Corneal Ulcers: Symptoms, Causes, Treatment and Visual Recovery

Author: Dr Val Phua
Estimated reading time: 12–14 minutes

A Corneal Ulcer Can Threaten Vision Within a Short Time

A corneal ulcer is an open sore or area of tissue breakdown affecting the cornea—the clear window at the front of the eye.

Most corneal ulcers are associated with infection and inflammation of the cornea, known as microbial keratitis. The infection may be caused by bacteria, fungi, viruses or organisms such as Acanthamoeba.

Common symptoms include:

Eye pain
Redness
Sensitivity to light
Blurred or reduced vision
Excessive tearing
Discharge
A gritty or foreign-body sensation
A white or grey spot on the cornea

Corneal ulcers can enlarge, deepen and scar the visual axis. Severe infection may thin the cornea until it perforates, allowing infection to spread deeper into the eye.

A painful red eye with blurred vision or light sensitivity requires prompt ophthalmic assessment—especially in a contact-lens wearer.

What Is the Cornea?

The cornea is the transparent, dome-shaped surface covering the coloured iris and pupil.

It performs two essential roles:

It protects the inside of the eye from injury and microorganisms.
It provides a large proportion of the eye’s focusing power.

The cornea must remain transparent and smoothly curved for clear vision. Infection, inflammation, thinning or scarring may interfere with the passage and focusing of light.

What Is a Corneal Ulcer?

A typical infectious corneal ulcer consists of:

A break in the outer corneal epithelium
An underlying collection of inflammatory cells or microorganisms within the corneal stroma
Surrounding corneal swelling and inflammation

The abnormal area may appear white, grey or yellow when examined with a slit lamp.

The terms corneal ulcer, infectious keratitis and microbial keratitis are often used in overlapping ways. Strictly speaking, keratitis means inflammation of the cornea, while an ulcer implies epithelial loss with underlying stromal involvement.

Not every keratitis has an ulcer, and not every small corneal white spot is necessarily an active infection.

Is a Corneal Ulcer the Same as a Corneal Abrasion?

No.

Corneal Abrasion

A corneal abrasion is a scratch or loss of the surface epithelium.

It may occur after:

A fingernail injury
Paper or plant trauma
Contact-lens removal
Dust or a foreign body
Rubbing the eye

An uncomplicated abrasion does not initially contain an underlying infectious infiltrate.

Corneal Ulcer

A corneal ulcer usually involves:

An epithelial defect
Infection or significant inflammation beneath the surface
A white or grey stromal infiltrate
Greater risk of scarring and corneal thinning

A corneal abrasion can become infected, especially following contact-lens wear or trauma involving contaminated organic material. The American Academy of Ophthalmology recommends antibiotic prophylaxis for corneal abrasions associated with contact lenses or trauma because of the risk of bacterial keratitis.

What Symptoms Can a Corneal Ulcer Cause?

Eye Pain

Pain may range from a persistent gritty sensation to severe aching.

The cornea has a dense supply of sensory nerves, so even a relatively small defect can be very uncomfortable.

However, pain severity does not always reflect ulcer size. Patients with reduced corneal sensation—such as those with diabetes, previous herpes infection or neurotrophic corneal disease—may have a serious ulcer with surprisingly little pain.

Redness

Redness is commonly most pronounced around the edge of the cornea.

A deeply red eye, particularly when associated with pain, light sensitivity or blurred vision, should not be assumed to be ordinary conjunctivitis.

Sensitivity to Light

Photophobia occurs because corneal inflammation stimulates sensitive ocular nerves and may cause associated inflammation within the anterior chamber.

Patients may find it difficult to open the affected eye in bright light.

Blurred or Reduced Vision

Vision may be affected by:

A central corneal infiltrate
Corneal swelling
Irregularity of the surface
Tearing and discharge
Inflammation within the eye
Subsequent corneal scarring

An ulcer near the centre of the cornea is more likely to threaten detailed vision than a small peripheral lesion.

Tearing and Discharge

The eye may water excessively as a protective response.

Bacterial infection may produce mucous or purulent discharge, although the absence of thick discharge does not exclude a serious infection. Bacterial keratitis commonly presents with pain, redness, blurred vision, light sensitivity, tearing and discharge.

A White Spot on the Cornea

Patients or family members may occasionally see a white, grey or yellow spot over the coloured part of the eye.

