Photokeratitis: Symptoms, Types, Causes and Treatment

Photokeratitis, sometimes referred to as “sunburn of the eye,” is an acute, painful eye condition resulting from exposure to ultraviolet (UV) radiation. Whether you’re hitting the ski slopes, lounging on a beach, or working under intense artificial lights, understanding photokeratitis is critical for protecting your vision. This article provides a comprehensive overview of the symptoms, types, causes, and treatment options for photokeratitis, synthesizing the latest evidence from scientific literature.

Symptoms of Photokeratitis

Photokeratitis often comes on suddenly, typically after a latent period following UV exposure. Recognizing the symptoms early is vital for seeking prompt care and preventing complications. Individuals may experience a range of discomfort, from mild irritation to severe pain impacting daily activities.

Symptom	Description	Onset	Source(s)
Eye Pain	Sharp, burning, or aching eye pain	6–12 hours post	1,3,8
Redness	Noticeable redness (conjunctival injection)	Acute	1,3
Tearing	Excessive tearing or watering of the eyes	Acute	3,8
Photophobia	Sensitivity to light, difficulty opening eyes	Acute	3,9
Blurred Vision	Temporary reduction in visual clarity	Acute	3
Foreign Body Sensation	Feeling like grit in the eye	Acute	1,3
Swelling	Swelling of conjunctiva (chemosis)	Acute	1

Table 1: Key Symptoms

Understanding the Symptom Spectrum

Photokeratitis symptoms typically appear several hours after UV exposure—often when the individual is no longer in the hazardous environment. The hallmark symptoms include:

• Eye Pain: The most prominent and distressing symptom. Patients often describe it as severe, burning, or gritty. The pain is bilateral if both eyes are exposed 3,8.
• Redness and Tearing: The eyes may appear bloodshot, with increased tear production as the body attempts to flush out the irritant 1,3.
• Photophobia: Light sensitivity can be so intense that patients struggle to open their eyes, even in dim settings 3,9.
• Blurred Vision and Foreign Body Sensation: Vision may be temporarily reduced, and patients frequently report feeling as if sand or grit is present in the eyes 1,3.

Symptom Progression and Duration

Symptoms generally begin 6 to 12 hours after exposure and may persist for 24 to 48 hours 3. The onset can be delayed, making it easy to underestimate the risk during exposure. Fortunately, with appropriate treatment, most cases resolve without permanent damage.

Types of Photokeratitis

Photokeratitis can present in several forms, depending on the source and intensity of UV exposure. Understanding the various types is crucial for prevention and management, especially for those working or playing in high-risk environments.

Type	Exposure Source	Distinct Features	Source(s)
Solar	Sunlight (natural UV)	Often affects outdoor enthusiasts (e.g., skiers, swimmers)	2,6,7
Artificial	Man-made UV (lamps, lasers)	Linked to occupational or recreational activities (e.g., welding, UV lamps)	3,4,8
Snow Blindness	UV reflected by snow	Common in high-altitude environments	2,7
Arc Eye	Welding arcs	Occupational risk, intense and focused exposure	2,8

Table 2: Types of Photokeratitis

Solar Photokeratitis

This is the most common type and results from direct exposure to sunlight, especially in environments with high reflectivity, such as beaches, snowfields, or at high altitudes. The risk is elevated during midday when solar UV intensity peaks 2,7.

Artificial Photokeratitis

Artificial sources such as welding arcs, UV lamps (e.g., tanning beds, germicidal lamps), and certain lasers can emit high levels of UV radiation. Outbreaks have been reported after exposure to faulty metal halide bulbs in gyms or during recreational events with UV displays 3,4,8. Both occupational and accidental exposures fall into this category.

Snow Blindness

Snow blindness is a specific subtype of solar photokeratitis, commonly affecting mountaineers, skiers, and those traveling in snowy environments. Snow reflects up to 80% of UV rays, greatly amplifying exposure risk 2,7.

Arc Eye

“Arc eye” refers specifically to photokeratitis caused by exposure to the intense UV radiation from welding arcs. It’s a well-known occupational hazard for welders who do not use adequate eye protection 2,8.

Causes of Photokeratitis

Photokeratitis is fundamentally a phototoxic injury of the cornea, resulting from excessive exposure to UV radiation. The specific causes and risk factors can vary based on geography, activities, and individual behaviors.

