peripheral ulcerative keratitis (PUK): Definition, Uses, and Clinical Overview

Posted on February 27, 2026 | by dreye

peripheral ulcerative keratitis (PUK) Introduction (What it is)

peripheral ulcerative keratitis (PUK) is an inflammatory condition that causes a corneal ulcer near the edge of the cornea.
It can lead to thinning (“corneal melt”) and, in severe cases, risk of perforation.
PUK is commonly discussed in urgent eye care and in autoimmune or vasculitic systemic disease workups.
Clinicians use the term to describe a specific pattern of peripheral corneal damage that needs prompt evaluation.

Why peripheral ulcerative keratitis (PUK) used (Purpose / benefits)

peripheral ulcerative keratitis (PUK) is not a product or single treatment; it is a diagnosis and clinical pattern. Identifying PUK matters because it can signal a potentially vision-threatening process at the corneal periphery, and it may be associated with systemic inflammatory disease.

In general, the purpose of diagnosing and describing PUK is to:

Protect the cornea’s structural integrity. Peripheral ulceration can progress to thinning and destabilize the cornea.
Reduce inflammation-driven tissue loss. PUK is often driven by inflammatory damage that can outpace healing.
Clarify whether infection is present. Some peripheral corneal ulcers are infectious, while others are “sterile” (immune-mediated). Distinguishing these affects clinical decision-making.
Detect associated eye disease. PUK can occur with nearby inflammation such as conjunctivitis, episcleritis, or scleritis (deeper, more painful inflammation of the white of the eye).
Prompt evaluation for systemic disease when appropriate. In some patients, PUK is linked to autoimmune conditions (for example, systemic vasculitis), making it a marker for broader health assessment.
Guide monitoring intensity and follow-up. The diagnosis helps clinicians communicate severity, risk, and urgency.

Indications (When ophthalmologists or optometrists use it)

Clinicians consider peripheral ulcerative keratitis (PUK) when they see or suspect:

A peripheral corneal epithelial defect (an “open sore”) with adjacent thinning
A crescent-shaped peripheral ulcer near the limbus (the border where cornea meets sclera)
Redness and pain with a peripheral corneal infiltrate (white/gray inflammatory material in the cornea)
Signs of corneal melt or rapidly increasing thinning
Peripheral corneal ulceration occurring with scleritis or severe ocular surface inflammation
Peripheral ulceration in a patient with a history of autoimmune disease or systemic inflammatory symptoms (varies by clinician and case)
A peripheral corneal ulcer in which infection vs immune cause is uncertain and needs structured evaluation

Contraindications / when it’s NOT ideal

Because PUK is a diagnosis rather than a therapy, “contraindications” mainly apply to labeling a case as PUK or pursuing certain approaches before key causes are considered. Situations where another diagnosis or approach may be more appropriate include:

Central corneal ulcers (more centrally located keratitis may fit different categories and risk profiles)
Findings most consistent with primary infectious keratitis without features of peripheral immune-mediated melt (distinction varies by clinician and case)
Non-ulcerative peripheral thinning disorders without an epithelial defect (for example, some degenerations cause thinning but not ulceration)
Trauma-related corneal defects where the peripheral ulcer pattern is not present
Exposure-related or neurotrophic keratopathy patterns where reduced sensation or eyelid closure is the dominant driver (these can still coexist, but the framework differs)
Cases where the appearance is better explained by marginal keratitis associated with eyelid margin disease (blepharitis), rather than true ulcerative melt (terminology varies by clinician and case)

How it works (Mechanism / physiology)

PUK reflects a local tissue-destructive process occurring at the corneal periphery. It is typically described as an ulcer (loss of surface epithelium) with underlying stromal inflammation and thinning.

Relevant anatomy (plain-language explanations included):

Cornea: The clear front window of the eye. It has layers; the epithelium is the surface “skin,” and the stroma is the thick, supportive middle layer.
Peripheral cornea and limbus: The outer edge of the cornea near the limbus, where the cornea meets the sclera (the white of the eye). This region is closer to blood vessels and immune cells than the central cornea.
Tear film and ocular surface: The tear layer and surface tissues influence healing and inflammation.

High-level mechanism (what drives the damage):

In many cases, PUK involves immune-mediated inflammation. Inflammatory cells and signaling molecules can activate enzymes (often described broadly as “proteases”) that break down corneal collagen and extracellular matrix, leading to stromal thinning.
Because the peripheral cornea is near limbal blood vessels and immune activity, it can be more exposed to immune complex deposition and inflammatory recruitment than the central cornea.
PUK can also occur with infection, where pathogens and the immune response together contribute to tissue breakdown. Determining infectious vs noninfectious causes is a core clinical task.

