Complications and Side Effects of PRK Surgery: Corneal Haze, Dry Eye, Regression, and More

Introduction

Photorefractive Keratectomy (PRK) is one of the most established laser vision correction procedures used to treat myopia, hyperopia, and astigmatism. Unlike LASIK, PRK does not involve creating a corneal flap. Instead, the corneal epithelium is gently removed before the excimer laser reshapes the cornea.

Because there is no flap, PRK is often recommended for patients with thin corneas, individuals involved in contact sports, and military personnel. Although PRK has an excellent safety record and high success rate, like any surgical procedure, it carries the possibility of side effects and complications.

Most side effects are temporary and improve as the eye heals, while true complications are less common and usually manageable with timely treatment.

This comprehensive guide explains the most important complications and side effects of PRK surgery, their causes, prevention, and available treatment options.

What Is PRK Surgery?

PRK is a type of laser refractive surgery in which the outer layer of the cornea (epithelium) is removed. An excimer laser then reshapes the corneal tissue so that incoming light focuses correctly on the retina.

The epithelium naturally regenerates over several days, gradually restoring the smooth ocular surface.

Is PRK a Safe Procedure?

PRK is considered one of the safest refractive surgeries available when performed on carefully selected patients by experienced refractive surgeons.

Modern laser technology, advanced surgical planning, and improved postoperative medications have significantly reduced the incidence of complications.

Most patients achieve:

• Excellent visual outcomes
• Long-term refractive stability
• High patient satisfaction
• Low complication rates

However, understanding potential risks allows patients to recognize warning signs and seek appropriate care promptly.

Common Side Effects vs. Complications

Temporary Side Effects

These are expected during the normal healing process:

• Mild pain
• Foreign body sensation
• Light sensitivity
• Blurred vision
• Excess tearing
• Mild dry eye
• Fluctuating vision

Most resolve within days to weeks.

True Complications

These are less common and may require additional treatment:

• Corneal haze
• Persistent dry eye
• Infection
• Delayed epithelial healing
• Corneal scarring
• Regression
• Irregular astigmatism
• Persistent glare

Corneal Haze After PRK

What Is Corneal Haze?

Corneal haze is one of the best-known complications of PRK. It develops when excessive wound healing causes abnormal collagen remodeling beneath the regenerated epithelium, reducing corneal transparency.

Why Does It Occur?

Following laser treatment, keratocytes become activated and produce extracellular matrix proteins. Excessive healing may result in scar-like tissue that scatters light.

Risk Factors

• High myopia corrections
• Large ablation depth
• Excessive ultraviolet (UV) exposure
• Inadequate steroid use
• Delayed epithelial healing
• Younger patients with stronger healing responses

Symptoms

• Blurred vision
• Reduced contrast sensitivity
• Glare
• Halos
• Difficulty driving at night

Diagnosis

Eye specialists diagnose corneal haze using:

• Slit-lamp examination
• Corneal topography
• Corneal tomography
• Visual acuity testing

Prevention

• Intraoperative Mitomycin-C (MMC) in selected patients
• Prescribed corticosteroid eye drops
• UV-protective sunglasses
• Regular follow-up appointments

Treatment

• Topical corticosteroids
• Lubricating eye drops
• Extended observation for mild haze
• Phototherapeutic Keratectomy (PTK) for persistent significant haze
• Additional refractive procedures when appropriate

Dry Eye After PRK

Why Does Dry Eye Occur?

PRK temporarily affects the corneal nerves responsible for stimulating tear production. Reduced corneal sensitivity can decrease tear secretion and destabilize the tear film.

Symptoms

• Burning sensation
• Foreign body sensation
• Redness
• Fluctuating vision
• Excessive tearing (reflex tearing)
• Eye fatigue
• Sensitivity to wind and air conditioning

Who Is at Higher Risk?

• Pre-existing dry eye disease
• Autoimmune disorders
• Long-term contact lens wear
• Older adults
• Postmenopausal women

Diagnosis

Common tests include:

• Tear Break-Up Time (TBUT)
• Schirmer test
• Ocular surface staining
• Tear osmolarity assessment
• Meibomian gland evaluation

Treatment

• Preservative-free artificial tears
• Lubricating ointments at bedtime
• Anti-inflammatory eye drops (when indicated)
• Warm compresses
• Omega-3 fatty acids (if recommended by the treating physician)
• Punctal plugs in selected cases

Most patients improve within several months as corneal nerves regenerate.

Night Glare and Halos

What Are Glare and Halos?

Glare appears as excessive brightness around lights, while halos are circular rings surrounding light sources.

These symptoms are more noticeable:

• At night
• During rainy weather
• While driving
• In dim illumination

Causes

• Healing changes
• Temporary corneal edema
• Large pupil size
• Residual refractive error
• Mild corneal haze

Treatment

• Observation during healing
• Lubricating drops
• Night-driving precautions
• Enhancement procedures if significant residual refractive error remains after stabilization

Regression of Refractive Error

What Is Regression?

Regression occurs when part of the original refractive error gradually returns after initially successful surgery.

