Disciform keratitis is a form of inflammation affecting the cornea, the transparent front part of the eye. The condition is named for the characteristic disc-shaped area of swelling, or edema, that develops within the cornea’s layers. This swelling is a response of the body’s immune system. It is not a direct result of an active infection but a secondary inflammatory reaction that can lead to changes in vision.
Underlying Causes and Triggers
The most frequent origin of disciform keratitis is the Herpes Simplex Virus (HSV-1), the same virus responsible for cold sores. The condition is an immune-mediated response to viral antigens, which are proteins left behind in the cornea from a previous, often dormant, HSV infection. The virus can remain latent in the nerve roots after an initial infection, which may have been a minor conjunctivitis in childhood.
This latent virus can reactivate, and the presence of its proteins can trigger an inflammatory cascade. Your immune system recognizes these foreign proteins and launches an attack, leading to swelling and cloudiness in the cornea’s middle layer, the stroma. While HSV-1 is the primary cause, other viruses, such as the Varicella-zoster virus (VZV) that causes shingles, are less common causes. Certain environmental or physiological factors, including stress, other illnesses, or prolonged sun exposure, may act as triggers for this immune reaction.
Recognizing the Symptoms
A primary symptom is blurred or hazy vision in the affected eye, which is a direct result of the corneal swelling. Patients often report seeing halos around lights, especially at night, which can interfere with driving. Sensitivity to light, a condition known as photophobia, is also a common complaint, along with excessive tearing.
A notable characteristic of disciform keratitis is that it often involves only mild discomfort and redness, or sometimes no pain at all. This is a distinction from other forms of keratitis caused by active infections, which are marked by moderate to intense pain. The lack of pain can sometimes delay a person from seeking medical attention.
Diagnosis and Medical Evaluation
Confirming a diagnosis of disciform keratitis requires an examination by an ophthalmologist. The primary diagnostic tool is the slit-lamp examination, a high-magnification microscope that allows the doctor to view the eye’s structures in detail. During the exam, the ophthalmologist looks for a disc-shaped area of edema and haze within the corneal stroma.
A patient’s medical history is also a component of the diagnostic process. The doctor will likely ask about any previous history of herpetic infections, such as cold sores or a past episode of shingles, to support the clinical findings.
Treatment Approaches
The main goal of treating disciform keratitis is to control the inflammation and reduce corneal swelling to restore vision. The standard treatment involves topical corticosteroids, administered as eye drops. These steroid medications work by suppressing the body’s immune response in the eye, decreasing the inflammation causing the corneal edema. The treatment regimen is tailored to the individual based on the severity of the inflammation.
A second medication often prescribed is an oral antiviral drug, such as acyclovir. The antiviral is not used to treat the current inflammation but serves a prophylactic purpose. It prevents the herpes virus from reactivating while the eye’s immune system is suppressed by the steroid treatment. This dual approach manages the inflammation while safeguarding against a recurrent viral outbreak.
Prognosis and Potential Complications
With prompt diagnosis and appropriate management, the prognosis for an episode of disciform keratitis is generally favorable. The inflammation can be controlled, the corneal swelling can resolve, and vision can often return to its previous state. Delays in diagnosis and treatment, however, can lead to complications that may permanently damage vision.
One of the most significant aspects of this condition is its tendency to recur. Each episode of inflammation carries the risk of causing permanent scarring on the cornea. If scarring occurs in the central part of the cornea, it can lead to a long-term reduction in visual acuity.
Other potential complications include the growth of new, abnormal blood vessels into the cornea (neovascularization) as a response to chronic inflammation. The long-term use of steroid eye drops, which is often necessary to manage recurrent episodes, can sometimes lead to an increase in intraocular pressure, potentially causing secondary glaucoma.