Keratitis - Infectious Diseases

What is Keratitis?

Keratitis is an inflammation of the cornea, the clear, dome-shaped surface that covers the front of the eye. This condition can be caused by infectious agents such as bacteria, viruses, fungi, and parasites, or by non-infectious factors like injury, prolonged contact lens use, or exposure to ultraviolet light.

What are the Causes of Infectious Keratitis?

Infectious keratitis arises due to various infectious agents:

Bacterial Keratitis: Commonly caused by Staphylococcus aureus or Pseudomonas aeruginosa, especially in contact lens wearers.
Viral Keratitis: Often due to Herpes simplex virus (HSV) which causes dendritic ulcers, or Varicella-zoster virus, known for causing shingles.
Fungal Keratitis: Typically results from Fusarium or Aspergillus species, often following trauma with organic matter.
Parasitic Keratitis: Often caused by Acanthamoeba, a protozoan found in water, soil, and air, frequently affecting contact lens users.

What are the Symptoms of Keratitis?

The symptoms of keratitis can vary based on its cause but generally include:

Eye redness
Pain and discomfort in the eye
Excessive tearing or discharge
Blurred vision
Sensitivity to light (photophobia)
Foreign body sensation

How is Infectious Keratitis Diagnosed?

Diagnosis of infectious keratitis is primarily clinical, supported by laboratory tests. An eye doctor will perform a thorough eye examination using a slit lamp to examine the cornea closely. In suspected infectious cases, corneal scrapings might be taken for microbiological culture and sensitivity testing to identify the causative organism and guide treatment.

What are the Treatment Options?

Treatment depends on the underlying cause:

Bacterial Keratitis: Treated with topical antibiotics. The choice of antibiotic may depend on the results of the culture and sensitivity tests.
Viral Keratitis: Managed with antiviral medications, such as acyclovir for HSV keratitis.
Fungal Keratitis: Requires antifungal medications. Natamycin is often used for superficial infections, while more severe cases may necessitate systemic antifungal therapy.
Parasitic Keratitis: Often treated with antiseptic agents like chlorhexidine or propamidine isethionate, although treatment can be prolonged and challenging.

How Can Infectious Keratitis be Prevented?

Prevention strategies are crucial, especially for those at higher risk:

Maintain good contact lens hygiene, including proper cleaning and storage.
Avoid wearing contact lenses while swimming or in hot tubs.
Use protective eyewear to prevent trauma to the eyes.
Seek timely treatment for any eye injury or infection.
Avoid direct eye contact if diagnosed with HSV or other contagious conditions.

What is the Prognosis of Infectious Keratitis?

The prognosis of infectious keratitis largely depends on the promptness of treatment and the causative organism. Bacterial keratitis often resolves with appropriate antibiotics, but delays can lead to complications such as corneal scarring or perforation. Viral keratitis may recur and require long-term management. Fungal and parasitic keratitis can be more severe and challenging to treat, often requiring prolonged therapy and sometimes surgical intervention.

Conclusion

Keratitis, especially when infectious, is a serious condition that requires prompt medical attention to prevent complications. Understanding the various infectious agents and maintaining preventive measures are key in managing and reducing the incidence of this eye disease.