This may represent:

A corneal infiltrate
An ulcer
Corneal scarring
A retained foreign body
Another corneal opacity

A new white corneal spot associated with redness, pain or reduced vision requires urgent examination.

Eyelid Swelling

Significant irritation may cause the eyelids to become swollen or difficult to open.

Rapidly worsening swelling, fever or inflammation extending into the surrounding face requires urgent medical assessment.

When Is a Corneal Ulcer an Emergency?

Seek urgent or same-day ophthalmic care for:

A painful red eye
Blurred or reduced vision
Marked sensitivity to light
A visible white spot on the cornea
Increasing discharge
Rapidly worsening symptoms
Symptoms following eye trauma
A painful or red eye while wearing contact lenses
Symptoms after sleeping, showering or swimming in contact lenses
Worsening despite antibiotic drops
Recent eye surgery or corneal transplantation

Do not wait for a routine appointment.

Corneal infections can progress despite pain temporarily improving, particularly if steroid-containing drops have reduced the visible inflammation without controlling the underlying organism.

What Should Contact-Lens Wearers Do Immediately?

If a contact-lens wearer develops unusual pain, redness, light sensitivity, discharge or blurred vision:

Remove the contact lens immediately.
Do not reinsert it.
Do not wear a new pair in the other eye if symptoms are present there.
Seek prompt professional examination.
Do not begin leftover steroid or combination antibiotic-steroid drops.
Keep the lens, case and solution if your ophthalmologist asks you to bring them for testing.

CDC guidance advises removing lenses promptly and avoiding further lens wear until an eye doctor confirms that it is safe.

What Causes Corneal Ulcers?

Bacterial Keratitis

Bacterial infection is a common cause of acute corneal ulceration.

Organisms may enter through a break in the surface caused by:

Contact-lens wear
Trauma
Previous surgery
Eyelid disease
An unhealthy ocular surface

Common organisms include Pseudomonas aeruginosa and Staphylococcus aureus, although the likely bacteria vary with the patient, exposure and geographical location.

Pseudomonas infection is particularly associated with contact-lens wear and may progress rapidly.

Fungal Keratitis

Fungal ulcers may follow trauma involving:

Plant material
Soil
Wood
Agricultural debris
Contaminated water

Fungal keratitis is relatively more common in tropical and subtropical regions and may also occur in contact-lens wearers or people with chronic ocular-surface disease. Important organisms include Fusarium, Aspergillus and Candida species.

Fungal infection may progress more slowly than an aggressive bacterial ulcer but can penetrate deeply into the cornea and respond poorly to ordinary antibiotic drops.

Acanthamoeba Keratitis

Acanthamoeba is a microscopic organism found in water and the environment.

Most cases occur in contact-lens wearers, particularly with:

Tap-water exposure
Swimming in contact lenses
Showering in contact lenses
Hot-tub use
Homemade saline
Poor lens disinfection
Minor corneal injury

Acanthamoeba keratitis may cause severe pain that appears disproportionate to the early clinical signs, although some patients do not have prominent pain.

It can resemble bacterial, fungal or herpes keratitis and may be difficult to diagnose. Early recognition improves the chance of successful treatment.

Herpes Simplex Keratitis

Herpes simplex virus can infect the corneal epithelium and produce a branching or dendritic ulcer.

The virus commonly remains dormant within the nervous system and may reactivate later.

Recurrences may involve:

The corneal epithelium
The deeper corneal stroma
The iris and anterior chamber
Corneal nerves

Herpes stromal keratitis may cause progressive corneal scarring and visual loss. Treatment differs from bacterial ulcers and may involve antiviral drops or tablets, with carefully supervised anti-inflammatory treatment in selected forms.

Herpes Zoster Keratitis

Shingles affecting the ophthalmic division of the trigeminal nerve can involve the cornea.

Patients may develop:

A painful forehead or scalp rash
Blisters around one eye
Light sensitivity
Redness
Reduced corneal sensation
Corneal inflammation

Early systemic antiviral treatment is generally important.

Sterile Corneal Infiltrates

Not every corneal infiltrate is infectious.

