Nummular keratitis

Nummular keratitis is a type of corneal inflammation characterized by the presence of multiple, small, round, white or grayish opacities on the cornea. These opacities are typically arranged in a ring or circular pattern, giving the condition its name, as "nummular" is derived from the Latin word for "coin."

Etiology

Nummular keratitis is often associated with viral infections, particularly those caused by the herpes simplex virus (HSV) and the varicella-zoster virus (VZV). It can also occur as a result of adenovirus infections, which are known to cause epidemic keratoconjunctivitis.

Pathophysiology

The condition is believed to result from an immune response to viral antigens present in the cornea. This immune response leads to the formation of subepithelial infiltrates, which are the hallmark of nummular keratitis. These infiltrates are composed of inflammatory cells and can cause significant corneal edema and corneal scarring if left untreated.

Clinical Presentation

Patients with nummular keratitis typically present with symptoms such as:

• Photophobia (sensitivity to light)
• Tearing
• Foreign body sensation
• Blurred vision
• Redness of the eye

On examination, the characteristic nummular opacities can be observed using a slit lamp.

Diagnosis

The diagnosis of nummular keratitis is primarily clinical, based on the characteristic appearance of the corneal opacities and the patient's history. Corneal staining with fluorescein may be used to assess the extent of epithelial involvement. In some cases, polymerase chain reaction (PCR) testing of corneal scrapings may be performed to identify the causative viral agent.

Treatment

The treatment of nummular keratitis typically involves the use of:

• Topical corticosteroids to reduce inflammation
• Antiviral medications such as acyclovir or valacyclovir if a viral etiology is suspected
• Artificial tears to alleviate symptoms of dryness and irritation

Prognosis

With appropriate treatment, the prognosis for nummular keratitis is generally good. However, some patients may experience recurrent episodes, particularly if the underlying viral infection is not adequately controlled. Chronic or severe cases can lead to permanent corneal scarring and vision impairment.

Prevention

Preventive measures include:

• Prompt treatment of viral eye infections
• Avoidance of contact with individuals who have active viral eye infections
• Good hygiene practices to prevent the spread of infectious agents

See also

• Keratitis
• Herpes simplex keratitis
• Varicella-zoster virus
• Adenovirus
• Corneal ulcer