Keratitis

Keratitis is a condition that affects the cornea, the transparent, dome-shaped window that covers the front of the eye. It is characterised by inflammation of the cornea, which can lead to various symptoms such as eye pain, redness, blurred vision, and sensitivity to light. If left untreated, keratitis can cause permanent damage to the cornea and even result in corneal blindness, making it crucial to seek prompt medical attention if you suspect you may have this condition.

What is Keratitis?

Keratitis, also known as corneal inflammation or a corneal ulcer (in severe cases), can be caused by a variety of factors. Infectious keratitis is caused by microorganisms such as bacteria, viruses, fungi, or parasites, while non-infectious keratitis can be triggered by injuries, dry eye syndrome, eyelid disorders, or exposure to ultraviolet light. Common symptoms of keratitis include eye pain, redness, blurred vision, sensitivity to light, and a sensation of something being stuck in the eye. Prompt diagnosis and treatment of keratitis are essential to prevent the condition from worsening and potentially causing permanent vision loss.

Keratitis, a condition characterised by corneal inflammation, can be broadly classified into two main categories: infectious and non-infectious. Let's delve into the details of these different types of keratitis.

Infectious Keratitis

Infectious keratitis is caused by various microorganisms, including bacteria, fungi, viruses, and protozoa. Here are the main types of infectious keratitis:

• Bacterial Keratitis: This type of keratitis is caused by bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Neisseria gonorrhoeae, and Haemophilus influenzae. It often develops in people who use contact lenses improperly, leading to an increased risk of eye infection.
• Fungal Keratitis: This is caused by fungi such as Aspergillus, Candida, Fusarium, and Pythium insidiosum (a fungus-like organism). It is often associated with contact with plant material or the use of contaminated contact lens care solutions.
• Viral Keratitis: This is primarily caused by the herpes simplex virus (HSV), which can progress from conjunctivitis to keratitis. Other viruses like adenovirus types 8, 19, and 37 can also cause this type of corneal inflammation.
• Protozoal Keratitis: This type is caused by Acanthamoeba, a single-celled organism. It is often associated with inadequate hygiene when using contact lenses and exposure to contaminated water.

Prompt diagnosis and appropriate treatment are crucial in managing infectious keratitis to prevent severe complications and permanent vision loss. Treatment options vary depending on the causative organism and may include antibiotics, antifungals, antivirals, or antiparasitic medicines.

Non-infectious Keratitis

Non-infectious keratitis refers to corneal inflammation that is not caused by microorganisms. Several factors can contribute to the development of non-infectious keratitis, including:

• Local Causes: These include trichiasis (inward-turning eyelashes), giant papillae, foreign bodies in the sulcus subtarsalis (the space between the eyelid and the eyeball), and conditions like xerophthalmia (dry eyes).
• Peripheral Ulcerative Keratitis: This type of keratitis is associated with collagen vascular diseases such as rheumatoid arthritis, granulomatosis with polyangiitis, and systemic lupus erythematosus.
• Neurotrophic Keratitis: Neurotrophic keratitis occurs due to damage to the trigeminal nerve, which can be caused by post-herpes zoster ophthalmicus (shingles affecting the eye area), surgery, or tumours affecting the nerve.
• Exposure Keratitis: This type of keratitis is caused by dryness and damage to the cornea due to inadequate tear film or improper eyelid function.
• Filamentary Keratitis: Filamentary keratitis is characterised by strands of epithelial tissue and mucus on the cornea and is often associated with dry eyes or corneal swelling.
• Interstitial Keratitis: This type of keratitis involves inflammation of the middle layers of the cornea and often affects children and adolescents who have had congenital syphilis.
• Marginal Keratitis: Marginal keratitis involves inflammation of the outer edge of the cornea and is often triggered by bacterial staphylococcal infections.

The treatment for non-infectious keratitis depends on the underlying cause. It may involve addressing the local factors, treating the associated systemic conditions, or using medications to manage inflammation and promote healing.

In conclusion, keratitis can manifest in various forms, each with its unique causes and characteristics. Recognising the different types of keratitis is essential for accurate diagnosis and appropriate treatment. If you suspect that you have keratitis or experience any concerning symptoms, such as eye pain, redness, or vision changes, it is crucial to consult an eye care professional promptly to prevent complications and safeguard your vision.

In addition to the general symptoms mentioned above, there are some early signs of keratitis that you should be aware of:

• Sudden onset of severe eye pain
• Increased sensitivity to light
• Redness of the eye
• Swelling of the eyelids
• Mucopurulent discharge in the conjunctival sac
• Decreased visual acuity

If you notice any of these early signs, it is crucial to seek medical attention immediately. Prompt diagnosis and treatment can help prevent the development of corneal ulcers and other serious complications.

