Keratitis: Causes, Symptoms, Treatment, and Prevention

Overview

Keratitis is an inflammation of the cornea, the clear, dome-shaped surface that covers the front of the eye. This condition can be painful and, if left untreated, may lead to serious complications, including vision loss. Keratitis can affect people of all ages but is more common in individuals who wear contact lenses, have weakened immune systems, or live in warm climates where eye injuries or infections are more likely.

According to the Centers for Disease Control and Prevention (CDC), keratitis affects approximately 1 million people in the United States each year. Contact lens wearers are particularly at risk, with studies suggesting they are 5 to 10 times more likely to develop keratitis compared to non-wearers (NIH).

Keratitis can be classified into two main types:

• Infectious keratitis: Caused by bacteria, viruses, fungi, or parasites (e.g., Acanthamoeba).
• Non-infectious keratitis: Resulting from injuries, dry eyes, allergies, or underlying conditions like autoimmune diseases.

Symptoms

The symptoms of keratitis can vary depending on the cause and severity but often include:

• Eye redness: The eye may appear bloodshot due to inflammation.
• Eye pain: Ranging from mild discomfort to severe pain, often worsened by blinking or bright lights.
• Excessive tearing or discharge: The eye may water excessively or produce a thick, mucus-like discharge.
• Blurred or decreased vision: Vision may become hazy or cloudy due to corneal inflammation or scarring.
• Sensitivity to light (photophobia): Bright lights may cause significant discomfort.
• Foreign body sensation: A feeling that something is stuck in the eye, even when nothing is present.
• Swelling of the eyelids: The eyelids may become puffy or swollen.
• White spots on the cornea: In some cases, small white patches (infiltrates) may appear on the cornea, visible to an eye doctor.

Symptoms may develop rapidly (within hours) in infectious keratitis or gradually in non-infectious cases. If you experience any of these symptoms, especially if they worsen quickly, seek medical attention promptly.

Causes and Risk Factors

Keratitis can be caused by a variety of factors, including infections, injuries, and underlying health conditions. Below are the primary causes and risk factors:

Infectious Causes

• Bacterial keratitis: Often caused by Staphylococcus aureus, Pseudomonas aeruginosa (common in contact lens wearers), or other bacteria. Poor contact lens hygiene is a major risk factor.
• Viral keratitis: Most commonly caused by the herpes simplex virus (HSV) or varicella-zoster virus (VZV). Herpes keratitis is a leading cause of corneal blindness worldwide (WHO).
• Fungal keratitis: Often linked to eye injuries involving plant material (e.g., tree branches) or contaminated contact lens solutions. Fusarium and Aspergillus are common fungal culprits.
• Parasitic keratitis: Caused by Acanthamoeba, a microscopic organism found in water, soil, and improperly disinfected contact lens cases. This type is rare but severe and difficult to treat.

Non-Infectious Causes

• Eye injuries: Scratches, abrasions, or foreign objects in the eye can lead to inflammation.
• Dry eyes: Chronic dryness can irritate the cornea and increase susceptibility to keratitis.
• Allergies: Severe allergic reactions can cause corneal inflammation.
• Autoimmune diseases: Conditions like rheumatoid arthritis or Sjogren's syndrome may lead to non-infectious keratitis.
• Exposure to UV light: Prolonged exposure to sunlight or artificial UV light (e.g., tanning beds) can cause photokeratitis, a type of corneal sunburn.
• Chemical irritation: Exposure to irritants like smoke, pollutants, or harsh chemicals.

Risk Factors

Certain factors increase the likelihood of developing keratitis:

• Wearing contact lenses, especially extended-wear or improperly cleaned lenses.
• Previous eye injuries or surgeries (e.g., LASIK).
• Weakened immune system (e.g., due to HIV/AIDS, diabetes, or immunosuppressive medications).
• Living in warm, humid climates where fungal and bacterial growth is more common.
• Using corticosteroids or other medications that suppress the immune system.
• Poor nutrition or vitamin A deficiency, which can weaken the cornea's ability to heal.

Diagnosis

If keratitis is suspected, an eye care professional (ophthalmologist or optometrist) will perform a comprehensive eye examination. Diagnostic steps may include:

Medical History and Symptom Review

The doctor will ask about:

• Recent eye injuries or exposure to irritants.
• Contact lens use and hygiene practices.
• History of eye infections or autoimmune diseases.
• Current medications or underlying health conditions.

Eye Examination

• Slit-lamp examination: A microscope with a bright light is used to examine the cornea, eyelids, and other eye structures in detail. This helps identify inflammation, ulcers, or foreign bodies.
• Fluorescein staining: A yellow dye is applied to the eye to highlight corneal abrasions or ulcers under blue light.
• Visual acuity test: Measures how well you can see at various distances.

Laboratory Tests

If an infection is suspected, the doctor may take a small sample of tears or corneal tissue for testing:

• Cultures: To identify bacteria, fungi, or viruses.
• Polymerase chain reaction (PCR): A rapid test to detect viral DNA, such as herpes simplex virus.
• Confocal microscopy: A non-invasive imaging test to detect Acanthamoeba or fungal infections.

In some cases, blood tests may be ordered to check for underlying conditions like autoimmune diseases.

Treatment Options

Treatment for keratitis depends on the underlying cause and severity. Early intervention is critical to prevent complications like corneal scarring or vision loss.