Sterile inflammatory infiltrates may be associated with:

Contact-lens hypersensitivity
Blepharitis
Staphylococcal lid disease
Autoimmune disease
Peripheral corneal inflammation
Previous surgery

Sterile infiltrates are often smaller, more peripheral and associated with less epithelial loss than severe microbial ulcers. However, these features are not reliable enough for self-diagnosis.

A contact-lens wearer with a painful red eye should be treated as potentially infectious until examined.

Severe Dry Eye and Exposure

Severe ocular-surface disease can lead to epithelial breakdown, sterile ulceration or secondary infection.

Risk factors include:

Sjögren syndrome
Rheumatoid arthritis
Neurotrophic cornea
Incomplete eyelid closure
Facial-nerve weakness
Chemical injury
Severe dry eye
Limbal stem-cell disease

Advanced dry-eye disease can cause corneal thinning, microbial or sterile ulceration and, in severe cases, perforation.

Who Is at Greater Risk?

Important risk factors include:

Contact-lens wear
Sleeping or napping in lenses
Contact-lens exposure to water
Poor lens or case hygiene
Reusing or topping off solution
Eye trauma
Agricultural or plant-related injury
Eyelid abnormalities
Severe dry eye
Previous herpes infection
Reduced corneal sensation
Diabetes
Immunosuppression
Previous corneal surgery or transplantation
Long-term topical steroid use

Contact-lens wear is one of the most important preventable risk factors for microbial keratitis.

Why Is Sleeping in Contact Lenses Dangerous?

Closing the eyelids reduces the oxygen reaching the cornea.

A contact lens further alters oxygen transmission, tear exchange and the interaction between the cornea and microorganisms.

Sleeping or napping in contact lenses increases the risk of contact-lens-related eye infection approximately six- to eightfold, even when the lens has been approved for extended wear.

An “extended-wear” label does not mean that overnight wear is risk-free.

Why Must Contact Lenses Be Kept Away from Water?

Tap water, swimming pools, hot tubs, lakes and seawater are not sterile.

Water exposure may:

Introduce bacteria, fungi or Acanthamoeba
Cause a soft lens to swell or adhere to the eye
wash away disinfecting solution
contaminate the lens case

Contact lenses should not be cleaned or stored using water. They should normally be removed before showering, swimming, bathing or entering a hot tub.

Can Daily Disposable Lenses Cause an Ulcer?

Yes.

Daily disposables avoid the storage-case and solution risks associated with reusable lenses, but infection can still occur through:

Sleeping in the lenses
Wearing them beyond the recommended period
Water exposure
Poor hand hygiene
Reusing a supposedly single-use lens
Sharing lenses
Wearing lenses during redness or illness

Daily disposable lenses may reduce certain hygiene-related risks but cannot eliminate microbial keratitis.

Can Orthokeratology Cause Corneal Infection?

Yes.

Orthokeratology lenses are worn overnight to temporarily reshape the cornea.

Safe wear requires:

Proper patient selection
Meticulous cleaning and disinfection
Avoidance of tap water
Regular professional review
Immediate assessment of pain, redness or reduced vision

Overnight wear and poor hygiene increase the risk of microbial keratitis. CDC includes corneal-reshaping rigid-lens wear among the risk factors for bacterial keratitis.

Can Decorative or Coloured Lenses Cause Ulcers?

Yes.

Decorative lenses are medical devices even when they have no refractive power.

Risk increases when lenses are:

Bought without professional fitting
Shared
Obtained from unauthorised sellers
Poorly cleaned
Too tight or poorly centred
Worn overnight
Exposed to water

Improperly fitted or contaminated decorative lenses can cause abrasion, infection, scarring and permanent visual loss.

How Is a Corneal Ulcer Diagnosed?

Symptom and Exposure History

Your ophthalmologist may ask about:

Contact-lens type and wearing schedule
Overnight wear
Water exposure
Lens-cleaning practices
Eye trauma
Plant or soil exposure
Previous herpes infection
Current eye drops
Steroid use
Eye surgery
Diabetes or immune problems

These details help determine the likely organism and urgency.

Visual-Acuity Testing

Vision is measured in each eye.

Central ulcers, severe corneal swelling and associated inflammation are more likely to reduce vision.

Slit-Lamp Examination

A slit lamp provides a magnified view of the cornea.

