PRK Eye Surgery: Suitability, Procedure, Risks and Recovery

Author: Dr Val Phua
Estimated reading time: 21 minutes

Photorefractive keratectomy, or PRK, is a laser vision-correction procedure used to reduce dependence on spectacles or contact lenses.

During PRK:

• The thin surface layer of the cornea—the epithelium—is removed.
• An excimer laser precisely reshapes the underlying corneal tissue.
• A protective bandage contact lens is placed over the eye.
• The epithelium grows back naturally over the following several days.

Unlike LASIK, PRK does not create a permanent corneal flap.

PRK can treat selected patients with:

• Myopia, or short-sightedness
• Hyperopia, or long-sightedness
• Regular astigmatism
• Presbyopia through monovision in appropriately counselled patients
• Residual refractive error after selected previous eye procedures

PRK generally provides visual outcomes comparable to LASIK once healing is complete. Its principal disadvantages are greater discomfort during the first few days and a slower visual recovery. Its advantages include the absence of a corneal flap and preservation of more residual stromal tissue than an equivalent LASIK treatment.

PRK may therefore be considered for patients who:

• Have a relatively thin cornea
• Participate in contact sports
• Have an occupation involving facial trauma
• Wish to avoid a permanent LASIK flap
• Have superficial corneal irregularity
• Require treatment over a previous LASIK flap
• Are unsuitable for LASIK but remain suitable for surface laser treatment

However, PRK is not automatically safe simply because no flap is created.

Possible complications include:

• Postoperative pain
• Slow epithelial healing
• Infection
• Corneal haze
• Dry eye
• Glare and halos
• Under-correction or over-correction
• Residual astigmatism
• Regression
• Corneal scarring
• Corneal ectasia
• Rare loss of corrected vision

The most important factor is not the name of the procedure. It is whether the cornea is structurally suitable for laser treatment at all.

The Quick Answer

What Is PRK?

PRK is a surface laser procedure that reshapes the cornea without creating a LASIK flap.

The surface epithelium is removed before an excimer laser is applied to the corneal stroma.

The epithelium normally grows back beneath a bandage contact lens.

What Does PRK Treat?

PRK may correct:

• Short-sightedness
• Long-sightedness
• Regular astigmatism
• Selected residual prescriptions after previous surgery
• Presbyopia using monovision in suitable patients

The treatable range depends on:

• Corneal thickness
• Corneal shape
• Prescription
• Ablation depth
• Planned optical zone
• Expected residual stromal tissue
• Laser platform
• Local regulatory approval
• The surgeon’s assessment

Is PRK Painful?

PRK is generally not painful during the procedure because anaesthetic eye drops are used.

Discomfort usually develops after the anaesthetic wears off.

During the first two to four days, patients may experience:

• Burning
• Stinging
• Watering
• Grittiness
• Light sensitivity
• Difficulty opening the eyes
• A foreign-body sensation
• Fluctuating pain

Pain is usually most noticeable during the first 24 to 48 hours and improves as the epithelium heals.

Bandage contact lenses, oral pain medication, topical non-steroidal anti-inflammatory medication and cold therapy may reduce postoperative discomfort. The American Academy of Ophthalmology’s evidence review found support for several of these approaches, although the exact regimen should be individualised.

How Long Does PRK Take?

The procedure commonly takes approximately 10 to 20 minutes for both eyes.

The actual excimer-laser treatment may last only seconds, depending on:

• Prescription
• Optical-zone size
• Laser speed
• Treatment profile

Additional time is required for:

• Preparation
• Sterile cleaning
• Epithelial removal
• Laser alignment
• Mitomycin C when indicated
• Bandage contact-lens placement
• Postoperative examination

How Quickly Does Vision Recover?

Vision is usually blurry during the first several days.

Functional recovery commonly progresses over:

• Several days for basic indoor activity
• One to two weeks for improved functional vision
• Several weeks for sharper distance vision
• One to three months for greater stability
• Occasionally longer for higher prescriptions or irregular treatments

PRK therefore requires more recovery time than LASIK.

Is PRK Permanent?

The corneal tissue removed by the excimer laser does not grow back in its original form.

However, the eye may still change because of:

• Continuing myopia
• Epithelial remodelling
• Corneal healing
• Presbyopia
• Cataract development
• Diabetes-related refractive fluctuation
• Age-related changes

Long-term studies demonstrate that PRK can remain effective for many years, although regression is more likely after higher corrections and with older treatment technologies.

Will I Never Need Spectacles Again?

Not necessarily.

Spectacles may still be needed for:

• Fine reading
• Night driving
• A small residual prescription
• Presbyopia
• Tasks requiring maximum visual precision
• Future cataract-related changes
• Progressive myopia

The aim is usually to reduce dependence on spectacles or contact lenses rather than guarantee complete lifelong independence.

Understanding Refractive Error

Myopia

Myopia occurs when light focuses in front of the retina.

Patients usually see near objects more clearly than distant objects.

Myopic PRK flattens the central cornea to reduce its focusing power.

Hyperopia

Hyperopia occurs when the eye has insufficient focusing power or is relatively short.

Hyperopic PRK steepens the central cornea by removing tissue in a surrounding pattern.

Hyperopic treatments may be more sensitive to:

• Treatment centration
• Pupil size
• Latent hyperopia
• Age-related change
• Regression

Astigmatism

Astigmatism occurs when the cornea has different curvature in different directions.

The excimer laser applies an asymmetric treatment to reduce the difference between the principal corneal meridians.

Accurate astigmatism correction depends on:

• Reliable refraction
• Corneal regularity
• Axis alignment
• Cyclotorsion compensation
• Eye tracking
• Treatment centration
• Healing response

Presbyopia

Presbyopia is the age-related loss of the natural lens’s ability to focus at near.

