Ultraviolet Keratitis

By admin On Nov 10, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Carrie B. Zaslow

Tracy L. Zaslow

Basics

Also known as photokeratitis
Acute syndrome occur after exposure of the eyes to ultraviolet (UV) radiation.
Painful but usually self-limited

Description

Exposure to various forms of UV radiation leads to corneal edema and sloughing, followed by secondary inflammation of the iris.

Risk Factors

UV exposure to unprotected eyes associated with various recreational and occupational activities
Sources of exposure:
- Welder's arc burns
- Snowblindness
- High-voltage-line short circuits
- Other solar exposure
- Sunlamps
- Damaged metal halide lamps
- Aquaria disinfection lamps
- Laboratory or germicidal UV lamps

Genetics

No genetic association

General Prevention

The mode of prevention depends on the type of exposure.

Recreational sun exposure: Well-fitting sunglasses that meet the American National Standards Institute (ANSI) standards with protection against most UV-A and UV-B radiation
Occupational exposure to solar and artificial-solar UV sources: UV-blocking safety goggles in accordance with ANSI
Occupational exposure to metal halide or mercury vapor lamps: Adherence to the Food and Drug Administration (FDA) radiologic health program is recommended.

Etiology

Cornea transmits light in visible spectrum.
Cornea absorbs light UV spectrum.
- 10–20% of light in UV-A spectrum is absorbed.
- Nearly 100% of UV-C light is absorbed.
Damage to the cornea in UV keratitis:
- Results from absorption of light at the transition point between UV-B and UV-C (290 nm)
- Occurs from absorption in the corneal epithelium, the most anterior part of the cornea, which is several layers thick
- Causes surface epithelial cells to die and desquamate
- Damaged cells contain epithelial nociceptor terminal axons that are destroyed, leading to corneal pain secondary to stimulation of the subepithelial nerve plexus.

Commonly Associated Conditions

Facial edema and erythema, resulting from the same UV exposure injury

Diagnosis

Accurate history, including:
- Type of exposure
- Timing and duration of exposure
- Use of protective eyewear
Visual acuity
Complete ocular exam, including:
- Extraocular movements
- Conjunctiva/sclera/corneas with fluorescein
- Anterior chambers (checking for cell and flare)
- Lenses
- Eversion of the lids to check for foreign bodies
- pH exam

History

Exposure without protective eyewear 6–12 hr prior to onset of symptoms
Symptoms (usually bilateral):
- Intense pain
- Photophobia
- Foreign-body sensation
- Mild to moderate decrease in visual acuity
- Increased lacrimation

Physical Exam

Topical anesthetic generally is needed to obtain a good physical exam.
Penlight exam:
- Tearing, injection, chemosis of the bulbar conjunctiva and corneal haziness
- No discharge present in the tarsal conjunctiva; lack of discharge distinguishes photokeratitis from conjunctivitis.
- Pupils are usually relatively miotic and react sluggishly.
Fluorescein exam: Confluent superficial punctuate staining between the lids
Slit-lamp exam:
- Eversion of the eyelids should not reveal a foreign body.
- Corneal edema and anterior chamber reaction (cell and flare) may be seen.

Diagnostic Tests & Interpretation

A thorough eye exam including fluorescein staining and slit-lamp exam generally is sufficient for diagnosis.

Imaging

Orbit radiographs/US/CT scan/MRI for suspected intraocular foreign body

Diagnostic Procedures/Surgery

pH of tear lake: To distinguish from a chemical burn, check pH of tear lake in lower conjunctival fornix; pH should be normal in UV keratitis.

Differential Diagnosis

Foreign body of the cornea or eyelids
Intraocular foreign body
Corneal abrasion
Thermal burns
Toxic epithelial keratopathy (from exposure to chemicals or drugs)
Exposure keratopathy
Nocturnal lagophthalmos
Conjunctivitis
Stevens-Johnson syndrome
Infectious keratitis
Neurotrophic keratopathy
Contact lens–related problems
Trauma
Dry eye syndrome
Dacryocystitis
Canaliculitis
Scleritis

P.621

Treatment

Treatment is supportive.
Severe pain from the syndrome should be treated with oral analgesics.
Although they do have a role in the physical exam, topical anesthetics should not be prescribed.

