VIRAL KERATITIS

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• VIRAL KERATITIS

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Introduction

• 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.
• Viruses that cause corneal disease are
• Herpes simplex ( HSV)
• Varicella zoster ( VZV)
• Epstein Barr ( EBV)
• Adenovirus
• Cytomegalovirus (CMV) can also cause keratitis
  and is more commonly associated with AIDS

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Epidemiology and pathogenesis

• HSV, VZV, EBV, and CMV are all members of the
  family Herpesviridae.
• DNA viruses
• There are two types of HSV
• HSV-1 is more commonly associated with labial and
  ocular infection.
• HSV-2 is associated with genital infection.

Ophthalmology 2004, (2), 475-481
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Epidemiology and pathogenesis

• Herpes simplex keratitis is a leading cause of
  corneal blindness in the developing world.
• Estimated prevalence is approx 150 per 100,000
  population.
• Ocular HSV tends to be a unilateral disease with
  only one eye affected by primary disease in
  approx 80-90 of cases.
• Atopy appears to be risk factor for bilateral
  disease, is associated with gastric cancer,
  lumbar zoster, malaria and pulmonary tuberculosis

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HERPES SIMPLEX KERATITIS

• Herpes Simplex Keratitis occurs in two forms
• Primary
• Recurrent

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Primary HSV-1 (HSV type 1) infections

• Occurs most commonly in the mucocutaneous
  distribution of the
• trigeminal nerve.
• spread of
• Primary virus Infected
  Nearby
• Infection epithelial cells sensory nerve
• endings
• Viral genome Cell body in transport
  along
• enters nucleus trigeminal ganglion nerve
  axon
• at neuron
• (Persists indefinitely
• in a latent state)
• www.emedicine.com

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PRIMARY HSV-1

• Primary infection of any of the 3 branches
  (ophthalmic, maxillary, mandibular) of cranial
  nerve V leads to latent infection of nerve cells
  in trigeminal ganglion.
• Interneuronal spread of HSV within ganglion
  allows patients to develop ocular disease without
  ever having had primary ocular HSV infection.
• www.emedicine.com

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RECURRENT HSV INFECTION

• Has been thought of as reactivation of virus in
  the sensory ganglion.
• Virus migrates down nerve axon to produce lytic
  infection in ocular disease.
• Recent evidence suggests, virus may subsist
  latently within corneal tissue, serving as a
  potential source of recurrent disease.
• www.emedicine.com

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CLINICAL FINDINGS

• Primary Herpes Simplex Keratitis
• Infrequently seen
• Manifested as vesicular blepharoconjunctivitis
  occasionally with corneal involvement
• Usually occurs in young children
• Topical antiviral therapy may be used as
  prophylaxis and as therapy
• Vaughan Asburys General Ophthalmology 16th
  Edition, 136

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CLINICAL FINDINGS

• Recurrent type herpetic keratitis
• Attacks triggered by
• Fever
• Overexposure to UV light
• Trauma
• Onset of menstruation
• Local/ systemic source of immunosuppression
• Bilateral lesions develop in 4-6 of patients and
  seen mostly in atopic patients.

Vaughan Asburys General Ophthalmology 16th
Edition, 136
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SYMPTOMS

• Irritation
• Photophobia
• Tearing
• Reduction in vision (when central cornea is
  affected)
• Corneal anesthesia usually occurs early in the
  course of infection and thus symptoms may be
  minimal.

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SYMPTOMS

• Corneal ulceration can occasionally be the only
  sign of recurrent herpetic infections

Recurrent herpes simplex virus dendritic ulcer
with an adjacent stromal scar
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LESIONS Dendritic ulcer

• Most characteristic lesion, occurs in corneal
  epithelium
• Typical branching, linear pattern with feathery
  edges and terminal bulbs at ends.
• Visualized by fluorescein staining

HSV dendritic ulcer stained with fluorescein
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Dendritic keratitis
This patient suffers from herpetic keratitis.
Fluorescein staining reveals  dendritic ulcer
typical of herpes keratitis. This is treated with
topical 3 acyclovir
www.eyecasualty.co.uk/.../ cornealinfections.html

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Geographic ulceration

• Form of chronic dendritic disease.
• Delicate dendritic lesions take a broader form.
• Corneal sensation is diminished

HSV geographic ulcer
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Other corneal lesions

• Other corneal epithelial lesions caused by HSV
  are
• Blotchy epithelial keratitis
• Stellate epithelial keratitis
• Filamentary keratitis
• Usually transitory, often become typical
  dendrites within a day or two.

