Keratitis

Keratitis refers to the inflammation of the cornea, the clear, dome-shaped outer layer at the front of your eye that covers the pupil and iris. This vital part of the eye plays a crucial role in focusing light onto the retina, enabling clear vision. When the cornea becomes inflamed, it can lead to discomfort, pain, and, if left untreated, serious vision impairment or even blindness. Understanding the nuances of keratitis, from its varied causes to its comprehensive management, is essential for preserving eye health and preventing potential long-term complications.

Keratitis is essentially an inflammatory response affecting the cornea. This inflammation can stem from a variety of sources, broadly categorised into infectious and non-infectious types. The cornea's primary function is to protect the inner eye from foreign particles and to help focus light. When it becomes inflamed, its transparency can be compromised, leading to blurred vision, pain, and increased sensitivity to light. Given its direct impact on vision, keratitis is considered an ocular emergency in many cases, requiring prompt medical attention to prevent permanent damage.

Keratitis is a relatively common eye condition, though its exact prevalence varies depending on the type and geographical location. Microbial keratitis, particularly bacterial keratitis, is a significant cause of vision loss worldwide. The rising use of contact lenses contributes to the overall incidence of infectious keratitis.

Keratitis can be broadly classified into two main categories: infectious and non-infectious. Each category encompasses several specific types:

Infectious Keratitis: Caused by microorganisms invading the cornea.

• Bacterial Keratitis: The most common form of infectious keratitis, often linked to improper contact lens hygiene, eye injuries, or prolonged contact lens wear. Bacteria like Pseudomonas aeruginosa and Staphylococcus aureus are common culprits.
• Viral Keratitis: Caused by viruses, most notably the Herpes Simplex Virus (HSV), which causes cold sores, and the Varicella-Zoster Virus (VZV), which causes chickenpox and shingles.1 HSV keratitis can lead to recurrent episodes and progressive corneal scarring.
• Fungal Keratitis: Less common but often more severe, caused by various fungi, typically following eye injury involving plant material or in individuals with compromised immune systems.
• Acanthamoeba Keratitis: A rare but very serious parasitic infection, predominantly affecting contact lens wearers who expose their lenses to contaminated water (e.g., tap water, hot tubs, swimming pools). It's notorious for its severe pain and resistance to treatment.

Non-infectious Keratitis: Not caused by microorganisms, but rather by injury, environmental factors, or other underlying conditions.

• Traumatic Keratitis: Resulting from a scratch, abrasion, or foreign body in the eye.
• UV Keratitis (Photokeratitis): Also known as "snow blindness" or "welder's flash," caused by excessive exposure to ultraviolet (UV) light, such as from welding arcs, sun lamps, or reflected sunlight off snow or water.
• Exposure Keratitis: Occurs when the cornea is not adequately protected by the eyelids, leading to excessive drying. This can be due to eyelid problems, neurological conditions, or unconsciousness.
• Neurotrophic Keratitis: A degenerative disease caused by damage to the nerves that supply the cornea, leading to reduced corneal sensation and impaired healing.
• Allergic Keratitis: Inflammation due to severe allergic reactions affecting the eye, often part of conditions like vernal keratoconjunctivitis.

The causes of keratitis are varied and depend on whether the condition is infectious or non-infectious.

Causes of Infectious Keratitis:

• Bacteria: Poor contact lens hygiene (e.g., sleeping in lenses, not cleaning them properly, using tap water), contaminated contact lens solutions or cases, eye injuries, or compromised immune systems.
• Viruses: Herpes simplex virus (HSV) is a common cause, often triggered by stress, fever, or excessive sun exposure. Varicella-zoster virus (VZV) can also cause keratitis, particularly in older adults.
• Fungi: Typically enters the eye after an eye injury involving plant material (e.g., a scratch from a branch), or in individuals with weakened immune systems.
• Parasites: Most commonly Acanthamoeba, often associated with contact lenses cleaned with tap water, swimming with lenses, or using homemade saline solutions.

Causes of Non-Infectious Keratitis:

• Eye Injury/Trauma: A scratch, abrasion, or foreign object hitting the eye can damage the corneal surface, leading to inflammation.
• Contact Lens Overuse/Misuse: Wearing contact lenses for too long, sleeping in them, or not cleaning them correctly can deprive the cornea of oxygen and create micro-abrasions, making it vulnerable.
• Exposure to UV Light: Direct exposure to strong UV rays (e.g., from welding, sunbeds, or prolonged sun exposure without proper eye protection).
• Dry Eye Syndrome: Chronic dryness of the eye surface can lead to inflammation and damage to the cornea.
• Eyelid Malfunctions: Conditions where the eyelids don't close properly, leaving the cornea exposed and susceptible to drying and inflammation.
• Weakened Immune System: Conditions or medications that suppress the immune system can make the eye more vulnerable to both infectious and non-infectious keratitis.
• Allergies: Severe allergic reactions can cause inflammation of the cornea alongside conjunctivitis.