Cause	UV Source	Risk Factors/Amplifiers	Source(s)
Solar UV	Sunlight (UV-A, UV-B)	High altitude, snow, sand, water, midday exposure	1,2,6,7
Artificial UV	Welding, UV lamps, lasers	Lack of eye protection, faulty equipment	3,4,8
Environmental	Ground reflection, ozone thinning	Latitude, season, travel, climate	7
Chemical/Phototoxic	Drugs/chemicals + UV	Less common in cornea; more relevant to skin	1

Table 3: Causes of Photokeratitis

Solar and Environmental Factors

• UV-B and UV-A: Both wavelengths contribute, but UV-B (280–315 nm) is particularly damaging due to its higher energy 6,7.
• Reflective Surfaces: Snow, sand, and water can reflect and intensify UV exposure, significantly increasing risk 2,7.
• Geographical Factors: Altitude, latitude, time of day, and atmospheric conditions (e.g., ozone thickness, clouds) directly influence the intensity of UV radiation reaching the earth’s surface 7.

Artificial Sources

• Welding Arcs: Unprotected exposure during welding operations is a leading cause of occupational photokeratitis (“arc eye”) 2,8.
• UV Lamps and Lasers: Broken or improperly shielded UV lamps in gyms, tanning beds, or during medical procedures (e.g., excimer laser surgery) can cause outbreaks or isolated cases 3,4,8.
• Special Events: Recreational use of UV displays at outdoor events has led to documented clusters of photokeratitis among unprotected attendees 3.

Chemical and Phototoxic Agents

While the cornea is less susceptible than skin, certain phototoxic compounds can exacerbate UV-induced damage if present in the tear film or ocular tissues 1. However, this is a less common etiology for photokeratitis compared to direct UV exposure.

Treatment of Photokeratitis

Prompt recognition and management of photokeratitis are essential for relieving symptoms, accelerating healing, and preventing complications. Most cases resolve with supportive care, but emerging therapies are being explored for more severe or persistent cases.

Treatment	Method	Effect/Outcome	Source(s)
Supportive Care	Rest, cool compresses, lubricants	Symptom relief, healing acceleration	3,8
Topical Antibiotics	Eye drops/ointment	Prevents secondary infection	3,13
Corticosteroids	Topical drops	Reduces inflammation (select cases)	3
Oral Analgesics	Pain relief	Comfort improvement	3
Antioxidants	Fucoxanthin, astaxanthin	Reduces oxidative stress, pain	9,10
Stem Cell Therapy	Subconjunctival injection	Tissue repair, reduces neovascularization	13
UV Protection	Sunglasses, hats	Prevention (not post-exposure)	2,7

Table 4: Treatment Modalities

Supportive and Conventional Treatments

• Immediate Actions: Removing oneself from the UV source and resting the eyes in a darkened environment is the first step.
• Lubricating Eye Drops/Ointments: Prescribed to maintain corneal moisture and promote healing 3,8.
• Topical Antibiotics: Used to prevent secondary bacterial infections, especially if epithelial damage is significant 3,13.
• Corticosteroid Drops: For severe inflammation, short-term topical steroids may be used under medical supervision 3.
• Pain Management: Oral analgesics and cold compresses are recommended for pain relief 3,8.

Emerging and Adjunctive Therapies

• Antioxidant Therapies: Compounds like fucoxanthin and astaxanthin show promise in reducing oxidative stress, inflammation, and pain associated with photokeratitis in animal studies 9,10. These agents act by inhibiting inflammatory pathways and promoting cellular recovery.
• Heat Shock Protein Inducers: Substances such as geranylgeranylacetone (GGA) that induce heat shock proteins (HSP70) may protect corneal tissues and reduce cell death post-UV exposure 11.
• Stem Cell Therapy: Xenografting human umbilical mesenchymal stem cells can expedite corneal repair and reduce inflammation and neovascularization in experimental models 13.

Unproven or Ineffective Treatments

• Retinol Palmitate: In a rat model, topical retinol palmitate did not show significant benefits over standard therapy for UV-induced keratitis 12.

Prevention

• The best treatment is prevention. Use properly rated UV-protective eyewear, hats, and avoid direct sunlight during peak hours, especially in high-risk environments 2,7.

Conclusion

Photokeratitis is a preventable but potentially debilitating condition that arises from acute UV exposure to the eyes. Understanding its symptoms, types, causes, and treatment options empowers individuals, travelers, and professionals to protect their ocular health.

Key Takeaways:

• Symptoms include pain, redness, tearing, photophobia, and blurred vision, usually appearing hours after exposure 1,3,8.
• Types vary based on exposure source—solar, artificial, snow blindness, and arc eye being the most common 2,3,4,7,8.
• Causes are linked to sunlight, reflective environments, artificial UV sources, and, less commonly, phototoxic chemicals 1,2,3,4,6,7,8.
• Treatment is mainly supportive, with topical antibiotics, corticosteroids, and new therapies like antioxidants and stem cells under investigation 3,8,9,10,11,13.
• Prevention is crucial: Always wear UV-blocking eyewear and take protective measures in high-risk settings 2,7.

By staying informed and vigilant, the risk of photokeratitis can be minimized, ensuring long-term ocular health and comfort.