Filamentary keratitis
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Subepithelial lesions

• Caused by HSV infection
• Ghost like image, larger than original epithelial
  defect seen in the area immediately underlying
  epithelial lesion.
• Does not persist for more than a year

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Disciform keratitis

• Most common form of stromal disease in HSV
  infection.
• Edematous stroma without significant infiltration
  and usually without vascularization.
• Edema is most prominent sign.
• Keratic precipitates may lie directly under
  disciform lesion but may also involve the
  endothelial lesion.

Vaughan Asburys General Ophthalmology 16th
Edition, 136
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Peripheral lesions of the cornea

• Caused by HSV
• Usually linear lesions, show loss of epithelium
• Testing for corneal sensation is unreliable.
• Patient is far less photophobic than patients
  with nonherpetic corneal infiltrates.

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Treatment

• Should be directed at eliminating viral
  replication within the cornea, while minimizing
  damaging effects of inflammatory response.

Vaughan Asburys General Ophthalmology
16th Edition, 136-137
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Treatment

• DEBRIDEMENT
• Epithelial debridement is an effective way to
  treat dendritic keratitis
• Infected epithelium is easy to remove with
  tightly wound cotton tip applicator.
• Adjunctive therapy with topical antiviral
  accelerates epithelial healing.

Vaughan Asburys General Ophthalmology 16th
Edition, 136-137
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Treatment
TREATMENT DRUGS
Ophthalmology 2004, (2), 475-482
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Treatment

• Trifluridine and acyclovir are much more
  effective in stromal disease than others.
• Idoxuridine and trifluridine are frequently
  associated with toxic reactions.
• Oral acyclovir may be useful in treatment of
  severe herpetic eye disease particularly in
  atopic individuals.

Vaughan Asburys General Ophthalmology
16th Edition, 136-137
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Treatment

• Oral acyclovir DOSAGE
• For active treatment 400 mg five times daily in
  nonimmunocompromised patients.
• 800 mg five times daily in compromised and atopic
  patients.
• Prophylactic dosage in recurrent disease is 400
  mg twice daily.
• Famciclovir or valacyclovir may also be used.
• Topical corticosteroids accelerate corneal
  thinning, increasing risk of corneal perforation.

Vaughan Asburys General Ophthalmology 16th
Edition, 136-137
25
Surgical treatment

• Penetrating keratoplasty indicated for visual
  rehabilitation in patients with sever corneal
  scarring. Should not be undertaken until herpetic
  disease has been inactive for many months.
• Systemic antiviral agents should be used for
  several months after keratoplasty to cover use of
  topical steroids.
• Lamellar keratoplasty has advantage over
  penetrating keratoplasty of reduced potential for
  corneal graft rejection.

Vaughan Asburys General Ophthalmology 16th
Edition, 136-137
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Varicella zoster viral keratitis (VZV)

• Occurs in two forms
• Primary ( varicella)
• Recurrent ( herpes zoster)
• Ocular manifestations are uncommon in varicella
  but common in ophthalmic zoster.

Vaughan Asburys General Ophthalmology 16th
Edition, 136-137
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Varicella zoster viral keratitis (VZV)

• Ocular manifestations
• Usual eye lesions are pocks on lids and lid
  margins.
• Keratitis occurs rarely.
• Epithelial keratitis with or without
  pseudodendrites occurs more rarely.
• Disciform keratitis with uveitis of varying
  duration has been reported.

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Ophthalmic herpes zoster

• Is accompanied by keratouveitis that varies in
  severity according to immune status of the
  patient.
• Children with zoster keratouveitis usually have
  benign disease, aged have severe and sometimes
  blinding disease.
• Corneal complications in ophthalmic zoster often
  occur if there is skin eruption in areas supplied
  by branches of the nasociliary nerve.

Vaughan Asburys General Ophthalmology 16th
Edition, 136-137
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Distinguishing features of dendrites associated
with HSV versus VZV
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Treatment

• Intravenous and oral acyclovir have been used
  successfully for treatment of herpes zoster
  ophthalmicus, particularly in immunocompromised
  patients.
• Oral dosage is 800 mg five times daily for 10-14
  days.
• Therapy needs to be started within 72 hours after
  appearance of the rash.

Vaughan Asburys General Ophthalmology 16th
Edition, 136-137