What is surface ablation surgery?

Common surface ablation techniques include PRK, TransPRK, LASEK and Epi-LASIK. They differ in how the epithelium, the thin outer layer of the cornea, is removed or loosened before an excimer laser reshapes the tissue beneath.

The aim is to reduce dependence on glasses or contact lenses for suitable patients. Surface ablation is often considered when a flap-free approach fits a patient's corneal measurements, ocular surface, or lifestyle better than LASIK.

Surface ablation reshapes the cornea, the clear front window of the eye, to correct short-sightedness, astigmatism and, in selected cases, long-sightedness. The thin surface layer is removed or loosened, and an excimer laser reshapes the corneal tissue beneath. A soft bandage contact lens protects the eye while the surface heals.

Advanced surface ablation, or ASA, is a term used for surface laser techniques such as PRK, TransPRK, LASEK and Epi-LASIK. It does not identify one standard operation or mean that every technique is offered by every clinic.

LASIK creates a thin flap in the cornea before the laser reshaping step. The flap may be made with a femtosecond laser or a mechanical instrument, depending on the method. Surface ablation does not create a LASIK flap. Read more about the LASIK procedure.

The aim is to reduce dependence on glasses or contact lenses. Results vary, and some patients still need glasses for certain tasks. Surgery does not prevent age-related loss of near focusing, known as presbyopia, so reading glasses may still be needed as you get older.

The four types of surface ablation

The four surface ablation techniques differ in how the corneal epithelium is removed or loosened before the excimer laser reshapes the cornea.

PRK (Photorefractive Keratectomy)

PRK is the original excimer laser refractive procedure.

In conventional PRK, the epithelium is removed mechanically using a special instrument, without alcohol. The excimer laser then reshapes the tissue beneath. A bandage contact lens protects the healing surface. TransPRK is a variation in which laser energy removes the epithelium.^[4]

PRK has been performed since the late 1980s and is an established surface ablation technique.

TransPRK (Transepithelial PRK)

TransPRK uses an excimer laser to remove the epithelium and reshape the cornea. Contemporary systems may combine these stages into one treatment sequence; the workflow depends on the laser platform. Manual scraping or alcohol is not used for the epithelial-removal step.

A bandage contact lens is placed afterwards and removed by the clinic once healing is adequate. It may be needed for several days or around a week, depending on the eye's recovery.^[3]

LASEK (Laser Subepithelial Keratectomy)

LASEK loosens the epithelium with a short application of diluted alcohol, then moves the softened epithelial sheet aside before excimer treatment.

In classic LASEK, the epithelial sheet is moved aside and may be repositioned after laser treatment. In some variations it is removed. This surface layer is much thinner than a LASIK flap and does not include the deeper corneal tissue.

Epi-LASIK (Epithelial Laser In Situ Keratomileusis)

Epi-LASIK uses a mechanical separator called an epikeratome to lift the epithelium as a sheet, without using alcohol.

The excimer laser reshapes the underlying tissue. The separated epithelial sheet may be retained or removed, depending on the technique. A bandage lens supports early healing.

How similar are the results across the four techniques?

Surface ablation techniques have been compared in clinical studies, but a technique name alone does not predict your result. The correction required, the laser system, treatment planning and healing all matter. Discuss the expected vision, discomfort and recovery for the procedure recommended to you.

Early pain, epithelial healing time and haze findings can vary between techniques. The surgeon's choice depends on multiple factors, covered later on this page.

Who may be considered for surface ablation

Surface ablation may be considered when a LASIK flap is less desirable or when a patient's corneal or lifestyle profile suits a flapless approach. Suitability still depends on a full assessment, and the profiles below indicate reasons for considering surface ablation, not guarantees of eligibility.

When avoiding a LASIK flap may be appropriate

Surface ablation does not create a flap through the deeper supporting corneal tissue, called the stroma. For a comparable correction, it leaves a thicker layer of untouched corneal stroma than LASIK or SMILE. The risk of corneal ectasia, or progressive weakening and bulging of the cornea, is lower than with LASIK, but is not eliminated.^[2]

Surface ablation may therefore be preferred for selected patients with thinner corneas or slightly abnormal corneal scans. The surgeon must first assess whether these findings indicate corneal weakness or disease. Keratoconus, progressive thinning or insufficient healthy tissue may rule out corneal laser correction altogether. Detailed corneal shape and thickness measurements are essential.