The ophthalmologist assesses:

Location and size
Depth
Edge and appearance
Epithelial defect
Corneal thinning
Surrounding swelling
Anterior-chamber inflammation
Hypopyon
Associated contact-lens or eyelid disease

Fluorescein Dye

Fluorescein is an orange dye that glows green-blue under specialised light.

It highlights areas where the corneal epithelium is missing and helps determine the size and shape of the defect.

Corneal Scraping and Culture

A small sample may be taken from the edge and base of the ulcer after the eye has been numbed.

The specimen may be examined using:

Microscopy
Bacterial culture
Fungal culture
Special stains
PCR or other molecular testing

Scraping is particularly important when an ulcer is:

Large
Central
Deep
Atypical
Progressing rapidly
Associated with significant thinning
Unresponsive to initial treatment
Related to surgery or unusual exposure

CDC advises that a small corneal scraping may be sent to a laboratory to identify the cause of bacterial, fungal or Acanthamoeba keratitis.

Confocal Microscopy

In vivo confocal microscopy provides highly magnified images of the living cornea.

It may support the diagnosis of:

Acanthamoeba cysts
Fungal filaments
Corneal nerve abnormalities

Confocal findings should be interpreted together with the clinical examination, culture and molecular tests.

Anterior-Segment OCT

Anterior-segment OCT may help document:

Ulcer depth
Corneal thickness
Areas of thinning
Response to treatment
Risk of perforation

It complements but does not replace examination and microbiological testing.

Is the Lens or Case Tested?

Contact lenses, cases and solution may occasionally be cultured.

However, organisms found in the case may represent contamination rather than the exact cause of the ulcer. Corneal samples generally provide more direct diagnostic information.

Do not delay seeking care while looking for the old lens or case.

How Are Corneal Ulcers Treated?

Treatment depends on:

Probable organism
Ulcer size and location
Depth
Rate of progression
Corneal thinning
Contact-lens and trauma history
Laboratory findings
Response to initial treatment

Intensive Antimicrobial Eye Drops

Infectious ulcers often require very frequent prescription drops.

For significant bacterial keratitis, antibiotic drops may initially be used:

Hourly
More frequently during an initial loading phase
Through the night in severe cases

The schedule is reduced gradually according to clinical improvement.

Small peripheral ulcers may sometimes be treated with a commercially available broad-spectrum fluoroquinolone. Larger, central or severe infections may require concentrated or “fortified” antibiotics prepared by a pharmacy.

Do not reduce the drops simply because pain improves. The epithelial defect and stromal infiltrate must also be monitored.

Antifungal Treatment

Fungal keratitis requires antifungal medication rather than ordinary antibiotic drops.

Treatment may involve:

Topical antifungal drops
Oral medication in selected cases
Prolonged treatment over weeks or months
Surgery if infection progresses despite medication

Fungal keratitis can be difficult to eradicate and may eventually require corneal transplantation.

Acanthamoeba Treatment

Acanthamoeba keratitis commonly requires prolonged treatment with specialised antiseptic drops.

Treatment may continue for many months because Acanthamoeba cysts are highly resistant.

Early diagnosis is important, and treatment often includes agents such as polyhexamethylene biguanide or chlorhexidine, sometimes combined with another anti-amoebic drug.

Antiviral Treatment

Herpes simplex or herpes zoster keratitis may require:

Antiviral eye drops
Oral antiviral tablets
Carefully supervised steroid treatment for selected stromal or inflammatory disease

Steroids must not be used alone in active epithelial herpes infection because they may worsen viral replication and tissue damage.

Cycloplegic Drops

Drops that temporarily relax the iris and focusing muscles may be prescribed to:

Reduce pain
Relieve ciliary spasm
Reduce the risk of adhesions when internal inflammation is present

These drops may blur near vision and enlarge the pupil temporarily.

Pain Relief

Pain management may include:

Oral paracetamol
Anti-inflammatory pain medicine when medically appropriate
Cycloplegic drops
Treatment of the underlying infection

Anaesthetic eye drops used during examination should not be taken home or repeatedly self-administered. Frequent topical anaesthetic use can delay epithelial healing and cause severe corneal toxicity.

Should the Eye Be Patched?

An infected cornea is generally not patched.

Patching may create a warm, closed environment and delay detection of deterioration. AAO guidance specifically advises against early patching of contact-lens-related or trauma-related abrasions because of the risk of secondary bacterial keratitis.

