Viral keratitis is an inflammatory lesion of the cornea of the eye caused by a viral infection. Disease is manifested by vesicular rashes, swelling and redness of the eye, corneal syndrome, ulceration and clouding of the cornea, decreased vision, neuralgic pain. In order to diagnose viral keratitis, biomicroscopy, confocal and endothelial microscopy, pachymetry and keratometry, visual acuity testing, corneal sensitivity determination, cultural, PCR, and ELISA studies are performed. Antiviral, immunomodulatory, antibacterial agents, analgesics, NSAIDs, antioxidants, vitamins, physiotherapy are prescribed for the treatment; if necessary, scraping of the affected epithelium or keratoplasty is performed.
Viral keratitis is one of the manifestations of a common viral infection; it more often affects children and young people. The inflammatory process in viral keratitis can be superficial (affecting only the epithelium and the upper layers of the stroma) or deep (capturing the entire stroma). Disease is accompanied by a decrease in corneal transparency and decreased visual acuity, may be complicated by the development of corneal necrosis, abscesses and ulceration.
Inflammation of the cornea of the eye develops more often and is more severe when it is affected by viruses of simple (HSV) and herpes zoster, related to filtering neurodermotropic viruses.
There are several types of viral keratitis of herpetic nature: primary (primary infection) and post-primary (activation of a latent virus). A herpetic infection can be inactive for a long period, its reservoir is the conjunctival epithelium and the trigeminal nerve ganglion.
According to the variants of the clinical course in ophthalmology, viral keratitis is punctate, vesicular, tree-like, metagerpetic, discoid and diffuse keratouveitis.
The cause of viral keratitis is infection with adenovirus, herpes infection, chickenpox viruses, measles, mumps. The lack of timely treatment of adenovirus conjunctivitis may contribute to the development of viral keratitis.
Predisposing factors for the occurrence are increased permeability or violation of the integrity of the cornea of the eye, weakening of general and local immunity, frequent emotional stress, hypothermia of the body.
Herpetic keratitis can be provoked by other acute respiratory infections and influenza, contributing to a decrease in immune protection and activation of the causative agent of latent infection.
Viral keratitis is characterized by a long course of the disease with frequent relapses; the presence of vesicular eruptions, irregular or tree-shaped infiltrates; decreased corneal sensitivity; concomitant trigeminal neuralgia.
Primary herpesvirus keratitis is acute; it occurs with rashes on the lips, mucous membranes, wings of the nose, eyelids. At the same time, photophobia, lacrimation, redness of the eyes, pain, swelling and clouding of the cornea, the development of secondary infection, lymphadenopathy are noted. When the bubbles are opened, erosions and ulcers develop.
Post-primary herpesvirus keratitis is observed in children who have previously had chickenpox, and in adults against the background of weakened immunity. The course of the disease is subacute, the duration is 2-3 weeks. Discharge from the eye is insignificant, serous-mucous, corneal syndrome is weakly expressed. With each subsequent exacerbation of viral keratitis, the duration of the disease increases, a deeper corneal lesion develops and a sharper decrease in vision.
Pinpoint viral keratitis occurs without a pronounced clinic, characterized by pinpoint opacities of the cornea. With vesicular viral keratitis, small, translucent bubbles are observed on the cornea, which burst quite quickly with the formation of ulcers.
With treelike viral keratitis, small infiltrates are observed in the epithelium and anterior layers of the stroma; in place of ulcerated and fused together herpetic vesicles, characteristic gray lines in the form of tree branches running along the surface corneal nerves are noted. Treelike keratitis proceeds sluggishly, but persistently, usually accompanied by the development of a superficial ulcer of 1-1.5 mm in size and neuralgic pain.
Metaherpetic keratitis is characterized by a long course with severe damage to the corneal stroma, pronounced corneal syndrome, the formation of deep inflammatory infiltrates and massive erosions. The cornea swells and acquires a gray-turbid hue; after the sharpness of the process fades, a rough turbidity remains on it, significantly disrupting vision, perforation is possible. Metagerpetic viral keratitis is combined with anterior uveitis (iridocyclitis), retinal edema.
For discoid viral keratitis, the formation of a grayish-white disc-shaped focus in the central zone of the cornea is typical, accompanied by pronounced swelling and inflammation of the cornea, conjunctiva and eyelids, increased intraocular pressure, and a significant decrease in corneal sensitivity. Discoid keratitis can last from several months to a year, its outcome is a deep clouding of the cornea and a sharp decrease in visual acuity.
Neurogenic keratitis occurs when the first branch of the trigeminal nerve is affected and is usually accompanied by herpetic rashes and severe neuralgic pains in the course of its branching, sometimes – scleritis, optic neuritis or paralysis of the eye muscles, the development of secondary glaucoma.
The diagnosis of viral keratitis is based on the study of the symptoms and features of the course of the disease, its connection with the transferred viral infection; external examination data, visometry, laboratory and instrumental studies.
Biomicroscopy of the eye, confocal and endothelial microscopy of the cornea, pachymetry and keratometry, determination of corneal sensitivity helps to assess the condition of the cornea. A fluorescein instillation test is performed to detect erosions and ulcers of the cornea.
Detection and identification of the causative agent is carried out using a culture study, PCR smear from the conjunctiva and cornea. The titer of virus-specific antibodies in blood serum is determined by the ELISA method. Disease is differentiated from other types of keratitis: fungal and bacterial keratitis.
Treatment of viral keratitis is carried out in a complex; therapy is aimed at suppressing viral infection, stimulating local and general immunity, and the regenerative potential of the cornea.
As part of the etiotropic therapy of viral keratitis, installations of antiviral drugs (interferon, acyclovir, deoxyribonuclease) and interferon inducers, the laying of tebrofen, bonafluorine and oxaline ointments are prescribed. In severe viral keratitis, oral administration of large doses of antiviral agents (acyclovir) is also indicated. Levamizole, extracts of the thymus gland, intramuscular injections of nonspecific gamma globulin are used to correct the immune status.
In order to prevent secondary infection with viral keratitis, antiseptic solutions (sulfacetamide), antibacterial ointments (tetracycline or erythromycin) can be prescribed locally.
In the course of treatment of viral keratitis, painkillers (novocaine, analgin), antihistamines (chloropyramine, diphenhydramine), NSAIDs (phenylbutazone, indomethacin), proteolysis enzyme inhibitors (aprotinin), mydriatics (atropine, cyclopentolate), antioxidants (vitamin E, methylethylpyridinol), vitamins (A, C, PP, group B).
For herpetic ulcers, cryoapplication, laser coagulation is performed; to improve blood supply and corneal trophism, diathermy, diadynamic currents, medicinal electrophoresis, stimulation of regeneration with a helium-neon laser. Corticosteroids in viral keratitis can be used only in very small doses in the form of drops with complete epithelialization of the cornea in the regressive period of the disease.
In the absence of results of drug treatment of viral keratitis and progression of corneal ulceration, surgical intervention is indicated: in superficial forms – scraping of the affected epithelium, in deep forms – layered or through keratoplasty with subsequent rehabilitation and anti-relapse therapy.
With frequent exacerbations of viral keratitis (ophthalmic herpes), vaccination with an antiherpetic vaccine is necessary.
Prognosis and prevention
Deep viral keratitis, occurring with corneal ulceration, leads to persistent intense opacification of the cornea of the eye, sharply reducing visual acuity.
Prevention requires the prevention of primary infection and relapses of infectious diseases with the help of vaccination, “signal therapy”. It is necessary to beware of microtrauma of the cornea, stressful situations, hypothermia and other factors contributing to the exacerbation of the “dormant” infection.