As with other refractive procedures at AECS, patients are generally considered from age 21; those aged 18–21 may be assessed case by case if their prescription is stable. At AECS, surface ablation is usually not recommended for myopia stronger than −6.00 D, because of the increased risk of postoperative corneal haze or scarring.

Contact sports and occupations with a higher risk of eye trauma

Surface ablation does not create a new LASIK flap, so it avoids complications such as dislodgement or wrinkling of a newly created flap. This may be relevant for contact sports or occupations with a risk of eye injury. It does not make the eye injury-proof. If you previously had LASIK, the original flap remains even if surface ablation is used for an enhancement.

Dry eye or ocular surface considerations

Surface ablation may cause less postoperative dry eye than LASIK, which can make it an option for selected patients with dry eye concerns. It still affects the corneal surface and nerves, and dry eye symptoms can occur after either procedure. Existing dry eye disease is assessed and may need treatment before any corneal laser surgery is recommended.^[6]

Anatomical difficulty with flap creation

Eye shape and access to the cornea can affect which procedure is practical. For example, deep-set eyes or a narrow eyelid opening may make fitting a LASIK suction device more difficult. Surface ablation avoids that flap-creation step, but still needs sufficient access for treatment.

Previous laser vision correction

Surface ablation may be considered for an additional correction, called an enhancement, after LASIK or SMILE in selected patients. The section below explains what affects that decision.

Who may not be suitable

Surface ablation is not automatically suitable simply because LASIK has been ruled out. Some findings rule out corneal laser surgery altogether.

The following may make surface ablation unsuitable or require treatment to be postponed:

• A prescription that is still changing; the surgeon will confirm how long it needs to be stable
• Keratoconus, or scans suggesting a weak or progressively thinning cornea
• Insufficient corneal tissue for the planned ablation
• Active eye infection or significant ocular surface disease
• Certain autoimmune conditions, uncontrolled systemic disease, or medications that may interfere with healing
• Pregnancy or breastfeeding, because hormonal changes can shift the prescription
• Expectations that cannot reasonably be met by any laser vision correction procedure

Glasses and contact lenses remain alternatives. Selected patients may also be assessed for an implantable collamer lens (ICL), which corrects vision by adding a lens inside the eye. ICL has its own suitability requirements and surgical risks; it is not automatically appropriate when corneal laser surgery is unsuitable.

How the surgeon chooses a surface ablation technique

The choice between PRK, TransPRK, LASEK and Epi-LASIK is made after a full refractive assessment, not from the prescription alone. Several factors are considered together.

• Prescription and treatment depth. Larger corrections usually require more corneal tissue to be removed and may increase haze or the chance of some prescription returning. These factors may rule out corneal laser surgery altogether.
• Corneal shape and thickness. Scans show how regular and thick the cornea is and help assess whether the planned treatment is appropriate.
• Epithelial and ocular surface health. The condition of the tear film and epithelium can affect healing and comfort after surgery.
• Prior refractive surgery. Enhancements after earlier LASIK or SMILE are considered differently from primary treatments.
• Occupation and contact sport exposure. Long-term flap risk is one consideration when weighing surface ablation against LASIK.
• Ability to follow the postoperative regimen. Surface ablation may require a longer course of postoperative eye drops and follow-up than LASIK.
• Available laser platform. Different lasers support different technique workflows.
• Individual healing profile. Age, ultraviolet exposure and general health can influence the relative risks of haze, regression and delayed healing.

The procedure cannot be selected from prescription alone. A complete assessment is what makes the recommendation possible.

The surface ablation procedure

1. Before surgery: the refractive assessment

   A suitability assessment checks your prescription and its stability, corneal shape and thickness, tear film and surface health, and other aspects of eye health. Dilation is a routine part of the assessment, allowing the surgeon to examine the retina. Your surgeon uses the findings to decide whether surgery is appropriate.

   Contact lenses can temporarily alter corneal shape and affect measurements. Before your assessment at AECS, stop wearing soft contact lenses, including soft toric lenses, for one week, and hard contact lenses or orthokeratology (OK) lenses for three weeks. These intervals apply to AECS's refractive surgery assessments. Follow the clinic's instructions about lens wear before surgery; a longer break may be needed if measurements have not stabilised.

   Because dilation is routine, assessment and surgery are best arranged on separate days. Surgery may be scheduled as early as the next day if the surgeon confirms that you are suitable and the necessary arrangements are in place.