PRK reshapes the cornea but does not restore the flexibility of the natural lens.

A patient with clear distance vision after PRK will still develop presbyopia with age.

Monovision PRK

Monovision is a strategy in which:

• One eye is treated primarily for distance.
• The other eye is left mildly short-sighted for intermediate or near vision.

This may reduce dependence on reading spectacles.

Possible disadvantages include:

• Reduced depth perception
• Reduced stereoacuity
• Reduced binocular distance sharpness
• Night-driving difficulty
• Difficulty adapting

A contact-lens monovision trial is often helpful before permanent surgery.

Who May Be Suitable for PRK?

A suitable patient generally has:

• A stable spectacle prescription
• Healthy corneal shape
• Adequate corneal thickness
• No evidence of keratoconus
• No corneal ectasia
• A manageable degree of refractive error
• A sufficiently healthy ocular surface
• No visually significant cataract
• No uncontrolled eye disease
• Realistic expectations
• The ability to attend postoperative reviews

How Stable Must the Prescription Be?

The prescription should generally remain stable for at least approximately one year.

A small change does not automatically exclude treatment, but continuing progression increases the chance that the result will not remain accurate.

Instability may occur with:

• Younger age
• Progressive myopia
• Pregnancy
• Breastfeeding
• Poorly controlled diabetes
• Hormonal change
• Certain medication
• Early cataract

Is There a Minimum Age?

PRK is generally not performed below 18 years of age.

Reaching 18 does not automatically mean that the prescription is stable.

Many young adults continue to experience myopic progression.

Is There a Maximum Age?

There is no universal maximum age.

Older patients require careful assessment for:

• Presbyopia
• Early cataract
• Dry eye
• Glaucoma
• Macular degeneration
• Corneal endothelial disease
• Expectations regarding near vision

If early cataract or significant lens-related refractive change is present, cataract surgery may offer a more appropriate long-term solution.

Why Might PRK Be Recommended Instead of LASIK?

PRK may be favoured when:

• The cornea is relatively thin
• Preserving more residual stromal tissue is desirable
• The patient participates in contact sports
• A permanent flap would be occupationally undesirable
• There is superficial corneal scarring
• There is epithelial basement membrane dystrophy
• A previous LASIK flap is present
• Flap creation would be technically difficult
• The patient strongly prefers a flap-free option

PRK removes the epithelium and ablates the anterior stroma. LASIK creates a flap before performing a stromal ablation. Avoiding the flap usually leaves a larger load-bearing residual stromal bed for an equivalent refractive correction.

This does not mean that PRK makes an abnormal cornea safe to treat.

Who May Not Be Suitable for PRK?

PRK may be inappropriate or require special caution in the presence of:

• Keratoconus
• Suspicious corneal tomography
• Corneal ectasia
• Insufficient corneal thickness
• Unstable refraction
• Severe dry eye
• Active blepharitis
• Active corneal infection
• Previous herpetic keratitis
• Uncontrolled glaucoma
• Active uveitis
• Visually significant cataract
• Poorly controlled diabetes
• Active autoimmune disease
• Poor wound healing
• Pregnancy or breastfeeding
• Unrealistic expectations
• Inability to attend close follow-up

Pregnancy and Breastfeeding

Elective PRK is generally postponed during pregnancy and breastfeeding.

Reasons include:

• Refractive fluctuation
• Corneal-curvature changes
• Tear-film instability
• Medication considerations
• Hormonal effects on healing

Measurements should be repeated after the prescription and ocular surface have stabilised.

Diabetes

Well-controlled diabetes does not automatically exclude every patient.

Suitability depends on:

• Stability of blood glucose
• Stability of refraction
• Presence of diabetic retinopathy
• Corneal sensation
• Dry-eye status
• Wound healing
• General health

Poorly controlled diabetes may cause:

• Fluctuating vision
• Slow epithelial healing
• Infection risk
• Less predictable results

Autoimmune and Connective-Tissue Disease

Active or poorly controlled autoimmune disease may increase the risk of:

• Severe dry eye
• Delayed healing
• Corneal inflammation
• Infection
• Corneal melting
• Unpredictable refractive outcomes

Stable systemic disease requires individual assessment and, where appropriate, discussion with the treating physician.

Contact Lenses Before Assessment

Contact lenses may temporarily alter corneal shape.

They should be stopped before definitive measurements.

The required interval depends on:

• Soft or rigid lens use
• Duration of wear
• Orthokeratology
• Corneal warpage
• Repeat measurement stability

Rigid gas-permeable and orthokeratology lenses may require a longer period of discontinuation than ordinary soft lenses.

The Pre-PRK Assessment

The assessment must determine:

• Whether the refractive error can be treated accurately
• Whether the cornea can be treated safely
• Whether PRK is preferable to LASIK, SMILE or ICL
• Whether the ocular surface can heal normally
• Whether the patient accepts the recovery period

Medical and Ocular History

Important information includes:

• Previous eye surgery
• Contact-lens use
• Dry eye
• Recurrent corneal erosion
• Eye rubbing
• Corneal infection
• Herpetic eye disease
• Glaucoma
• Retinal disease
• Diabetes
• Autoimmune disease
• Keloid or abnormal scarring history
• Pregnancy plans
• Medication
• Occupational requirements
• Contact sports

Visual-Acuity Testing

Both unaided and corrected vision are measured.

The corrected vision helps define the eye’s visual potential.

PRK cannot correct reduced vision caused by:

• Amblyopia
• Retinal disease
• Optic-nerve damage
• Corneal scarring
• Neurological disease

Manifest Refraction

The subjective spectacle prescription is measured carefully.

This may be repeated because small errors can affect:

• Treatment depth
• Astigmatism correction
• Refractive accuracy
• Binocular balance

Cycloplegic Refraction

Dilating drops temporarily relax accommodation.