The symptoms of keratitis can vary depending on the underlying cause, but some common signs include:

• Excessive tearing
• Eye discharge
• Inability to open the eye
• Pain and irritation in the affected eye
• Redness of the eye
• Sensitivity to light (photophobia)
• Vision changes, such as blurriness or inability to see

Keratitis, an inflammation of the cornea, can be caused by various factors that are classified as infectious or non-infectious. Infectious keratitis is commonly caused by bacteria such as Staphylococcus, Streptococcus, and Pseudomonas, especially in contact lens wearers who do not properly clean and disinfect their lenses or cases. Viral infections like herpes simplex virus, herpes zoster virus, or adenovirus (a common cause of viral conjunctivitis) can also lead to keratitis if the eye is touched after contact with an infected area. While rare, fungal infections may occur due to contamination from plant material or improper contact lens use. Parasitic infections, typically caused by Acanthamoeba found in water and soil, are more common in contact lens wearers who swim or shower while wearing their lenses.

Non-infectious keratitis can result from injuries such as scratches, scrapes, or cuts to the cornea, as well as from wearing contact lenses improperly, dry eye syndrome, eyelid disorders, and exposure to intense ultraviolet (UV) light. Understanding these various causes of corneal inflammation is crucial for preventing and effectively treating keratitis.

Several factors can increase an individual's likelihood of developing keratitis:

• Contact lens wear, especially sleeping in extended-wear lenses, improper disinfection, and wearing lenses while swimming
• Reduced immunity due to conditions like HIV/AIDS or medications that suppress the immune system
• Corneal injury or trauma
• Eyelid disorders that prevent proper eyelid function and lead to corneal dryness
• Exposure to contaminated water, such as in hot tubs or swimming pools
• Vitamin A deficiency, which is rare in developed countries but more common in areas with malnutrition

Identifying and addressing these risk factors can help prevent the onset of keratitis or reduce the severity of symptoms if the condition does occur.

If left untreated or if treatment is delayed, keratitis can lead to serious complications:

• Corneal ulceration, which is an open sore on the cornea that can cause severe pain and vision problems
• Corneal scarring that can permanently impair vision
• Chronic corneal inflammation
• Corneal neovascularisation, where new blood vessels grow into the typically avascular cornea, potentially causing vision loss
• Corneal perforation, a hole in the cornea that can lead to severe infection and permanent vision loss
• Endophthalmitis, a rare but severe infection of the entire eye interior that can cause blindness
• Glaucoma and phthisis bulbi (end-stage shrunken eye) in severe, untreated cases

To prevent keratitis, several key measures can be taken, particularly for contact lens wearers:

• Proper Contact Lens Care: Follow the schedule for wearing the lenses and follow the care regimen prescribed by your eye doctor. Avoid wearing them while swimming, showering, or engaging in activities that expose the eyes to water.
• Cleanliness: Wash your hands thoroughly with soap and water before handling contact lenses or touching your eyes. Ensure your hands are completely dry before handling lenses or eyes.
• Storage and Cleaning: Use a fresh solution to clean and store contact lenses. Keep the storage case clean and germ-free, and replace it every 3 to 6 months. Never store contact lenses in tap water or saliva.
• General Hygiene: Avoid touching your eyes if you have a cold sore, herpes blister, or any other infection. Frequent hand washing can help reduce the risk of viral outbreaks.
• Eye Protection: Wear proper eye protection, such as sunglasses in bright sunlight, safety goggles when working with chemicals or sharp objects, and avoid exposure to UV light without protection.
• Immune System Health: Maintain a healthy immune system, as a weakened immune system can increase the risk of developing keratitis.
• Regular Check-ups: Regularly visit your eye doctor to monitor the health of your eyes and address any symptoms promptly.

By following these preventive measures, you can significantly reduce your risk of developing keratitis, a condition characterised by corneal inflammation.

If you experience keratitis symptoms such as eye pain, redness, blurred vision, or increased sensitivity to light, it is essential to seek prompt medical attention. Diagnosing keratitis involves a thorough eye exam, fluorescein staining, slit-lamp examination, and corneal scraping or swabbing for microbiological culture and PCR, which are considered standard diagnostic methods in suspected infectious keratitis. Emerging tools like AI-based imaging may support diagnosis but are not yet standard of care (Yu et al., 2025).

• Patient History: Your eye doctor will take a detailed history of your symptoms and any general health problems that may be contributing to the eye issue.
• External Examination: An external examination of the eye using a biomicroscope (slit-lamp) will be performed to examine the cornea and other structures of the eye. A stain such as fluorescein dye may be applied to determine the extent of the keratitis.
• Laboratory Analysis: In some cases, tears or corneal cells may be collected and sent to a lab for analysis to determine the pathogen causing the infection, particularly in cases of infectious keratitis (Bari et al., 2025) 

Keratitis, an inflammation of the cornea, can result from bacterial, viral, fungal, or protozoal infections, as well as physical trauma or underlying health conditions. The treatment approach depends on the cause and may involve topical or systemic medications.

