Herpes Keratitis

Herpes keratitis can be defined as the inflammation of the cornea, caused by the infection with the herpes simplex virus. At the moment, this medical condition is considered one of the top causes that leads to corneal blindness. In order to guarantee a favorable prognosis for this condition, a pretty aggressive treatment is required. This condition is more often encountered in men than in women, appearing most commonly as a secondary infection. Children can suffer from herpes keratitis as well, this condition having a high recurrence rate in their case.

Symptoms of Herpes Keratitis

These are some of the most common symptoms associated with herpes keratitis:

• Pain at the level of the affected eye
• Increased sensitivity to light (photophobia)
• Impaired vision (the vision can become blurry)
• Tearing
• Increased blood flow to the affected area (characteristic red appearance – conjunctivitis)
• Vesicle formation at the level of the eyelids
• Inflammation of the lymph nodes in the area.

Classification

Herpes keratitis can be classified into four different categories, in accordance to the anatomical location of the infection:

Infectious epithelial keratitis

• Corneal vesicles
• Small vesicles filled with clear liquid (first sign of infection)
• Dendritic pattern (progression of condition)
• Central epithelial defect
• Dendritic ulcer
• Pathognomonic sign of herpes keratitis
• Specific pattern
• Live virus on the border
• Central ulceration present
• Geographic ulcer
• Enlargement of the dendritic ulcer
• Inflammation of the epithelial cells
• The borders of the ulcer are scalloped
• Marginal ulcer
• Leukocyte infiltration of anterior stroma
• The dendritic ulcer overlaps the anterior stroma (and the subsequent infiltration)
• Can be confused with a marginal ulcer caused by bacterial infection (with staphylococcus)

Neurotrophic keratopathy

• Irregular corneal surface
• Punctate epithelial erosions
• Progression → persistent epithelial defect
• The stroma can also become ulcerated
• The ulceration has an oval form and the borders are smooth
• Often found in the central part of the cornea
• The cornea presents a reduced sensitivity in the respective area
• The cornea can suffer from scarring, necrosis and even perforation

Stromal keratitis

• Inflammation of the corneal stroma – main characteristic
• Necrotizing stromal keratitis
• Infiltrate present at the level of the stroma
• Can progress to ulceration and necrosis
• In severe cases, the cornea can become perforated
• Immune stromal keratitis
• Seen in patients who suffer from recurrent herpetic infections
• Infiltration is also present (may be focal or diffuse)
• New blood vessels can form at the level of the cornea (process known as neovascularization)

Endotheliitis

• Inflammation of the endothelium
• Keratic precipitates
• Edema also present in the epithelium
• No infiltration at the level of the stroma
• No formation of ghost blood vessels
• Inflammation of the iris (from mild to moderate)
• Pain in the respective eye
• Increased sensitivity to light
• Redness may also be present
• Three types – disciform, diffuse and linear.

Diagnosis of Herpes Keratitis

These are the most common methods used for the diagnosis of herpes keratitis:

• Medical history of the patient
• Previous infection with the herpes simplex virus
• When did the symptoms appear for the first time
• Similar problems in the past
• Physical examination
• Essential for a clinical diagnosis – identification of characteristic corneal lesion
• Laboratory diagnosis
• Corneal scraping
• Viral culture
• Viral antigens identification.

The differential diagnosis can be made with the following conditions or situations: rejection of corneal graft, infection with herpes zoster, syphilis (ocular manifestation), impetigo, bacterial infection (with staphylococcus), chlamydia infection, conjunctivitis (viral or allergic), corneal abrasion, corneal ulcer, other types of keratitis (fungal, interstitial), corneal erosion (recurrent) etc.

Herpes Keratitis Treatment

These are the most common measures of treatment recommended for herpes keratitis:

• Epithelial debridement
• Purpose → remove herpes simplex virus → eliminate the risk of stromal keratitis
• Should be performed with caution, so as not to cause further injury in the respective eye
• Recommended – brushing of the epithelial lesions with the help of an applicator (rapid healing, minimal discomfort)
• Antiviral medication
• Oral or topical administration (depending on the severity of the infection)
• Recommended – antiviral ophthalmic gel (ganciclovir), oral antiviral medication (oral acyclovir), cycloplegic agents (adjuvant to the antiviral therapy)
• Topical therapy
• Reduced corneal toxicity
• Requires a smaller number of applications
• Gel formula, easy to apply, with minimal discomfort
• Prolonged usage – epithelial toxicity (common side-effect)
• The patient responds to the treatment in a couple of days, being cured in about two weeks
• Oral therapy
• Advantage – no ocular toxicity
• Same level of efficiency as the topical therapy
• Recommended in patients who suffer from pre-existent conditions, those who have a weak immune system or in children
• May be used in conjunction with the topical therapy
• Recommended – valacyclovir, famciclovir (new medication)
• Keratoplasty
• Recommended in patients who suffer from chronic stromal keratitis
• Often the last line of treatment in those who experience opacity at the level of the cornea or in those who have corneal perforations
• In case of endotheliitis:
• Corticosteroids + antiviral medication
• Topical administration of corticosteroids
• The dosage might be adjusted in accordance to the way the patient responds to the treatment
• In case of neurotrophic keratopathy:
• Non-preserved lubricants
• Eyelid patching
• Bandage contact lenses
• Autologous serum
• Tarsorrhaphy
• Surgical intervention (in patients whose stroma has thinned or in those who present corneal perforation)
• In case of stromal keratitis:
• Topical antiviral medication + cycloplegic agent
• Topical corticosteroids
• Oral antiviral medication
• Associated intraocular pressure – timolol, acetazolamide (systemic administration)
• Cyclosporine – topical administration
• Soft contact lens – when this is placed at the level of the eye, the cornea is prevented from drying
• Tetracycline – recommended in patients who experience cornea melting (can prevent such a thing from further progressing)
• In case of infectious epithelial keratitis:
• Debridement – performed in order to eliminate the infected epithelial tissue
• Antiviral medication + cycloplegic agent
• Corticosteroids – topical administration.

Note: In the situation that the patient suffers from frequent recurrences, the doctor might decide to administer a low-dose of oral antiviral medication, for prophylactic purposes. By taking this medication as recommended, the risk of recurrence is kept down to a minimum.

Herpes Keratitis Pictures

Prognosis

As it was mentioned above, herpes keratitis can affect the cornea to an extreme point, leading to corneal blindness. In such situations, the indication is clearly for a corneal transplant. The more aggressive the treatment will be, the higher the chances for a positive prognosis. In the situation that corneal scarring occurs, the prognosis is not that positive (loss of visual acuity). Apart from the actual scarring, the prognosis can be affected by associated complications, such as glaucoma or uveitis.

Prevention

The main purpose is to prevent recurrent infections with the herpes simplex virus, as this can increase the risk for corneal complications. This is the reason why antiviral medication, such as acyclovir might be administered for prophylactic purposes. Current research is concentrated on creating a vaccine that could be administered for prophylactic purposes. A vaccine would decrease the rate of initial infections with this virus, which would consequently reduce the risk for secondary infections, with ocular manifestations.