The symptoms of keratitis can vary in severity and depend on the underlying cause, but commonly include:

• Eye Pain: Often sharp or gritty, ranging from mild discomfort to severe, debilitating pain.
• Redness: The white part of the eye (sclera) appears red due to inflammation of blood vessels.
• Blurred Vision: The inflammation and swelling of the cornea distort vision.
• Sensitivity to Light (Photophobia): Bright light can be very uncomfortable or even painful.
• Excessive Tearing (Watery Eye): The eye produces more tears as a protective mechanism.
• Discharge: Can be watery, mucous-like, or purulent (pus-like), depending on the cause.
• Feeling of a Foreign Body: A persistent sensation that something is in the eye.
• Difficulty Opening Eyelid: Due to pain, swelling, or irritation.
• Corneal Haze or Opacity: The normally clear cornea may appear cloudy or white.

Accurate and timely diagnosis of keratitis is crucial for effective treatment and preventing vision loss. An ophthalmologist will typically conduct the following:

• Detailed Medical History: Asking about symptoms, contact lens use, recent eye injuries, exposure to chemicals, or any underlying health conditions.
• Visual Acuity Test: To assess the extent of vision loss.
• External Eye Examination: To look for redness, swelling, or discharge.
• Slit-Lamp Examination: Using a specialised microscope (slit-lamp) to thoroughly examine the cornea, iris, pupil, and other structures of the eye under high magnification. Fluorescein eye drops may be used to highlight any damage or ulcers on the corneal surface.
• Corneal Scraping and Culture: If an infection is suspected, a tiny sample of corneal tissue may be gently scraped from the surface of the eye. This sample is then sent to a laboratory to identify the specific microorganism (bacteria, virus, fungus, or parasite) causing the infection and to determine its sensitivity to various antimicrobial drugs. This is particularly important for guiding antibiotic or antifungal treatment.
• Polymerase Chain Reaction (PCR) Testing: For viral infections, PCR can rapidly detect viral DNA or RNA from corneal scrapes.
• Referral to Specialists: In complex cases, or if systemic conditions are suspected, the patient may be referred to other specialists.

Treatment for keratitis largely depends on the underlying cause. Prompt treatment is key to preserving vision.

• Bacterial Keratitis: Typically treated with antibiotic eye drops. For severe infections, drops may be administered frequently (e.g., every 30 minutes, even overnight). Oral antibiotics may be used in conjunction with eye drops in some cases.
• Viral Keratitis: Antiviral eye drops (e.g., ganciclovir, trifluridine) and/or oral antiviral medications (e.g., acyclovir, valacyclovir) are used. In some mild viral cases, only supportive care like artificial tears may be needed.
• Fungal Keratitis: Requires intensive treatment with antifungal eye drops and often oral antifungal medications for an extended period, as fungal infections can be challenging to eradicate.
• Acanthamoeba Keratitis: This is particularly difficult to treat, often requiring a combination of topical amoebicidal medications for several months. Treatment can be prolonged and the prognosis guarded.
• Non-Infectious Keratitis:
  • Traumatic: Artificial tears, lubricating ointments, and sometimes topical antibiotics to prevent secondary infection. An eye patch may be used for comfort.
  • UV Keratitis: Usually resolves on its own within a day or two with rest, cold compresses, and lubricating eye drops. Pain relievers may be necessary.
  • Exposure Keratitis: Lubricating eye drops and ointments, taping eyelids closed at night, or surgical procedures to improve eyelid closure.
  • Neurotrophic Keratitis: Artificial tears, autologous serum eye drops, nerve growth factor eye drops, and in severe cases, tarsorrhaphy (partial eyelid closure) or corneal transplant.
• Pain Management: Pupil-dilating eye drops (cycloplegics) can help reduce pain from ciliary spasms. Oral pain relievers may also be prescribed.
• Corticosteroids: Topical steroid eye drops or oral corticosteroid tablets (Brands available: Wysolone, Omnacortil) may be used to reduce inflammation in some cases, but only after an infectious cause has been ruled out or is being effectively treated, as steroids can worsen certain infections (e.g., viral, fungal).
• Corneal Transplant: In severe cases where extensive corneal scarring or thinning leads to significant vision loss and other treatments fail, a corneal transplant (keratoplasty) may be necessary to restore vision.