This may be helpful for:

• Younger patients
• Hyperopia
• Accommodative spasm
• Inconsistent measurements
• Avoiding excessive myopic treatment

Corneal Topography

Topography maps the shape of the front corneal surface.

It helps identify:

• Regular astigmatism
• Irregular astigmatism
• Contact-lens warpage
• Decentration
• Keratoconus-like patterns
• Previous treatment zones

Corneal Tomography

Tomography analyses the three-dimensional corneal structure.

It may assess:

• Anterior elevation
• Posterior elevation
• Corneal thickness
• Thickness distribution
• Corneal curvature
• Ectasia-risk indices
• Corneal volume

A patient can have good corrected vision and still have early keratoconus.

Normal letter-chart vision is therefore not sufficient to establish suitability.

Pachymetry

Pachymetry measures corneal thickness.

The surgeon considers:

• Starting corneal thickness
• Planned ablation depth
• Residual stromal thickness
• Percentage of tissue altered
• Corneal shape
• Age
• Prescription
• Optical-zone size

There is no single thickness number that automatically makes PRK safe or unsafe.

Epithelial Thickness Mapping

The epithelium may redistribute itself to mask an underlying stromal irregularity.

Epithelial mapping may help identify:

• Early keratoconus
• Contact-lens warpage
• Epithelial compensation
• Irregular corneal shape
• Previous ablation patterns

Wavefront Aberrometry

Wavefront testing measures optical aberrations passing through the eye.

It may identify:

• Defocus
• Astigmatism
• Coma
• Spherical aberration
• Other higher-order aberrations

The information may be used in selected wavefront-guided treatments.

Tear-Film and Dry-Eye Assessment

The ocular surface is assessed for:

• Tear-film instability
• Corneal staining
• Conjunctival staining
• Meibomian gland dysfunction
• Blepharitis
• Reduced tear production
• Contact-lens-related inflammation

Dry eye should be treated before surgery.

An unstable tear film can affect:

• Refraction
• Corneal topography
• Laser planning
• Postoperative comfort
• Visual quality

Pupil and Centration Assessment

The surgeon may assess:

• Pupil size
• Pupil centre
• Visual axis
• Corneal vertex
• Fixation
• Angle kappa

Treatment centration and optical-zone planning may influence:

• Night vision
• Glare
• Halos
• Coma
• Ghosting

Eye-Pressure Measurement

Eye pressure is measured to assess glaucoma risk.

After PRK, conventional pressure readings may appear artificially lower because the cornea has become thinner and flatter.

Future eye-care providers should be informed about the refractive surgery.

Dilated Retinal Examination

The retina and optic nerve may be examined for:

• Retinal holes
• Retinal tears
• Lattice degeneration
• Myopic macular changes
• Glaucoma
• Retinal detachment
• Other causes of reduced vision

Correcting myopia does not remove the retinal risks associated with a long, highly myopic eye.

How Is PRK Performed?

Step 1: Confirming the Treatment

Before surgery, the team confirms:

• Patient identity
• Correct eye
• Prescription
• Treatment profile
• Laser calibration
• Corneal measurements
• Astigmatism axis

Step 2: Anaesthetic Drops

Anaesthetic drops numb the cornea.

The skin and eyelids are cleaned.

A small instrument keeps the eyelids open.

The patient does not need to worry about blinking.

Step 3: Removing the Epithelium

The central corneal epithelium is removed.

Possible techniques include:

• Mechanical removal
• Alcohol-assisted removal
• Brush-assisted removal
• Transepithelial laser removal

The intended outcome is to expose the anterior corneal stroma for excimer-laser treatment.

Step 4: Excimer-Laser Reshaping

The patient looks towards a fixation light.

The excimer laser removes microscopic amounts of stromal tissue.

The laser may use:

• Eye tracking
• Cyclotorsion compensation
• Wavefront optimisation
• Wavefront guidance
• Topography guidance
• Custom optical-zone planning

The excimer laser reshapes tissue through photoablation rather than thermal burning.

Step 5: Mitomycin C When Indicated

Mitomycin C may be applied briefly to the treated corneal surface in selected patients.

It is used to reduce the activity of stromal cells involved in corneal haze formation.

The concentration and exposure time vary according to:

• Ablation depth
• Prescription
• Previous corneal surgery
• Haze risk
• Surgeon protocol

Meta-analysis supports a reduction in haze with mitomycin C, particularly in higher-risk treatments. However, it is a potent medication and should not be applied indiscriminately.

Some clinical studies have reported endothelial-cell loss associated with longer mitomycin C exposure, while other long-term series have found good outcomes using controlled protocols. The surgeon should use the lowest appropriate exposure based on the individual treatment.

Step 6: Irrigating the Cornea

The cornea is rinsed with sterile fluid.

This removes:

• Residual medication
• Tissue debris
• Loose epithelial cells

Step 7: Placing the Bandage Contact Lens

A soft bandage contact lens is placed over the cornea.

It:

• Protects exposed nerve endings
• Reduces eyelid friction
• Supports epithelial healing
• Improves comfort

The contact lens remains in place until the epithelium has healed sufficiently.

Step 8: Final Examination

The surgeon checks:

• Treatment centration
• Corneal surface
• Bandage lens position
• Absence of significant debris
• Immediate postoperative appearance

No stitches are usually required.

Can Both Eyes Be Treated Together?

Yes.

Bilateral same-day PRK is common.

Advantages include:

• One recovery period
• Reduced binocular imbalance
• Fewer separate procedure visits

The disadvantage is that both eyes may be uncomfortable and blurry at the same time during the first few days.

Patients may need assistance with:

• Transport
• Meals
• Childcare
• Medication
• Daily activities

What Is TransPRK?

Transepithelial PRK uses the excimer laser to remove the epithelium and perform the refractive stromal treatment.