   A few practical notes:

   • Arrange transport to and from the assessment. If dilating drops are used, they can blur vision and increase light sensitivity for several hours. Bring sunglasses and do not drive until your vision is adequate for safe driving and the clinic's advice permits it.
   • Bring your current glasses or your latest prescription.
   • Allow enough time; the assessment includes multiple measurements plus a consultation.

   After the tests, the surgeon reviews the results with you and confirms whether surface ablation, or one of the alternative refractive procedures, is appropriate for your eyes. Detailed coverage of the shared assessment is on the LASIK page.

2. During surgery

   Numbing eye drops are placed in the eye before the procedure begins.

   A small device keeps the eyelids open. The surgeon removes or loosens the surface layer using the selected technique: a special instrument for conventional PRK, the excimer laser for TransPRK, diluted alcohol for LASEK, or a mechanical separator for Epi-LASIK.

   The excimer laser applies the planned treatment while you focus on a fixation light. The treatment time and whether both eyes are treated in the same session depend on the technique and individual treatment plan.

   Mitomycin C (MMC) may be applied briefly in selected cases to reduce the risk of corneal haze, or clouding during healing.^[5] Its use is individualised. A soft bandage contact lens is placed to protect the healing surface.

3. Immediately after surgery

   Vision is blurred initially and may fluctuate for days or weeks. Grittiness, watering, light sensitivity and soreness are common as the numbing drops wear off, often most noticeable over the first two to three days. Severe or increasing pain needs prompt advice.

   Use all prescribed eye drops and pain medication exactly as instructed by your surgeon.

   Do not remove or adjust the bandage lens yourself. If it falls out, do not reinsert it; contact the clinic. Do not drive on the day of surgery. Arrange for someone to take you home and follow the clinic's escort instructions.

Recovery timeline

Early recovery is generally slower than after LASIK. Plan time away from work while the corneal surface heals. Some patients manage daily activities within the first week, while others need longer. Vision may continue improving for weeks and stabilising over several months.^[3][4]

Recovery varies. Keep all scheduled reviews so the surgeon can check healing, vision, corneal clarity and eye pressure, particularly while steroid drops are used.

AECS's usual follow-up schedule is one day, one week, one month, three months and nine months after surgery. Additional reviews may be arranged according to your healing and the surgeon's advice.

Benefits and trade-offs

Surface ablation has potential benefits and corresponding trade-offs that should be considered before treatment.

Risks and possible complications

Surface ablation has been performed for several decades. Like any surgery, it can cause expected effects during healing and less common complications, which are separated below.

Expected during early healing

• Pain or discomfort, greatest during the first 48 to 72 hours
• Watering and light sensitivity
• Blurred or fluctuating vision
• Temporary dry eye symptoms
• Glare, haloes or reduced night vision quality during healing

Less common complications

• Infection during the epithelial healing period
• Delayed epithelial healing
• Corneal haze, where the cornea becomes less clear and vision may be affected
• An under-correction or over-correction, leaving a prescription that may still need glasses or further treatment
• Refractive regression, in which some of the correction returns over time
• Steroid-related elevation of eye pressure, which may require a change in medication or additional treatment
• Persistent ocular surface symptoms
• Reduced quality of vision, sometimes noticed at night
• Loss of vision that cannot be fully corrected with glasses
• Corneal ectasia, where weakening and progressive bulging of the cornea cause distorted vision and may require additional treatment

A 2021 review estimated lower reported rates of corneal ectasia after PRK than after LASIK, but cases occurred after both procedures.^[2] Its estimates were drawn from published reports and procedure-volume estimates, rather than a direct comparison of otherwise identical patients. They do not prove that PRK is suitable for a cornea that fails screening.

This is one reason preoperative topography and thickness measurements matter regardless of which procedure is being considered.

Corneal haze and Mitomycin C

Corneal haze is a wound-healing response that develops beneath the epithelium after surface ablation. It can reduce the clarity of the cornea. The risk of haze may be influenced by the depth of tissue removed, the size of the correction, ultraviolet exposure, previous corneal surgery, and how an individual eye heals.

Mitomycin C is a medicine used by some surgeons during selected surface ablation procedures to reduce the healing response associated with haze.^[5] It does not eliminate the risk. The surgeon decides whether it is appropriate and explains the relevant benefits and risks.

Use the prescribed eye drops and follow the surgeon's advice about ultraviolet protection, including sunglasses outdoors. Do not change steroid drops yourself; follow-up includes checks for side effects such as raised eye pressure.