While alternative therapies should never replace conventional medical treatment for keratitis, some individuals explore complementary approaches to support eye health and reduce symptoms. Always discuss any alternative therapies with your ophthalmologist, as some can interfere with medications or be harmful.

• Nutritional Support: A diet rich in Omega-3 fatty acids (found in fish oil) and antioxidants (from fruits and vegetables) may support overall eye health.
• Warm/Cool Compresses: Applying a warm compress can help with discomfort and improve blood flow, while a cool compress can reduce swelling and irritation.

• Contact lens wear (especially extended wear, sleeping in lenses, poor hygiene).
• Eye injury or trauma.
• Weakened immune system (due to illness or medication).
• Previous eye surgery or pre-existing eye conditions.
• Exposure to contaminated water (swimming, hot tubs with contact lenses).
• Exposure to harsh UV light without eye protection.
• Dry eye syndrome.
• Lid abnormalities (e.g., conditions that prevent proper eyelid closure).
• History of herpes simplex virus or varicella zoster virus infection.

• Chronic corneal inflammation and scarring, leading to permanent vision loss.
• Corneal ulceration (open sores on the cornea), which can deepen and perforate.
• Perforation of the cornea, a medical emergency requiring urgent surgical repair.
• Secondary infections (e.g., bacterial infection on top of a viral keratitis).
• Glaucoma (increased pressure inside the eye) if inflammation spreads.
• Endophthalmitis (severe infection inside the eye), leading to blindness.
• Need for corneal transplant due to irreversible damage.

• Strictly Follow Treatment: Adhere precisely to your doctor's instructions regarding eye drops and medications, even if symptoms improve.
• Protect Your Eyes: Wear prescribed glasses instead of contact lenses during treatment and recovery, and always use UV-protective eyewear outdoors.
• Maintain Excellent Hygiene: Regularly wash your hands, especially before touching your eyes, and keep any dressings or compresses clean.
• Manage Pain and Discomfort: Use warm or cool compresses, and over-the-counter pain relievers as directed by your doctor.
• Attend All Follow-up Appointments: Regular check-ups are crucial to monitor healing and adjust treatment as needed.

Keratitis is Just a Minor Eye Irritation.

While some forms can be mild, keratitis is a serious condition that can lead to permanent vision loss if not promptly and properly treated.

All Eye Redness Means Keratitis.

Redness is a common symptom of many eye conditions, including less serious ones like conjunctivitis. However, persistent redness accompanied by pain or blurred vision warrants immediate medical evaluation.

You Can Treat Keratitis with Home Remedies.

Many home remedies are ineffective and can even worsen keratitis by introducing new infections or delaying proper medical treatment. Professional medical care is essential.

You should see an eye doctor immediately if you experience any of the following symptoms, especially if they are sudden, severe, or worsening:

• Sudden or severe eye pain.
• Significant eye redness.
• Sudden blurred vision or decrease in vision.
• Extreme sensitivity to light.
• Discharge from the eye.
• A feeling that something is constantly in your eye.
• If you wear contact lenses and experience any of these symptoms.

• What type of keratitis do I have, and what caused it?
• What is the specific treatment plan, and how long will it take?
• Are there any specific side effects I should watch out for with the prescribed medications?
• When can I expect my symptoms to start improving?
• When can I resume wearing contact lenses, if at all?
• What are the long-term risks or potential complications for my vision?
• What steps can I take to prevent this from happening again?

• Lend a hand with daily tasks. Things like reading, driving, or cooking can be tough with blurred vision or discomfort, so offer practical help where you can.
• Help them stick to their treatment. Taking eye drops and medications frequently can be a real challenge, so a gentle reminder can make a big difference.
• Make their environment comfortable. If they're sensitive to light, try dimming the lights, closing the curtains, or suggesting they wear dark glasses.
• Be there emotionally. Dealing with keratitis, especially its impact on vision, can be frightening. Listen to their worries and offer plenty of reassurance.

Keratitis, an inflammation of the cornea, is a critical eye condition that demands prompt attention and appropriate treatment to safeguard vision. Ranging from mild irritation to sight-threatening infections, its diverse causes necessitate accurate diagnosis and tailored therapeutic approaches. While certain types, particularly those linked to contact lens misuse, are largely preventable through rigorous hygiene, others may arise from injuries, environmental factors, or underlying health issues. Understanding the symptoms and knowing when to seek urgent medical care are paramount. With timely intervention and dedicated management, individuals affected by keratitis can often achieve a full recovery and preserve their precious sight.