It is sometimes described as:

• No-touch PRK
• Single-step TransPRK
• Transepithelial surface ablation

The exact technique depends on the laser platform.

Is TransPRK Better Than Conventional PRK?

TransPRK may offer:

• Less mechanical contact
• A standardised epithelial-removal profile
• Shorter procedural handling
• Reduced instrument manipulation
• Potentially less early discomfort on some platforms

However, the epithelium varies in thickness between patients and across the cornea.

Randomised studies have not shown universal superiority of TransPRK for every measure. One contralateral-eye trial found similar healing times between transepithelial, mechanical and alcohol-assisted methods, while a more recent randomised study reported comparable refractive outcomes with differences in patient experience and early recovery.

A 2026 meta-analysis found no significant overall difference in efficacy or predictability between TransPRK and LASIK or SMILE, although individual subgroup results and recovery characteristics varied. Procedure selection should be based on the patient, platform and surgeon rather than the label alone.

Wavefront-Optimised PRK

Wavefront-optimised treatment is designed to reduce the induction of spherical aberration.

It does not use a fully individualised measurement of every higher-order aberration.

Wavefront-Guided PRK

Wavefront-guided PRK incorporates optical measurements from the entire eye.

It may be considered when:

• Measurements are repeatable
• Higher-order aberrations are clinically relevant
• Iris registration is suitable
• The platform supports the treatment

Topography-Guided PRK

Topography-guided PRK is based primarily on corneal-shape measurements.

It may be used to:

• Regularise corneal optics
• Improve treatment centration
• Reduce selected corneal asymmetry
• Treat refractive error
• Manage selected irregular corneas

The treatment plan may combine topographic regularisation with refractive correction.

What Happens Immediately After PRK?

After the anaesthetic wears off, the eyes may feel:

• Painful
• Gritty
• Watery
• Sensitive to light
• Difficult to open
• Hazy

Symptoms are often most significant during the first one or two days.

The patient should go home, rest and follow the prescribed medication schedule.

Eye Drops After PRK

Medication may include:

• Antibiotic drops
• Steroid drops
• Preservative-free lubricants
• Non-steroidal anti-inflammatory drops
• Cycloplegic drops in selected patients
• Other pain-control medication

The exact regimen varies.

Patients should:

• Wash their hands
• Avoid touching the bottle tip to the eye
• Use drops according to schedule
• Space different drops apart
• Avoid stopping steroid medication without advice

The Bandage Contact Lens

The bandage lens is usually left in place until the epithelium has closed.

This commonly takes approximately three to five days, although healing varies.

The lens may remain longer when:

• Healing is incomplete
• The epithelial edge remains unstable
• The surface has irregularity
• The patient has another healing risk

A randomised trial comparing removal on day four and day seven found no important long-term difference by three months, although early visual findings varied. Removal should therefore be based on clinical healing rather than a rigid timetable.

Can I Remove the Bandage Lens Myself?

No.

The bandage contact lens should be removed by the eye-care team.

Removing it too early may:

• Disrupt the healing epithelium
• Increase pain
• Delay recovery
• Increase infection risk

If the lens falls out, contact the clinic rather than replacing it yourself.

The First 24 Hours

Possible symptoms include:

• Significant watering
• Burning
• Light sensitivity
• Blurred vision
• Eyelid swelling
• Difficulty keeping the eyes open
• Fluctuating pain

Pain medication should be taken according to the prescribed plan.

Days Two to Four

Discomfort commonly improves as the epithelial defect becomes smaller.

Vision may remain:

• Hazy
• Fluctuating
• Sensitive to light
• Unequal between the two eyes

The patient should continue all prescribed drops.

After Bandage-Lens Removal

The surface may still feel:

• Dry
• Mildly gritty
• Sensitive
• Variable between blinks

Vision does not become instantly sharp simply because the epithelium has closed.

The new epithelium remains immature and irregular initially.

The First Week

Many patients can perform basic daily activities, but vision may not yet be suitable for:

• Driving
• Detailed computer work
• Night work
• Fine visual tasks
• Hazardous occupations

The First Month

Vision usually becomes progressively clearer.

Temporary symptoms may include:

• Dryness
• Glare
• Halos
• Ghosting
• Fluctuation
• Reduced contrast
• Mild haze

Three to Six Months

The corneal surface, epithelium, stromal healing and nerves continue to stabilise.

Higher corrections and customised treatments may take longer to reach their final result.

When Can I Return to Work?

This depends on:

• Occupation
• Visual requirements
• Pain
• Light sensitivity
• Computer use
• Dust exposure
• Need to drive
• Whether both eyes were treated

Some patients return to desk work within approximately one week.

Others require longer.

Can I Use a Computer or Phone?

Yes.

Screens do not damage the cornea or reverse the laser treatment.

However, screen use reduces blinking and may worsen:

• Dryness
• Burning
• Fluctuating vision
• Eye fatigue

Frequent breaks and lubricating drops may help.

When Can I Drive?

Driving should resume only when:

• Vision meets the legal requirement
• The patient feels confident
• Glare is manageable
• Depth perception is satisfactory
• The surgeon has not advised otherwise

The patient should not drive home after surgery.

When Can I Exercise?

Gentle walking is usually possible early.

Strenuous activity may be restricted temporarily.

The patient should avoid:

• Sweat entering the eye
• Eye rubbing
• Dust
• Direct trauma
• Contact sports

When Can I Swim?

Swimming is generally avoided during the early healing period.

Pool, sea and spa water may contain:

• Bacteria
• Parasites
• Chemicals
• Irritants

The surgeon should provide a specific timeline.

When Can I Wear Eye Makeup?

Eye makeup should be avoided during early healing.

Old mascara, eyeliner and applicators may be contaminated.

When Can I Fly?

Uncomplicated PRK does not place a gas bubble inside the eye and usually does not prohibit flying.

