Description, Causes and Risk Factors:
Viruses are obligate intracellular parasites that contain only one type of nucleic acid within he infectious unit and are unable to replicate by binary fission.
Viral keratitis is a common cause for unilateral blindness in both developing and developed countries. The frequency of viral keratitis has become greater because of the role of newer antibiotics in eliminating the bacterial flora. Estimated prevalence is approximately 150 per 100,000 population.
Both DNA and RNA viruses are responsible for viral keratitis, common corneal infections are caused by DNA viruses-herpes group viruses - Type I, Type II, Type III, VZV (Varicella zoster virus), Cytomegalovirus, and Epstein-Barr virus and adenoviruses.
Doctors believe the disease to herpes simplex virus is a common pathogen; zoster virus, second; Vaccinia virus in the vaccine due to accidental infection of the cornea, adenovirus infection. When the body resistance subsided, such as cold or heat, are a predisposing factor in this disease.
Trigger factors for reactivation:
Intra ocular surgery.
Laser treatment on the eye.
Topical steroids, latanoprost, etc.
Fever, systemic illness.
Symptoms may include:
Reduction in vision (when central cornea isaffected).
Your health care professional will ask you about your symptoms, your vision, and your health in general. Your doctor, or an eye specialist, will use an instrument that magnifies the surface of the cornea to look for a tiny ulcer caused by viral infection. This ulcer when due to herpes simplex tends to send out star-like branches, and is best seen after a dye is used to stain the cornea temporarily. Herpes simplex infection of the cornea may be accompanied by infection of the eyelid. In this case, tiny, painful blisters resembling cold sores of the lips may appear on the eyelid.
Your doctor also may:
Test of how well your pupil responds to light.
Examine your eye using a special instrument called a slit lamp.
Gently swab inside the eyelid to get a sample to send to the laboratory for culture.
Test your visual sharpness and clearness (visual acuity).
The common infection is by adenovirus and is usually self-limiting often needing no treatment at all. Herpes simplex virus keratitis can be severe and will need antiviral treatment. This can be recurrent and may need prolonged treatment. Surgery is not indicated unless the cornea is severely scarred. Viral keratitis is curable with proper medication and followup.
Reactivation of viral keratitis can be initiated by any type of laser treatment, antiglaucoma drugs, topical steroid therapy, exposure to UV light, intraocular surgeries etc, so a proper history and thorough examination is mandatory to rule out preexisting viral disease prior to any invasive procedure on the eye.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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