Are Steroid Eye Drops Used?

Sometimes—but only under close ophthalmic supervision.

Steroid drops may reduce inflammation and limit some forms of corneal scarring in selected bacterial ulcers after:

Appropriate antibiotics have been started
The likely organism has been considered
The infection has shown evidence of control
Fungal, Acanthamoeba and active epithelial herpes infection have been excluded or adequately addressed

Steroids can worsen uncontrolled infection, mask progression and increase corneal thinning.

Never start leftover steroid or combination antibiotic-steroid drops for a painful red eye without examination.

How Often Is Follow-Up Needed?

Follow-up frequency depends on ulcer severity.

A severe ulcer may initially require review:

Every day
Occasionally more than once daily
Until the infection clearly stabilises

AAO guidance recommends daily initial follow-up for severe cases such as deep stromal involvement or an infiltrate larger than approximately 2 mm with extensive suppuration.

At each review, the ophthalmologist assesses:

Epithelial-defect size
Infiltrate size and density
Depth
Corneal thinning
Anterior-chamber inflammation
Pain and vision
Culture results
Medication adherence and toxicity

How Do Doctors Know the Treatment Is Working?

Reassuring changes include:

Less pain and light sensitivity
Reduced discharge
Decreasing redness
More defined or less dense infiltrate edges
Smaller epithelial defect
Reduced corneal swelling
Less anterior-chamber inflammation
Stabilisation of thinning

Vision may remain blurred even when the infection is improving because the cornea is still swollen or developing scar tissue.

Why Might an Ulcer Worsen Despite Antibiotics?

Possible reasons include:

The organism is resistant.
The cause is fungal, viral or Acanthamoeba rather than bacterial.
Drops are not being used frequently enough.
The ulcer is too deep for topical treatment alone.
Steroids were started prematurely.
A retained foreign body remains.
The contact lens is still being worn.
The diagnosis is inflammatory rather than infectious.
Medication toxicity is delaying epithelial healing.
The organism has penetrated into deeper corneal tissue.

A worsening ulcer requires repeat examination, reconsideration of the diagnosis and sometimes further cultures or biopsy.

Is Hospital Admission Required?

Most patients can be treated as outpatients if they can reliably use frequent medication and attend close reviews.

Hospital admission may be considered when:

Drops are required around the clock.
The patient cannot administer treatment.
The ulcer is rapidly progressive.
There is severe thinning or impending perforation.
The infection involves the only useful eye.
Social or cognitive factors make outpatient treatment unsafe.
Surgery may be required urgently.

When Is Surgery Needed?

Surgery may be required when medication cannot control the infection or the cornea is becoming dangerously thin.

Possible treatments include:

Tissue Adhesive

A specialised medical glue may seal a small perforation or area of extreme thinning.

A bandage contact lens may be placed over the adhesive.

Amniotic Membrane

Amniotic membrane may support healing and reduce inflammation in selected cases.

It does not replace antimicrobial treatment when active infection remains.

Corneal Debridement

Removing unhealthy or infected surface material may improve penetration of medication in selected fungal or Acanthamoeba infections.

Therapeutic Corneal Transplant

A therapeutic penetrating keratoplasty removes infected or perforated corneal tissue and replaces it with donor tissue.

It may be needed when:

Infection continues spreading despite intensive treatment.
The cornea perforates.
The infection extends deeply.
Structural integrity cannot be maintained.

The immediate purpose may be to save the eye rather than provide perfect vision.

Corneal transplantation carries risks including graft rejection, recurrent infection, glaucoma, bleeding and retinal detachment.

Will a Corneal Ulcer Leave a Scar?

Many ulcers leave some degree of stromal opacity after healing.

The effect on vision depends on:

Scar size
Density
Depth
Location
Corneal shape
Associated thinning
Health of the rest of the eye

A small peripheral scar may cause little difficulty.

A dense central scar may produce:

Persistent blur
Glare
Irregular astigmatism
Ghost images
Contact-lens intolerance

Can Vision Improve After the Infection Has Healed?

Yes.

Vision may continue improving as:

Corneal swelling settles
The epithelium becomes smoother
Inflammation resolves
The scar remodels
The spectacle prescription stabilises

Improvement may continue for several months.

However, severe central scarring, tissue loss or irregular astigmatism may cause permanent visual limitation.