However:

• Aircraft cabins may worsen dryness.
• Early postoperative reviews must not be missed.
• Access to urgent eye care should be considered.

Expected Visual Results

Modern PRK can produce excellent unaided vision in appropriately selected patients.

Once recovery is complete, refractive outcomes are generally comparable to LASIK in low-to-moderate myopia. LASIK offers faster initial visual recovery, while PRK avoids flap-related complications.

Outcomes depend on:

• Prescription
• Corneal shape
• Laser technology
• Treatment profile
• Healing response
• Dry-eye status
• Patient age
• Surgeon nomogram

Is 20/20 the Same as Perfect Vision?

No.

A high-contrast visual-acuity chart does not fully measure:

• Contrast sensitivity
• Night vision
• Glare
• Halos
• Starbursts
• Ghost images
• Tear-film fluctuation
• Visual comfort

A patient may read 20/20 and still notice optical symptoms.

How Long Does the Result Remain Stable?

Long-term studies show that PRK can remain safe and effective for more than ten years.

However, older studies involving high myopia reported:

• Greater regression
• Lower predictability
• Higher retreatment rates

These findings partly reflect earlier laser technology, smaller optical zones and older nomograms. They remain relevant because they demonstrate that high corrections are biologically less predictable over time.

Dry Eye After PRK

PRK can cause temporary dry eye because it disrupts:

• Corneal nerves
• Corneal sensation
• Reflex tearing
• Blinking
• Tear-film regulation

Possible symptoms include:

• Burning
• Grittiness
• Fluctuating vision
• Redness
• Light sensitivity
• Tired eyes
• Excessive tearing

Is Dry Eye Less Common Than After LASIK?

PRK does not create a flap and generally disrupts fewer deeper corneal nerves than LASIK.

Dry-eye symptoms may therefore be less persistent on average after surface ablation, although PRK still causes substantial early surface injury.

A prospective study found that corneal subbasal nerve density returned towards preoperative levels earlier after PRK than after LASIK. Nerve density was not significantly different from baseline by approximately two years after PRK, compared with approximately five years after LASIK in that cohort.

Individual patients may still develop prolonged dry eye or neuropathic symptoms.

Treating Dry Eye

Management may include:

• Preservative-free artificial tears
• Lubricating gel
• Warm compresses
• Lid hygiene
• Treatment of meibomian gland dysfunction
• Anti-inflammatory eye drops
• Punctal plugs
• Autologous serum
• Scleral lenses in severe cases

Corneal Haze

Corneal haze is abnormal stromal scarring or light scatter that may develop after surface ablation.

It may appear as:

• Fine subepithelial clouding
• Grey opacity
• Irregular stromal reflectivity
• Dense scarring in severe cases

What Causes Haze?

PRK triggers a wound-healing response.

Factors involved may include:

• Epithelial injury
• Release of inflammatory mediators
• Keratocyte activation
• Myofibroblast formation
• Disorganised extracellular matrix
• Ultraviolet exposure
• Deep ablation
• Delayed epithelial healing

Who Is at Greater Risk of Haze?

Risk may be higher with:

• High myopic correction
• Deep stromal ablation
• Previous corneal surgery
• Slow epithelial healing
• Excessive ultraviolet exposure
• Infection
• Significant inflammation
• Poor steroid adherence
• Certain individual healing responses

When Does Haze Develop?

Haze may become noticeable:

• Within several weeks
• During the first few months
• Occasionally later

Mild early haze may improve gradually.

Dense late haze can cause:

• Blurred vision
• Glare
• Reduced contrast
• Irregular astigmatism
• Loss of corrected vision

Preventing Haze

Prevention may include:

• Appropriate patient selection
• Avoiding excessive treatment depth
• Smooth laser ablation
• Mitomycin C when indicated
• Controlled steroid treatment
• Good epithelial healing
• Ultraviolet protection
• Prompt treatment of inflammation or infection

Ultraviolet Protection

Patients are commonly advised to wear good-quality ultraviolet-blocking sunglasses outdoors during the early postoperative months.

This is particularly important in:

• Sunny climates
• High-altitude environments
• Patients undergoing deeper ablations
• Patients with previous haze

Sunglasses do not replace prescribed medication.

Treating Corneal Haze

Treatment depends on severity.

Options may include:

• Steroid eye drops
• Lubrication
• Treatment of ocular-surface inflammation
• Observation for mild improving haze
• Phototherapeutic keratectomy
• Topography-guided surface treatment
• Mitomycin C during retreatment
• Corneal transplantation in extremely severe cases

Under-Correction and Over-Correction

The achieved result may differ from the intended target.

Possible causes include:

• Measurement variation
• Biological healing
• Epithelial remodelling
• Laser-tissue interaction
• Treatment centration
• Higher prescription
• Astigmatic-axis error
• Dry eye

Management may include:

• Observation
• Spectacles
• Contact lenses
• Enhancement
• Ocular-surface treatment

Regression

Regression means that part of the original refractive error returns.

Possible contributors include:

• Higher preoperative myopia
• Epithelial thickening
• Stromal remodelling
• Continuing axial elongation
• Age-related lens change
• Inadequate optical-zone size
• Individual wound healing

Enhancement After PRK

An enhancement may be considered when:

• A meaningful residual prescription remains
• The prescription is stable
• The cornea remains structurally suitable
• Haze is absent or manageable
• The ocular surface is healthy
• The expected benefit exceeds the additional risk

A repeat surface ablation may be performed in selected patients.

How Long Before an Enhancement?

The result should be stable.

This commonly requires several months and may require longer when:

• The original prescription was high
• Healing remains active
• Haze is present
• Dry eye persists
• Refraction continues changing

An enhancement should not be rushed while the cornea is still remodelling.

Slow Epithelial Healing

The epithelium normally closes within several days.