Medications

• Antibacterial eyedrops or ointments: For bacterial keratitis, such as fluoroquinolones (e.g., ciprofloxacin) or aminoglycosides. Severe cases may require oral antibiotics.
• Antiviral medications: For viral keratitis, such as acyclovir (oral or topical) for herpes simplex or ganciclovir for herpes zoster.
• Antifungal eyedrops or oral medications: For fungal keratitis, such as natamycin or amphotericin B. Treatment may last several weeks or months.
• Antiparasitic medications: For Acanthamoeba keratitis, such as polyhexamethylene biguanide (PHMB) or chlorhexidine. These infections are challenging to treat and may require prolonged therapy.
• Steroid eyedrops: Used cautiously to reduce inflammation in non-infectious keratitis or after infection is controlled. Steroids can worsen infections if used too early.
• Artificial tears or lubricating eyedrops: To relieve dryness and discomfort in non-infectious cases.

Procedures and Surgeries

In severe or non-responsive cases, the following procedures may be necessary:

• Corneal debridement: Removal of infected or damaged corneal tissue to promote healing.
• Amniotic membrane transplantation: A biological bandage placed over the cornea to reduce inflammation and support healing.
• Corneal transplant (keratoplasty): For advanced keratitis with significant scarring or perforation, a damaged cornea may be replaced with donor tissue.
• Phototherapeutic keratectomy (PTK): A laser procedure to remove scar tissue and smooth the corneal surface.

Lifestyle and Home Remedies

In addition to medical treatment, the following steps can help manage symptoms and support recovery:

• Avoid wearing contact lenses until the infection or inflammation has completely resolved.
• Wear sunglasses to reduce light sensitivity.
• Apply warm or cold compresses (as recommended by your doctor) to ease discomfort.
• Avoid rubbing the eyes, which can worsen irritation.
• Use a humidifier to add moisture to dry indoor air.
• Follow a balanced diet rich in vitamins A, C, and E to support eye health.

Living with Keratitis

Recovering from keratitis can take time, and managing the condition requires diligence. Here are some tips for daily life:

Managing Discomfort

• Use prescribed medications exactly as directed, even if symptoms improve.
• Protect your eyes from irritants like dust, wind, and smoke by wearing wraparound sunglasses.
• Take over-the-counter pain relievers (e.g., ibuprofen or acetaminophen) as needed for pain, but consult your doctor first.

Follow-Up Care

• Attend all follow-up appointments to monitor healing and adjust treatments as needed.
• If you wear contact lenses, discuss with your doctor when it’s safe to resume use and how to properly disinfect them.
• Report any new or worsening symptoms immediately, such as increased pain, vision changes, or discharge.

Emotional and Mental Health

Chronic or recurrent keratitis can be stressful. Consider the following:

• Join a support group for people with eye conditions to share experiences and coping strategies.
• Practice relaxation techniques like deep breathing or meditation to manage stress.
• Talk to a mental health professional if anxiety or depression arises due to vision changes or chronic pain.

Prevention

Many cases of keratitis can be prevented with proper eye care and hygiene. Here’s how to reduce your risk:

For Contact Lens Wearers

• Wash your hands thoroughly with soap and water before handling contact lenses.
• Use only sterile contact lens solutions recommended by your eye doctor. Avoid tap water or saliva to rinse lenses.
• Replace contact lenses as prescribed (e.g., daily, biweekly, or monthly). Do not extend wear beyond the recommended time.
• Clean and disinfect lenses properly after each use. Rub and rinse lenses as directed, even if using "no-rub" solutions.
• Replace your contact lens case every 3 months and keep it clean and dry between uses.
• Avoid sleeping in contact lenses unless they are specifically designed for extended wear.
• Remove lenses before swimming, showering, or using hot tubs to avoid exposure to waterborne pathogens.

General Eye Care

• Wear protective eyewear (e.g., goggles) during activities that could cause eye injuries, such as sports, gardening, or construction work.
• Avoid touching or rubbing your eyes with unwashed hands.
• Use artificial tears to keep your eyes lubricated if you have dry eyes.
• Protect your eyes from UV exposure by wearing sunglasses with 100% UV protection.
• Manage underlying health conditions, such as diabetes or autoimmune diseases, to reduce the risk of corneal complications.
• Get regular eye exams to detect and treat early signs of eye problems.

For Travelers and Outdoor Enthusiasts

• Avoid exposure to contaminated water, especially in lakes, rivers, or poorly maintained pools.
• Use insect repellent and wear protective eyewear in areas where eye infections are common.
• Carry a small eye care kit with sterile saline solution and artificial tears when traveling.

Complications

If left untreated or improperly managed, keratitis can lead to serious complications, including:

• Corneal ulcers: Open sores on the cornea that can cause severe pain, scarring, and vision loss.
• Corneal scarring: Permanent damage to the cornea that can impair vision. Severe scarring may require a corneal transplant.
• Chronic inflammation: Long-term inflammation can lead to recurrent keratitis or other eye conditions like uveitis.
• Perforation of the cornea: In severe cases, the cornea may develop a hole, leading to infection inside the eye (endophthalmitis) and potential blindness.
• Glaucoma: Increased pressure in the eye due to inflammation or scarring, which can damage the optic nerve.
• Cataracts: Clouding of the eye's lens, which may develop due to chronic inflammation or steroid use.
• Vision loss: Permanent reduction in vision or blindness, particularly if the infection spreads or scarring is extensive.

Early diagnosis and treatment are essential to minimize the risk of these complications. If you suspect keratitis, do not delay seeking medical care.

When to Seek Emergency Care

References and Further Reading

• Mayo Clinic: Keratitis
• CDC: Contact Lens-Related Eye Infections
• National Eye Institute (NEI): Corneal Diseases
• WHO: Blindness and Visual Impairment
• Cleveland Clinic: Keratitis