How Is Vision Rehabilitated After Healing?

Options may include:

Updated spectacles
Rigid gas-permeable contact lenses
Scleral lenses
Treatment of residual dry eye
Phototherapeutic keratectomy for selected superficial scars
Corneal transplantation
Cataract or other surgery if another eye condition is contributing

Rigid or scleral lenses may provide clearer vision by creating a smoother optical surface over an irregular scar.

Can the Infection Return?

Yes, depending on the cause.

Recurrence may occur with:

Herpes simplex
Incomplete fungal treatment
Acanthamoeba cyst survival
Continued contact-lens misuse
Persistent eyelid disease
Ongoing ocular-surface breakdown
Immunosuppression

Treatment should not be stopped prematurely simply because the eye feels better.

When Can Contact Lenses Be Worn Again?

Do not resume contact-lens wear until the ophthalmologist confirms that:

The infection has resolved.
The epithelial defect has closed.
Inflammation is controlled.
The cornea is sufficiently stable.
The lens fit and wearing plan are safe.

The previous lenses and case should generally be discarded.

A new pair, new storage case and fresh solution should be used when lens wear resumes.

Some patients may need to change to:

Daily disposable lenses
Reduced wearing time
A different material or fit
Glasses
Specialised rigid or scleral lenses

Preventing Contact-Lens-Related Corneal Ulcers

Never Sleep in Lenses Unless Specifically Directed

Even prescribed extended-wear lenses carry a greater infection risk than daily wear. Sleeping in lenses increases infection risk substantially.

Keep Lenses Away from Water

Remove lenses before:

Showering
Swimming
Bathing
Entering a hot tub

Never use tap water or saliva to rinse lenses.

Use Fresh Solution

For reusable lenses:

Rub and rinse as directed.
Use fresh disinfecting solution every time.
Never top off old solution.
Do not transfer solution into an unlabelled container.

Care for the Storage Case

The NEI recommends rinsing the case with fresh solution, emptying it, drying it with a clean tissue and storing it open and upside down. Cases should generally be replaced at least every three months.

Wash and Dry Your Hands

Hands should be washed thoroughly and dried before handling lenses.

Wet hands can transfer waterborne organisms onto the lens.

Follow the Replacement Schedule

Do not:

Reuse daily disposable lenses
Extend a fortnightly lens to one month
Continue a monthly lens beyond its prescribed period
Share lenses
Purchase unregulated decorative lenses

Stop Wearing Lenses When the Eye Is Unwell

Do not wear lenses when there is:

Redness
Pain
Discharge
Light sensitivity
Blurred vision
Significant respiratory illness affecting hygiene
A damaged or contaminated lens

Attend Regular Contact-Lens Reviews

Routine review helps assess:

Corneal health
Lens fit
Oxygen transmission
Wearing time
Cleaning technique
Early inflammation or infection

The NEI recommends at least annual eye examinations for contact-lens wearers. More frequent review may be needed for young wearers, overnight lenses, dry eye, allergy or previous complications.

Protect the Eyes from Trauma

Wear suitable safety eyewear when:

Gardening
Cutting wood
Performing construction work
Working with machinery
Handling chemicals
Participating in high-risk sport

Plant-related corneal injuries should be examined promptly because of the risk of fungal infection.

Frequently Asked Questions

Is a corneal ulcer the same as conjunctivitis?

No.

Conjunctivitis affects the membrane covering the white of the eye and inner eyelids.

A corneal ulcer affects the transparent cornea and is more likely to cause significant pain, light sensitivity and reduced vision.

Can a corneal ulcer heal on its own?

A very small sterile lesion may resolve after the underlying cause is addressed.

A suspected infectious ulcer should not be left untreated because it may enlarge, scar or perforate.

Is every white spot on the eye an ulcer?

No.

Other causes include old corneal scars, calcium deposits, foreign bodies and non-infectious inflammation.

A new white spot with pain, redness or visual change requires examination.

Can antibiotic eye drops bought over the counter treat it?

Corneal ulcers require prescription treatment selected according to the likely organism and disease severity.

An inappropriate antibiotic may delay correct diagnosis and treatment.

Can I use leftover antibiotic drops?

No.

The drops may be expired, contaminated, inappropriate or too weak for the organism involved.

Can I use steroid drops to reduce the redness?