Healing may be slower in patients with:

• Diabetes
• Severe dry eye
• Corneal dystrophy
• Older age
• Previous corneal surgery
• Medication toxicity
• Infection
• Poor ocular-surface health

Slow healing increases the risk of:

• Pain
• Infection
• Haze
• Scarring
• Irregular epithelium

Recurrent Corneal Erosion

The new epithelium usually attaches securely.

Rarely, patients may develop recurrent episodes of:

• Sudden pain on waking
• Watering
• Light sensitivity
• Foreign-body sensation
• Blurred vision

This may indicate recurrent corneal erosion.

Treatment may include:

• Lubricating ointment
• Hypertonic saline
• Bandage contact lens
• Oral doxycycline
• Anti-inflammatory treatment
• Further surface procedures

Infection

Infectious keratitis after PRK is uncommon but potentially sight-threatening.

The corneal surface remains vulnerable while the epithelium is open and a bandage contact lens is present.

Warning signs include:

• Increasing pain
• Increasing redness
• Worsening vision
• Thick discharge
• Marked light sensitivity
• A white corneal spot
• Symptoms worsening after initial improvement

Urgent antimicrobial treatment is required.

Sterile Infiltrates

Not every white corneal spot is an infection.

Sterile inflammatory infiltrates may also occur.

However, infection must be excluded urgently because delayed treatment can cause permanent scarring.

Corneal Ectasia

Corneal ectasia is progressive thinning and bulging of the cornea.

It may cause:

• Increasing myopia
• Increasing astigmatism
• Ghosting
• Reduced corrected vision
• Irregular corneal shape
• Contact-lens dependence

Is Ectasia Less Common After PRK Than LASIK?

Reported ectasia appears less common after PRK than after LASIK.

A systematic review estimated substantially fewer reported cases after PRK than LASIK, although the true incidence is difficult to determine because of differences in follow-up, reporting and patient selection. Pre-existing keratoconus or suspicious corneal shape remains one of the most important risk factors.

PRK must not be used as a way to treat a structurally unsuitable cornea simply because it avoids a flap.

Risk Factors for Ectasia

Possible risk factors include:

• Keratoconus
• Suspicious tomography
• Abnormal posterior elevation
• Abnormal thickness distribution
• Young age
• High tissue removal
• Thin residual stroma
• Eye rubbing
• Family history
• Progressive corneal asymmetry

Treating Ectasia

Treatment may include:

• Corneal cross-linking
• Spectacles
• Rigid contact lenses
• Scleral lenses
• Intracorneal ring segments
• Specialised topography-guided treatment
• Corneal transplantation in advanced cases

Loss of Corrected Vision

Rarely, an eye may not see as clearly with spectacles after PRK as it did before surgery.

Possible causes include:

• Haze
• Scarring
• Infection
• Irregular astigmatism
• Ectasia
• Decentration
• Severe dry eye
• Retinal or optic-nerve disease

Modern PRK is generally safe in properly selected patients, but the risk cannot be reduced to zero.

Night-Vision Symptoms

Possible symptoms include:

• Halos
• Glare
• Starbursts
• Ghost images
• Smearing around lights
• Reduced contrast

These may be related to:

• Dry eye
• Residual refractive error
• Higher-order aberrations
• Large pupils
• Optical-zone size
• Decentration
• Haze
• Healing

Symptoms often improve as the surface stabilises.

Corneal Nerve Recovery

The surface nerves are removed or damaged during epithelial removal and stromal ablation.

They regenerate gradually.

Confocal-microscopy studies show substantial neural recovery over time after PRK, although microscopic corneal changes may remain detectable for years without necessarily impairing visual performance.

PRK Versus LASIK

Both procedures use an excimer laser to reshape the corneal stroma.

Possible Advantages of PRK

• No permanent flap
• No flap displacement
• No flap striae
• No flap-interface epithelial ingrowth
• Larger residual stromal bed for an equivalent correction
• May suit thinner corneas
• May suit contact-sport participants
• May suit selected superficial corneal abnormalities

Possible Advantages of LASIK

• Faster visual recovery
• Less early pain
• Faster return to work
• Lower risk of surface haze
• Easier enhancement through flap relifting

Limitations of PRK

• More postoperative discomfort
• Slower recovery
• Bandage contact lens
• Risk of haze
• Longer steroid course
• Greater early fluctuation

Randomised comparative studies show that LASIK recovers faster, while longer-term efficacy can be similar. One paired-eye trial using mitomycin C found excellent one-year outcomes after both procedures and no clinically significant haze in the PRK eyes.

PRK Versus SMILE

SMILE removes a femtosecond-laser-created stromal lenticule through a small incision.

Possible Advantages of PRK

• No flap
• No internal cap-to-lenticule dissection
• Greater availability of wavefront- and topography-guided profiles
• Straightforward surface enhancement
• May suit selected lower prescriptions and irregular corneal treatments

Possible Advantages of SMILE

• Less early pain
• Faster epithelial recovery
• Faster functional visual recovery
• Lower risk of surface haze
• No large epithelial defect

Limitations of SMILE

• More complex enhancement options
• Less customisation on some platforms
• Lenticule-dissection complications
• Primarily established for myopia and myopic astigmatism

A recent meta-analysis found broadly comparable final efficacy and predictability between TransPRK and SMILE, although recovery, pain, optical profiles and complication patterns differ.

PRK Versus ICL

An implantable collamer lens is placed inside the eye without removing the natural lens.

