure and reduce light sensitivity
• Avoid swimming pools, hot tubs, and natural bodies of water for 2-4 weeks to prevent infection
• Do not wear eye makeup for at least 1-2 weeks
• Attend all follow-up appointments (typically at 1 day, 1 week, 1 month, and 3 months)

How Long Do Laser Eye Surgery Results Last?

The corneal reshaping from laser eye surgery is permanent, but eyes can still change over time. Approximately 10-20% of patients may experience some regression over 10 years. Presbyopia (age-related near vision loss) will still develop after age 40-45, and some patients may eventually need glasses for reading or other activities.

Long-term studies following LASIK patients for 10-20 years demonstrate that the vast majority maintain excellent vision without glasses for their primary activities. The structural changes made to the cornea do not reverse or heal back to the original shape. However, several factors can affect long-term visual outcomes.

Refractive regression refers to a gradual return of some refractive error over time. This occurs in approximately 10-20% of patients over 10 years, more commonly in those who had higher initial prescriptions. Regression is usually mild and can often be corrected with an enhancement procedure if desired.

Presbyopia is an inevitable age-related change where the lens loses its flexibility, reducing the ability to focus on near objects. This occurs in everyone around age 40-45, regardless of whether they have had laser surgery. Patients who had refractive surgery may need reading glasses as they enter their mid-40s, even if their distance vision remains excellent.

Cataracts can develop later in life as a natural part of aging and will affect vision regardless of previous refractive surgery. The presence of prior laser surgery does not increase cataract risk but does require modified IOL calculations if cataract surgery becomes necessary.

When Should You Seek Medical Care After Eye Surgery?

Contact your surgeon immediately if you experience sudden vision loss, severe pain not relieved by medication, increasing redness or discharge, or any symptom that concerns you. Most complications are treatable when caught early, making prompt communication with your medical team essential.

While serious complications are rare, knowing warning signs ensures prompt treatment when needed. Your surgical center will provide emergency contact information and specific guidance about when to call. Do not hesitate to reach out if something seems wrong, as early intervention can prevent serious problems.

In a medical emergency involving your eyes or if you cannot reach your surgeon, seek care at the nearest emergency room or urgent eye care facility. Inform them of your recent surgery and bring any information about the procedure if available.