Not without an ophthalmologist’s direction.

Steroids may worsen bacterial, fungal, Acanthamoeba or herpes infection and mask clinical deterioration.

Can a corneal ulcer spread to the other eye?

Most bacterial and fungal corneal ulcers are not normally spread directly from one person to another. However, poor hygiene, contaminated lens products or viral disease may expose both eyes.

Do not share drops, towels, lenses or lens cases.

How quickly can bacterial keratitis worsen?

Some aggressive infections can progress over hours or days.

Rapidly increasing pain, infiltrate size, corneal thinning or visual loss requires urgent reassessment.

How long does treatment take?

A small bacterial ulcer may improve over several days, although the surface and vision may take longer to recover.

Fungal and Acanthamoeba infections may require treatment for weeks or months.

Why are my drops required every hour?

Frequent dosing creates and maintains a high antimicrobial concentration within the infected corneal tissue during the most active phase of treatment.

Should I wake during the night to use the drops?

Severe ulcers may require around-the-clock treatment initially. Follow the exact schedule provided by your ophthalmologist.

Can I drive during treatment?

Do not drive if:

Vision is blurred
Light sensitivity is significant
The pupil has been dilated
Pain or medication interferes with concentration
The affected or fellow eye does not meet the legal driving standard

Will I need a corneal transplant?

Most bacterial ulcers treated promptly do not require transplantation.

A transplant may be necessary for uncontrolled infection, perforation or a dense central scar that severely limits vision.

Can children develop corneal ulcers?

Yes.

Possible causes include:

Trauma
Contact lenses
Orthokeratology
Herpes infection
Severe allergy and rubbing
Ocular-surface disease

Children may have difficulty describing symptoms, so persistent redness, light avoidance or inability to open an eye requires prompt assessment.

A Practical Emergency Guide

Situation	Recommended action
Mild irritation after prolonged lens wear but no pain or visual change	Remove lenses and monitor closely; seek review if symptoms do not resolve completely
Redness, pain or light sensitivity in a contact-lens wearer	Remove lenses and arrange urgent ophthalmic examination
White corneal spot	Seek urgent same-day assessment
Blurred or reduced vision	Seek prompt ophthalmic care
Plant, soil or contaminated-water injury	Arrange urgent examination
Worsening despite antibiotic drops	Return urgently for reassessment and possible scraping
Increasing pain, thinning or rapidly enlarging ulcer	Emergency specialist management
Sudden fluid leakage, flattened eye or visible perforation	Immediate emergency eye care

The Bottom Line

A corneal ulcer is an area of corneal tissue breakdown, commonly caused by infection.

Warning symptoms include:

Pain
Redness
Light sensitivity
Blurred vision
Discharge
Excessive tearing
A white or grey corneal spot

Common causes include:

Bacterial infection
Fungal infection
Acanthamoeba
Herpes viruses
Severe ocular-surface inflammation

Contact-lens wear is one of the most important risk factors, particularly when lenses are worn overnight or exposed to water.

Diagnosis may require:

Slit-lamp examination
Fluorescein staining
Corneal scraping
Culture or molecular testing
Confocal microscopy in selected cases

Treatment may involve intensive antibiotic, antifungal, anti-amoebic or antiviral medication. Severe infections require close follow-up and may occasionally require corneal surgery.

A painful red eye in a contact-lens wearer is a corneal infection until proven otherwise. Remove the lens, do not use leftover steroid drops and seek prompt ophthalmic assessment.

References

Rhee MK, et al. Bacterial Keratitis Preferred Practice Pattern. Ophthalmology. 2024.
American Academy of Ophthalmology. What Is a Corneal Ulcer? Updated December 2025.
Centers for Disease Control and Prevention. What Causes Bacterial Keratitis? Updated May 2025.
Centers for Disease Control and Prevention. Clinical Overview of Acanthamoeba Keratitis. Updated March 2025.
Centers for Disease Control and Prevention. What Causes Fungal Keratitis? Updated May 2025.
National Eye Institute. Contact Lenses: Benefits, Risks and Safe Care. Updated December 2024.
Cope JR, et al. Corneal Infections Associated With Sleeping in Contact Lenses. CDC Morbidity and Mortality Weekly Report. 2018.
National Eye Institute. Corneal Conditions and Corneal Transplantation. Updated 2025.