Possible Advantages of PRK

• No intraocular implant
• No intraocular surgery
• No ICL sizing or vault issues
• No ICL-related cataract risk
• No long-term intraocular-lens monitoring

Possible Advantages of ICL

• No corneal stromal tissue removal
• Suitable for higher myopia
• Often excellent optical quality
• Removable or exchangeable
• Useful when corneal laser treatment is unsafe

ICL may be preferable when:

• The prescription is high
• The cornea is thin
• The treatment would require excessive stromal removal
• The corneal shape is unsuitable for laser ablation
• Optical-quality preservation is a major priority

A 2026 network meta-analysis found that ICL produced fewer higher-order aberrations than corneal refractive procedures in the included studies, although ICL introduces separate intraocular risks.

PRK for Athletes and Contact Sports

PRK may appeal to patients involved in:

• Boxing
• Martial arts
• Rugby
• Football
• Military activity
• Law enforcement
• Jobs involving facial trauma

There is no permanent LASIK flap that can be displaced.

However, PRK does not protect against:

• Corneal injury
• Retinal injury
• Traumatic cataract
• Orbital injury

Protective eyewear remains important.

PRK After Previous LASIK

Surface ablation may be used to treat selected residual refractive errors after LASIK.

Possible advantages include avoiding the risks of lifting an old flap, such as:

• Epithelial ingrowth
• Flap tears
• Flap striae
• Interface inflammation

The surgeon must consider:

• Existing flap thickness
• Residual stromal tissue
• Original treatment
• Corneal shape
• Haze risk
• Interval since LASIK

Mitomycin C may be considered because surface ablation over a previous flap can carry an increased haze risk.

PRK for Superficial Corneal Scarring

Topography-guided PRK or phototherapeutic keratectomy may be considered for selected superficial scars or irregularities.

The goals may include:

• Smoothing the corneal surface
• Reducing irregular astigmatism
• Improving corrected vision
• Treating refractive error

Deeper scars may not be suitable.

PRK and Presbyopia

Standard PRK does not stop the natural lens from ageing.

Possible strategies include:

• Both eyes corrected for distance with reading glasses
• Monovision
• Mini-monovision
• Leaving mild myopia intentionally
• Considering a lens-based procedure

A contact-lens trial may help assess monovision tolerance.

Cataract Surgery After PRK

Patients who undergo PRK may still develop cataracts later.

Previous PRK alters corneal curvature and may make intraocular lens calculations more challenging.

Patients should retain:

• Preoperative refraction
• Corneal measurements
• Operative reports
• Laser treatment details

Modern post-refractive formulas improve accuracy, but the cataract result remains less predictable than in an untreated regular cornea.

Glaucoma Assessment After PRK

Eye-pressure readings may be underestimated after PRK because the cornea is thinner and biomechanically altered.

Future glaucoma assessment should also consider:

• Optic-nerve appearance
• OCT nerve-fibre measurements
• Visual fields
• Corneal thickness
• Alternative pressure methods

Retinal Risk After PRK

PRK corrects the cornea but does not shorten a highly myopic eyeball.

The patient may remain at increased risk of:

• Retinal tears
• Retinal detachment
• Myopic macular degeneration
• Macular schisis
• Glaucoma

Urgent assessment is required for:

• New flashes
• A sudden increase in floaters
• A curtain or shadow
• Sudden visual loss

Common Myths

“PRK Is an Old and Obsolete Procedure”

False.

PRK remains an important modern refractive procedure, particularly when avoiding a flap is desirable.

“PRK Is Always Safer Than LASIK”

False.

PRK avoids flap complications and may preserve more residual stromal tissue, but it has separate risks such as pain, delayed healing and haze.

“Thin Corneas Should Automatically Have PRK”

False.

A thin cornea may still be structurally unsuitable for any tissue-removing laser procedure.

“PRK Cannot Cause Ectasia”

False.

Ectasia is less commonly reported after PRK than after LASIK but can still occur.

“PRK Has No Dry-Eye Risk”

False.

Corneal nerves and the ocular surface are disrupted during treatment.

“TransPRK Has No Contact with the Eye”

Misleading.

The epithelium may be removed by laser, but the eye still requires examination, medication and bandage contact-lens placement.

“Mitomycin C Makes Haze Impossible”

False.

It reduces haze risk but does not eliminate it.

“Vision Is Clear as Soon as the Epithelium Closes”

False.

The epithelial surface and stroma continue healing after the defect has closed.

“PRK Prevents Presbyopia”

False.

The natural lens continues ageing.

“Correcting High Myopia Removes Retinal Risk”

False.

The eye remains anatomically myopic.

Frequently Asked Questions

Is PRK Better Than LASIK?

Neither is universally better.

PRK may be preferable when:

• Avoiding a flap is important
• The cornea is relatively thin
• Contact trauma is likely
• Surface treatment is otherwise advantageous

LASIK may be preferable when:

• Rapid recovery is important
• The cornea is suitable
• Early discomfort must be minimised
• Easier enhancement is desirable

Is PRK Better Than SMILE?

The answer depends on:

• Prescription
• Corneal structure
• Desired recovery
• Available customisation
• Dry-eye risk
• Occupation
• Enhancement planning

How Painful Is PRK?

Pain varies greatly.

Some patients experience moderate discomfort, while others find the first two days difficult.

A structured pain-control plan makes the recovery more manageable.

Will I Be Able to See During the First Few Days?

Yes, but vision is usually blurred and fluctuating.

Patients can often move around safely indoors but should not expect clear driving vision.

Can I Treat One Eye at a Time?

Yes.

Staged surgery may be considered when:

• The patient is concerned about bilateral discomfort
• Work or caregiving responsibilities make bilateral recovery difficult
• One eye has different clinical considerations

Most patients choose bilateral treatment to avoid two separate recovery periods.

Does the Epithelium Grow Back Completely?

Yes.

The surface epithelial cells regenerate.

However, the excimer-laser stromal reshaping beneath the epithelium remains.

Will the Bandage Lens Improve My Vision?

It mainly protects the cornea and supports healing.

Vision may remain blurry while the lens is present.

Can the Bandage Lens Fall Out?