Onset, duration, and reversibility:

PUK can be acute (rapid onset and progression) or more subacute/chronic, depending on the cause and the patient’s inflammatory state.
“Duration” is not fixed and varies by clinician and case, especially when systemic disease activity is involved.
Corneal tissue loss may heal with scarring; lost stromal tissue is not simply restored to original thickness, so early detection and stabilization are emphasized in clinical care discussions.

peripheral ulcerative keratitis (PUK) Procedure overview (How it’s applied)

peripheral ulcerative keratitis (PUK) is not a single procedure. It is a clinical diagnosis that shapes an evaluation and management plan. A typical high-level workflow looks like this:

Evaluation / exam – History: symptom timing, pain level, contact lens wear, trauma, prior eye disease, systemic autoimmune history, and medication history (details vary by clinician and case). – Eye exam: visual acuity, slit-lamp exam of the cornea and limbus, assessment of epithelial defect size, depth of thinning, and any adjacent scleral inflammation. – Staining tests: dyes may be used to highlight epithelial defects. – Intraocular pressure and anterior chamber assessment may be performed depending on findings.
Preparation – If an infectious cause is possible, clinicians may plan diagnostic sampling (commonly called “cultures” or “scrapings”) based on presentation and local practice patterns (varies by clinician and case).
Intervention / testing – Testing may include targeted ocular testing and, when indicated, systemic evaluation to look for associated inflammatory or autoimmune disease (specific labs and referrals vary by clinician and case). – Imaging is sometimes used to document thinning or associated scleral disease, depending on the setting.
Immediate checks – Clinicians reassess for signs of progression, risk of perforation, and whether the clinical picture fits infectious vs immune-mediated disease.
Follow-up – Follow-up frequency depends on severity and progression risk. PUK is often monitored closely when thinning is significant or changing.

Types / variations

PUK is best understood as a pattern that can arise from different underlying causes. Common clinical variations include:

Noninfectious (sterile) inflammatory PUK
Often associated with systemic autoimmune disease or vasculitis (the exact association varies by clinician and case).
May occur with scleritis, which can indicate deeper ocular inflammation.
Infectious peripheral ulcerative keratitis
Caused by pathogens (bacterial, viral, fungal, or parasitic causes are considered depending on risk factors and geography).
Can mimic sterile PUK; infection must be considered because the management priorities differ.
PUK with adjacent scleral involvement
Some patients have concomitant scleral inflammation (episcleritis or scleritis), which may influence urgency and systemic evaluation.
Unilateral vs bilateral
PUK can present in one eye or both. Bilateral involvement can raise suspicion for systemic inflammatory drivers, though this is not definitive.
Severity spectrum
Mild: small peripheral epithelial defect and limited thinning.
Moderate to severe: larger crescentic ulceration, notable stromal melt, or impending/performed perforation risk.
Named clinical entities sometimes discussed in the differential
Certain peripheral ulcer patterns (for example, Mooren ulcer, which is classically described as a painful peripheral ulcerative keratitis without an associated systemic disease) may be discussed as part of the broader PUK landscape. Terminology and classification can vary by clinician and case.

Pros and cons

Pros:

Provides a clear clinical label for a high-risk peripheral corneal ulcer pattern
Helps clinicians communicate urgency and progression risk
Prompts evaluation for infectious vs inflammatory causes, which can look similar
Encourages consideration of systemic disease associations when appropriate
Guides monitoring and documentation of thinning and healing over time
Frames the problem as both a surface ulcer and a structural thinning concern

Cons:

The underlying cause can be complex and multifactorial
Infectious and noninfectious cases can overlap in appearance, complicating early decisions
Can progress quickly in some patients, with risk to corneal integrity
Often requires multidisciplinary coordination (eye care plus systemic evaluation), which can be logistically challenging
Even after control, healing may leave scarring, irregular astigmatism, or reduced vision, depending on location and severity
Recurrence is possible when underlying inflammatory activity is not controlled (varies by clinician and case)

Aftercare & longevity

Aftercare for peripheral ulcerative keratitis (PUK) is less about a single recovery timeline and more about monitoring stability and addressing contributing factors over time. Outcomes and “longevity” of control commonly depend on:

Severity at presentation: deeper thinning or rapid melt can require closer monitoring than superficial ulceration.
Cause (infectious vs immune-mediated): the expected course differs substantially, and mixed pictures can occur (varies by clinician and case).
Ocular surface health: dry eye disease, eyelid margin disease (blepharitis), and exposure issues can affect epithelial healing and comfort.
Systemic disease activity: if PUK is linked to autoimmune disease, long-term stability often depends on broader inflammatory control (specific approaches vary by clinician and case).
Timely follow-up and documentation: repeated exams help confirm whether thinning is stabilizing, healing, or worsening.
Scarring and corneal shape changes: even after the ulcer closes, residual irregularity can affect vision quality and may influence later optical correction needs.