Surface ablation after previous refractive surgery

Surface ablation may be considered for a remaining prescription after LASIK or SMILE. Before recommending an enhancement, the surgeon checks prescription stability, the original treatment, corneal thickness and shape, and whether the visual symptoms have another cause. An enhancement is not suitable for every patient.

After previous LASIK

An enhancement after LASIK may involve lifting the old flap, but this can allow surface cells to grow beneath it, known as epithelial ingrowth. Surface ablation on top of the healed flap is an alternative in selected cases. The old flap remains in the eye. The surgeon reviews the original surgery, current measurements and relevant risks before recommending an approach.

After previous SMILE

Surface ablation is one of several enhancement options after SMILE.^[7] The choice depends on the original treatment, remaining prescription, corneal measurements and available surgical methods.

Cost of surface ablation in Singapore

Surface ablation fees in Singapore vary between clinics, and the total cost depends on the specific technique, the technology used, the surgeon, and what is included in the fee.

What to check in the quoted fee

Ask AECS for a written estimate for the technique recommended after assessment, with a breakdown of the assessment, surgery and follow-up charges.

Check whether the quote is per eye or for both eyes, whether GST is included, and how medications, bandage lenses, follow-up visits and any enhancement are charged. Compare the total planned cost rather than the surgery fee alone.

MediSave and insurance

Elective laser vision correction to reduce dependence on glasses is generally not eligible for MediSave. Any proposed exception for a medical indication needs confirmation under the applicable rules; a high prescription or being unsuitable for LASIK does not by itself confirm eligibility.

Ask the clinic's billing team to confirm eligibility before relying on a claim. Do not assume that MediSave rules and insurance coverage are the same.

Insurance benefits depend on the policy. If your employer or insurer offers a laser vision correction benefit, check the approved providers, limits and pre-authorisation requirements before treatment.

Surface ablation compared with LASIK, SMILE and ICL

Surface ablation, LASIK, SMILE and ICL use different approaches to vision correction. The comparison below explains the main differences; it does not establish which procedure is suitable for you.

Why consider AECS for surface ablation

Refractive surgery at Advanced Eye Clinic & Surgery is planned and performed by senior consultant ophthalmologists with refractive surgery experience. The surgeon who assesses your eyes plans your treatment and reviews you afterwards.

AECS's treatment options cover LASIK, SMILE, surface ablation and ICL. Your surgeon can discuss the options appropriate to your eye measurements and needs.

Having both corneal and lens-based options available allows the surgeon to compare different approaches after reviewing your eye measurements, prescription and lifestyle needs.

Our refractive surgeons

Dr Chua Wei Han

Founder, Medical Director and Senior Consultant Ophthalmologist

BMedSc (Hons), BMed (Hons), MMed (Ophth), FRCSEd (Ophth), FAMS

Dr Chua founded Advanced Eye Clinic & Surgery and sub-specialises in cataract and refractive surgery. His published profile includes LASIK, SMILE, surface ablation and ICL. Surface ablation uses an excimer laser; ICL involves implanting a lens inside the eye.

He graduated with honours from the University of Newcastle, Australia, and is a Fellow of the Royal College of Surgeons of Edinburgh and the Academy of Medicine, Singapore. He has presented at more than 100 international scientific meetings, published over 25 peer-reviewed papers spanning refractive errors, LASIK and dry eye treatment, and has served as an investigator in US FDA clinical trials.

View full profile · Book with Dr Chua

Dr Mohamad Rosman

Senior Consultant Ophthalmologist

MBBS (NUS, Valedictorian), MMed (Ophth), FRCS (Edinburgh), FAMS

Dr Rosman was Head of the Refractive Surgery Department at the Singapore National Eye Centre for nine years, where he was in charge of the Laser Vision Centre and was involved in training ophthalmologists in LASIK, SMILE, ICL, surface ablation and cataract surgery. He has published peer-reviewed articles and book chapters on refractive surgery, and is a regular speaker at local and international refractive surgery meetings.

Dr Rosman's published profile reports more than 20,000 cataract, LASIK and other eye operations across his career. He completed refractive surgery fellowships at SNEC and the VISSUM Eye Institute in Spain. He consults in English, Mandarin, Malay and Bahasa Indonesia.

View full profile · Book with Dr Rosman

Frequently asked questions

Selected references