ED Treatment

Oral analgesics:
- Mild oral narcotics may be necessary.
- Pain control is important to allow patient to sleep, thus creating an anatomic patch.
Cycloplegic drops:
- Will help to relieve photophobia
- Short-acting agents preferable to avoid long-lasting pupil dilation that can be uncomfortable for patient
Antibiotic ointment:
- To provide prophylaxis against superinfection
- Has secondary effect of providing lubrication and increasing comfort
Pressure patch:
- On the worse eye for 24 hr
- May provide some relief
- Has not been proven to aid in expeditious healing

Medication

Antibiotic ointment (prescribed 3–4×/day for 2–3 days):
- Erythromycin
- Bacitracin
- Polymyxin-bacitracin
Cycloplegics:
- Cyclopentolate 1%
- Homatropine 2–5%
- Scopolamine 0.25%

In-Patient Considerations

Initial Stabilization

Topical anesthesia helps to obtain:

More accurate documentation of visual acuity
More thorough eye exam and fluorescein staining
Do not prescribe on outpatient basis: Interferes with healing and worsens keratitis

Admission Criteria

Patients requiring bilateral patching with severely decreased visual acuity and whose social circumstances make it impossible for the patient to take care of his or her own needs

Discharge Criteria

Nearly all patients may be discharged from the ED following treatment with cycloplegics, topical antibiotics, and patching.
Lesions usually heal completely within 24 hr.
Ophthalmologist referral for patients who have other eye disorders or for those who fail to improve significantly after 24 hr

Ongoing Care

Corneal surface regenerates in 24–72 hr.
Surface regeneration leads to symptom resolution.

Follow-Up Recommendations

Reexamination in 24–48 hr
If symptoms improved: Patient can continue with topical antibiotics q.i.d.
If symptoms not improved and superficial punctate staining is still present: Continue treatment with cycloplegics, antibiotics, and possibly pressure patch.
If new symptoms develop or symptoms persist: Refer to an ophthalmologist.

Patient Monitoring

Long-term monitoring is generally unnecessary with the exception of counseling patients on using protective eyewear.

Patient Education

Depending on their daily activities, patients should be referred to the appropriate resource to learn about protective eyewear:

American National Standards Institute (www.ANSI.org)
FDA Radiological Health Program (www.FDA.gov)

Prognosis

Generally, acute, single episodes heal without long-term sequelae.

Complications

Chronic UV exposure can lead to other sequelae:

Cutaneous melanoma
Ocular melanoma
Erythema
Cataract
Nonmelanocytic skin cancer

Additional Reading

Banerjee S, Patwardhan A, Savant VV. Mass photokeratitis following exposure to unprotected ultraviolet light. J Public Health Med. 2003;25:160.

Lerman S. Direct and photosensitized ultraviolet radiation. In: Fraunfelder FT, Roy FH, eds. Current ocular therapy. Sec. 16. 3rd ed. Philadelphia: WB Saunders, 1990:315–320.

Lubeck D, Greene JS. Corneal injuries. Emerg Med Clin North Am. 1988;6:73–94.

Newell FW. Injuries caused by radiant energy. In: Newell FW, ed. Ophthalmology: Principles and concepts. Chap. 8. 7th ed. St. Louis: CV Mosby, 1992:184–185.

Podskochy A. Protective role of corneal epithelium against ultraviolet radiation damage. Acta Ophthalmol Scand. 2004;82:714–717.

Ehlers JP, Shah CP, eds. The Wills eye manual: office and emergency room diagnosis and treatment of eye disease, 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2008.

Turner A, Rabiu M. Patching for corneal abrasion. Cochrane Database Syst Rev. 2006;CD004764.

Verma AS, Dwarika D, Bhola RM, et al. Photokeratitis following the manipulation of aquaria disinfection lamps. Emerg Med J. 2007;24:232.

Codes

ICD9

370.24 Photokeratitis