Because PUK can change over days to weeks in active phases, clinicians often emphasize ongoing reassessment rather than a fixed endpoint.

Alternatives / comparisons

Since PUK is a diagnosis, “alternatives” generally mean other diagnoses that can resemble it, or different high-level management pathways once the cause is clarified.

PUK vs observation/monitoring alone

Simple observation is more typical for stable, non-ulcerative peripheral thinning disorders or minor superficial issues.
PUK implies an ulcerative and thinning process where clinicians often consider it higher risk and more time-sensitive (exact decisions vary by clinician and case).

PUK vs infectious keratitis (corneal infection)

Infectious keratitis is driven by pathogens; PUK often emphasizes immune-mediated peripheral melt, but infection can also present peripherally.
The distinction matters because clinicians may prioritize different testing and medication classes based on suspected cause (varies by clinician and case).

PUK vs marginal keratitis

Marginal keratitis is commonly linked to eyelid margin disease and hypersensitivity to bacterial antigens, often with peripheral infiltrates.
PUK more specifically refers to ulceration with stromal thinning/melt at the periphery, which can have broader systemic implications.

Medication-focused vs procedure-focused approaches

Some cases are managed primarily with medical therapies (topical and/or systemic medications depending on cause).
If thinning threatens the structural integrity of the cornea, procedural or surgical options (such as tissue adhesive, protective contact lenses, or grafting) may be discussed in clinical practice. Which path is chosen varies by clinician and case.

peripheral ulcerative keratitis (PUK) Common questions (FAQ)

Q: Is peripheral ulcerative keratitis (PUK) an infection?
PUK can be infectious or noninfectious. Many discussions of PUK focus on immune-mediated inflammation and corneal melt, but infections can mimic or contribute to a similar appearance. Determining the cause is a key part of the clinical evaluation.

Q: Does PUK usually hurt?
Pain can range from mild irritation to severe pain, especially if there is associated scleritis or significant inflammation. Some patients also report tearing, light sensitivity, and a foreign-body sensation. Symptom intensity does not always match the degree of thinning.

Q: Can PUK affect vision permanently?
It can, depending on severity and where scarring or irregularity occurs. Peripheral scarring may have less impact than changes that induce irregular astigmatism or affect the visual axis. Long-term effects vary by clinician and case.

Q: How long does PUK take to heal?
There is no single timeline. Healing depends on the underlying cause (infectious vs inflammatory), the amount of thinning, and how quickly the disease stabilizes. In many cases, clinicians focus on whether the condition is improving on serial exams rather than a fixed number of days or weeks.

Q: Is PUK considered an emergency?
PUK is often treated as urgent because peripheral thinning can progress and threaten corneal integrity in some cases. The level of urgency depends on findings such as the depth of thinning and rate of change. Clinicians determine urgency based on exam details.

Q: What kind of tests might be done for PUK?
Eye-focused evaluation can include slit-lamp examination, staining, and sometimes sampling for laboratory testing if infection is suspected. If an immune-mediated cause is considered, clinicians may coordinate systemic evaluation (blood tests and specialist input) tailored to the patient’s history. The exact testing varies by clinician and case.

Q: What does it cost to evaluate and manage PUK?
Costs vary widely by region, clinic setting, insurance coverage, and the need for lab tests, imaging, medications, procedures, or hospital-based care. Some cases require only office visits and topical therapy, while others require more extensive workup and interventions. A clinic can usually provide a range after evaluation, but it is not uniform.

Q: Can I drive or use screens if I have PUK?
Functional ability depends on pain, light sensitivity, tearing, and whether vision is blurred from the corneal surface problem or medications used during care. Some people can do routine tasks, while others find symptoms too distracting. Safety considerations are individualized and depend on real-time vision and comfort.

Q: Is PUK contagious?
PUK itself is a descriptive diagnosis and is not inherently contagious. However, if the underlying cause is an infectious keratitis, the infection may involve transmissible organisms depending on the pathogen and exposure context. Clinicians evaluate this based on exam findings and risk factors.

Q: Can PUK come back after it improves?
Recurrence can happen, particularly when underlying inflammatory or autoimmune disease remains active or when ocular surface problems persist. Follow-up is used to watch for reactivation and for longer-term corneal changes. Risk varies by clinician and case.