Yes, although this is uncommon.

Do not replace it yourself.

Contact the clinic.

Can I Rub My Eyes?

No during early healing.

Long-term vigorous eye rubbing should also be discouraged because it may:

• Irritate the ocular surface
• Worsen allergy
• Stress the cornea
• Contribute to ectatic change in susceptible eyes

When Will the Pain Stop?

Pain commonly improves substantially once the epithelium closes, usually within several days.

Persistent or worsening pain requires review.

When Will My Vision Become 20/20?

Some patients achieve 20/20 within several weeks.

Others require one to three months or longer.

Not every patient will reach 20/20 without spectacles.

Will I Need Steroid Drops for Months?

Possibly.

Surface-ablation steroid regimens are often longer than LASIK regimens because they help control stromal inflammation and haze.

The dose is tapered according to:

• Healing
• Haze risk
• Eye pressure
• Clinical findings

Can Steroid Drops Raise Eye Pressure?

Yes.

Eye pressure should be monitored during prolonged steroid treatment.

Can PRK Be Repeated?

An enhancement may be possible if:

• Refraction is stable
• Corneal thickness is adequate
• Tomography remains normal
• Haze risk is acceptable
• The expected benefit justifies the risk

Does PRK Cause Cataracts?

PRK treats the cornea and does not directly cause an age-related cataract.

Patients may still develop cataracts later.

Can PRK Cause Blindness?

Severe permanent visual loss is very rare.

Potential causes include:

• Infection
• Severe scarring
• Ectasia
• Uncontrolled inflammation
• Other unrelated eye disease

The risk is small but not zero.

Can I Wear Contact Lenses Again?

Yes, if required.

Contact lenses may be used for:

• Residual refractive error
• Irregular astigmatism
• Ectasia
• Special visual tasks

Does PRK Change Eye Colour?

No.

The iris is not treated.

Can PRK Treat Lazy Eye?

No.

PRK corrects refractive error but does not reverse amblyopia developed during childhood.

Can I Have Cataract Surgery Later?

Yes.

The cataract surgeon should use post-refractive intraocular-lens calculation methods.

When to Seek Urgent Eye Care

Seek urgent assessment for:

• Increasing pain
• Increasing redness
• Rapidly worsening vision
• Thick discharge
• A white corneal spot
• Marked light sensitivity
• Bandage-lens loss with significant discomfort
• Symptoms worsening after initial improvement
• Eye trauma
• New flashes or floaters
• A curtain or shadow

Severe pain should not automatically be assumed to be normal postoperative healing.

A PRK Assessment Checklist

Visual Goals to Discuss

• Distance vision
• Near vision
• Computer use
• Night driving
• Sports
• Occupation
• Spectacle independence
• Monovision
• Tolerance of glare and halos

Medical Information to Report

• Diabetes
• Autoimmune disease
• Thyroid disease
• Pregnancy or breastfeeding
• Medication
• Allergies
• Previous abnormal scarring
• Healing problems
• Migraine or chronic pain

Eye History to Report

• Dry eye
• Contact-lens intolerance
• Recurrent corneal erosion
• Eye rubbing
• Keratoconus in the family
• Herpetic eye disease
• Glaucoma
• Retinal tears
• Eye trauma
• Previous LASIK or other eye surgery

Tests That May Be Used

• Unaided and corrected vision
• Manifest refraction
• Cycloplegic refraction
• Corneal topography
• Corneal tomography
• Pachymetry
• Epithelial mapping
• Wavefront aberrometry
• Tear-film assessment
• Pupil measurement
• Eye-pressure measurement
• Dilated retinal examination

Questions to Ask the Surgeon

• Am I genuinely suitable for PRK?
• Is my corneal tomography normal?
• Why is PRK recommended instead of LASIK or SMILE?
• Is my prescription stable?
• How much stromal tissue will remain?
• What optical-zone size will be used?
• Will the treatment be conventional PRK or TransPRK?
• Will mitomycin C be used?
• What is my haze risk?
• What pain-control plan will be used?
• How long will the bandage lens remain?
• When can I realistically return to work?
• What is my risk of dry eye?
• What is my risk of ectasia?
• How would residual prescription be treated?
• What symptoms require urgent review?

The Bottom Line

PRK is a surface laser vision-correction procedure.

During PRK:

• The corneal epithelium is removed.
• An excimer laser reshapes the underlying stroma.
• A bandage contact lens protects the surface.
• The epithelium grows back over several days.

PRK may treat:

• Myopia
• Hyperopia
• Astigmatism
• Presbyopia through monovision in selected patients

Potential advantages include:

• No permanent corneal flap
• No risk of traumatic flap displacement
• Preservation of more residual stromal tissue than equivalent LASIK
• Suitability for selected thinner corneas
• Suitability for some contact-sport or trauma-risk occupations
• Ability to perform customised surface treatments

Possible disadvantages include:

• Pain during the first few days
• Slower visual recovery
• A bandage contact lens
• Longer steroid treatment
• Risk of corneal haze
• Greater early visual fluctuation

Possible complications include:

• Slow epithelial healing
• Infection
• Haze
• Scarring
• Dry eye
• Glare and halos
• Residual refractive error
• Regression
• Corneal ectasia
• Rare loss of corrected vision

PRK, LASIK and SMILE can all provide excellent results in appropriately selected eyes.

PRK may be preferable when avoiding a flap is important.

LASIK may provide faster recovery and less early discomfort.

SMILE may provide flap-free treatment with faster epithelial recovery.

ICL may be more appropriate for high prescriptions or corneas unsuitable for tissue-removing laser surgery.

The most important message is:

PRK should not be chosen merely because the cornea is too thin for LASIK. The cornea must still be structurally healthy, the planned treatment must leave adequate tissue, and the expected benefit must justify the slower recovery and haze risk.

References

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