The cornea undergoes natural remodeling during healing, and in some patients, this process partially reverses the intended correction.

Risk Factors

• High myopia
• Hyperopia
• Thin corneas
• Younger age
• Excessive wound healing

Symptoms

• Increasing blur
• Reduced distance vision
• Return of spectacle dependence

Management

• Updated glasses or contact lenses
• Observation if stable
• Enhancement surgery after refractive stability is confirmed

Infection Risk

Although uncommon, infection is one of the most serious complications following PRK.

Causes

• Poor postoperative hygiene
• Failure to use antibiotic drops
• Premature removal of the bandage contact lens
• Eye rubbing
• Contaminated water exposure during early healing

Warning Signs

• Severe pain
• Increasing redness
• Yellow or white discharge
• Sudden vision loss
• Dense corneal infiltrates

Diagnosis

• Slit-lamp examination
• Corneal scraping for microbiological testing (if indicated)

Treatment

• Intensive topical antibiotics
• Antifungal or antiviral medications when appropriate
• Close follow-up
• Hospital admission in severe infections

Prompt treatment is essential to minimize the risk of permanent vision loss.

Delayed Epithelial Healing

The corneal epithelium usually heals within 3 to 5 days. In some patients, healing takes longer.

Risk Factors

• Diabetes mellitus
• Dry eye disease
• Smoking
• Nutritional deficiencies
• Large epithelial defects

Symptoms

• Persistent pain
• Blurred vision
• Light sensitivity
• Delayed recovery

Treatment

• Bandage contact lens
• Lubricating drops
• Antibiotics
• Temporary discontinuation of medications that delay healing when appropriate

Corneal Scarring

Persistent inflammation or severe corneal haze may occasionally lead to permanent corneal scarring.

Symptoms include:

• Reduced visual acuity
• Glare
• Irregular astigmatism

Treatment depends on severity and may include medical therapy or surgical intervention such as PTK.

Undercorrection and Overcorrection

Undercorrection

Residual refractive error remains after surgery.

Overcorrection

Too much corneal tissue is removed, creating the opposite refractive error.

Treatment options include:

• Spectacles
• Contact lenses
• Enhancement procedures after refractive stability

Rare PRK Complications

Although uncommon, other complications may include:

• Corneal ectasia (rare in appropriately screened patients)
• Persistent epithelial defects
• Chronic ocular surface inflammation
• Irregular astigmatism
• Reduced contrast sensitivity
• Chronic neuropathic ocular pain (rare)

Risk Factors for PRK Complications

The likelihood of complications increases with:

• High refractive errors
• Thin corneas
• Severe dry eye disease
• Diabetes
• Autoimmune diseases
• Smoking
• Poor compliance with postoperative medications
• Excessive ultraviolet exposure
• Eye rubbing during recovery

How to Prevent PRK Complications

Patients can reduce the risk of complications by following postoperative instructions carefully.

Before Surgery

• Undergo a comprehensive eye examination.
• Treat existing dry eye disease.
• Stop contact lens wear as instructed.
• Discuss all medical conditions and medications with your surgeon.

After Surgery

• Use prescribed antibiotic and steroid eye drops exactly as directed.
• Avoid rubbing your eyes.
• Wear UV-blocking sunglasses outdoors.
• Attend every scheduled follow-up appointment.
• Avoid swimming, hot tubs, and dusty environments until cleared.
• Use preservative-free lubricating drops regularly.

Recovery Timeline

Seek urgent medical attention if you experience:

• Severe eye pain
• Sudden vision loss
• Increasing redness
• Thick discharge
• Persistent worsening blur
• Bright white corneal spot
• Significant light sensitivity that worsens instead of improving

Frequently Asked Questions

Is corneal haze permanent after PRK?

In most cases, corneal haze is mild and gradually improves over several months. Persistent dense haze is uncommon and can often be managed with medications or additional treatment.

How long does dry eye last after PRK?

Dry eye symptoms are usually temporary and improve over several weeks to months as corneal nerves recover, although recovery time varies among individuals.

Can PRK regression be corrected?

Yes. Depending on the stability of the refractive error and corneal health, glasses, contact lenses, or enhancement surgery may be considered.

Is infection common after PRK?

No. Infection is rare when postoperative instructions and prescribed medications are followed carefully, but it requires immediate treatment if it occurs.

Can night glare disappear after PRK?

Yes. Night glare and halos often improve as the cornea heals and vision stabilizes, although some patients may continue to notice mild symptoms, particularly after high refractive corrections.

Conclusion

PRK remains one of the most reliable and effective laser vision correction procedures, offering excellent long-term outcomes for appropriately selected patients. While temporary side effects such as discomfort, blurred vision, dry eye, and light sensitivity are expected during healing, significant complications—including corneal haze, infection, and regression—are relatively uncommon with modern techniques and proper postoperative care.

Careful patient selection, adherence to prescribed medications, protection from ultraviolet exposure, and regular follow-up visits are essential for minimizing complications and achieving the best visual results. Patients who promptly report unusual symptoms and closely follow their surgeon's recommendations can maximize their chances of a smooth recovery and long-lasting visual improvement.