1. Antibacterial Medications

Bacterial keratitis is typically treated with fortified antibiotics (e.g., vancomycin and tobramycin) or fluoroquinolones (e.g., ciprofloxacin, ofloxacin) as first-line therapy (Yu et al., 2025). Cephalosporins and clarithromycin are used in specific cases or as adjuncts, not as initial treatment. Common antibiotics include:

• Tobramycin: Tobramycin is a broad-spectrum aminoglycoside antibiotic that is effective against Gram-negative and some Gram-positive bacteria.
• Amikacin: Amikacin is used in cases of resistant bacterial keratitis, especially when caused by atypical mycobacteria.
• Clarithromycin: Clarithromycin is a macrolide antibiotic that may be used for bacterial keratitis caused by atypical pathogens.
• Cephalosporins: Cefazolin fortified drops are commonly used for Gram-positive bacterial infections.
• Combination therapy: Fortified antibiotic drops, such as cefazolin with tobramycin or gentamicin, are often used based on the severity of the infection.

2. Antifungal Medications

Fungal keratitis requires first-line therapy with topical natamycin or voriconazole. Ketoconazole is generally not preferred due to limited corneal penetration.

• Voriconazole: Voriconazole is a potent antifungal agent often used for severe fungal keratitis caused by Aspergillus and Fusarium species.
• Amphotericin B: Amphotericin B is commonly used as a topical antifungal, particularly for yeast infections such as Candida.
• Fusarium & Aspergillus infections: Natamycin is the first-line treatment for fungal keratitis.
• Refractory Candida keratitis: Fluconazole is administered orally or topically when natamycin or miconazole fails.
• Broad-spectrum antifungal: Ketoconazole (oral and topical) may be used in selected cases, though it is not routinely preferred for keratitis.

3. Antiprotozoal Medications

Protozoal Keratitis is challenging to treat due to the cystic form's resilience (Carnt et al., 2025).

• Biguanides: Polyhexamethylene biguanide (PHMB) and chlorhexidine serve as first-line therapy.
• Pentamidine: Pentamidine is an antiseptic agent that may be used in severe cases.
• Fluoroquinolones: These are not primary antiprotozoal agents but may be used as adjuncts in resistant or mixed infections.

4. Antiviral Medications

Viral keratitis, particularly caused by herpes simplex virus (HSV) or varicella-zoster virus (VZV), requires antiviral therapy to manage the infection and prevent recurrence.

• Acyclovir: Acyclovir is commonly used to treat HSV keratitis and herpes zoster ophthalmicus.
• Famciclovir: Famciclovir is an oral antiviral effective against HSV and VZV, reducing viral replication and severity of symptoms.

5. Additional Treatments

• Non-infectious keratitis treatment may include artificial tears, anti-inflammatory eye medication, and the use of a bandage contact lens to protect the cornea (Bari et al., 2025).
• Cycloplegic Drops: Used to reduce pain and photophobia by relaxing the eye muscles.

If you have been diagnosed with keratitis, it is essential to follow your eye doctor's instructions carefully to ensure proper treatment and recovery. The specific treatment for keratitis will depend on the underlying cause of the condition and its severity. For infectious keratitis, treatment may involve the use of antibiotic, antiviral, or antifungal eye drops, and in more severe cases, oral medication may be necessary. 

Noninfectious keratitis treatment may include artificial tears, anti-inflammatory eye medication, and the use of a bandage contact lens to protect the cornea. To prevent the development of keratitis, it is crucial to practice good contact lens hygiene and to seek medical attention immediately if you experience any symptoms of eye infection or corneal inflammation.

If you experience any symptoms of keratitis, such as eye pain, redness, blurred vision, sensitivity to light, excessive tearing, or discharge, it is important to seek medical attention promptly. This is especially crucial if you wear contact lenses, as delaying treatment can lead to severe complications. If you suspect an eye infection or have a sudden vision change, remove your contact lenses (if applicable) and consult an eye care professional immediately. Early diagnosis and treatment of keratitis are key to preventing permanent damage to your cornea and preserving your vision. Prompt evaluation is essential to reduce the risk of complications.

• Keratitis is a serious inflammatory condition of the cornea that can lead to sight-threatening complications if left untreated.
• Immediate medical attention is necessary if symptoms of keratitis appear.
• Proper hygiene and care of contact lenses can significantly reduce the risk of developing infectious keratitis.
• Early detection and prompt treatment of keratitis are essential for preserving vision and preventing long-term complications.