Download MBBS Ophthalmology PPT 14 Viral Protozoal Corneal Ulcer Lecture Notes

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VIRAL AND PROTOZOAL

KERATITIS

Ophthalmology

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HERPES VIRUS

Are ubiquitous human pathogen capable of causing both

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asymptomatic infection and active disease

Humans are natural reservoir of HSV
2 types ? HSV 1- oropharynx

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HSV 2 ? genital area

Ocular disease typically caused by type 1
Causes primary infection in children and neonates

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MODE OF INFECTION:
IP ? 3- 9 days
HSV 1 ? close contact
HSV 2 ? venereal ? birth canal

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MECHANISM OF ACTION

HSV (epitheliotropic & cytolytic) binds to one or

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more cellular receptor ? heparin sulphate

Virus fuses with cell membrane
Enters the cell and nucleus where the transcription

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of viral DNA occurs ? protein

?TG is the most common source of recurrent HSV infection.

?Primary infection may subsequently reactivate by travelling via

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ophthalmic division of 5th CN to the eye.

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PATHOGENESIS

Factors for reactivation ?
UV rays

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Trauma
Heat, abnormal body temperature
Other infectious disease
Emotional disease
Menstrual stress

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Steroids, immunosuppresant, PGs

CLINICAL FEATURES

Suspicion of viral keratitis arises if there is

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Associated skin lesions, recurrences of these lesions
Stress-induced recurrence
Immuno compromised status
History of contact
Symptomatic eye (Pain ,Photophobia ,Blurred vision,

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Tearing ,Redness) with minimal conjunctival and

corneal signs

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Superficial dendrites with loss of corneal sensation

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CLASSIFICATION OF OCULAR DISEASE

1.Congenital & Neonatal

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2. Primary infection

3. Recurrent infection

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CONGENITAL AND NEONATAL OCULAR HERPES

May be acquired by one of the three periods :
q Intrauterine (5%)
q Peripartum(10%)

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q Postpartum (85%)

Intrauterine infection occurs in 1/300,000 births, with features of

microophthalmia, retinal dysplasia, optic atrophy and

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chorioretinitis.

HSV infections in latter two periods are further classified as skin,

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eyes, or mouth (SEM) with or without the other involvement seen

in intrauterine infections.

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Ocular herpes include one or all: conjunctivitis, epithelial keratitis,

stromal immune reaction, cataract, necrotizing chrioretinitis.

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PRIMARY INFECTION

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After 6 months ? maternal anti-HSV IgG
Cutaneous involvement-vesicular periocular skin

eruptions , vesicular ulcerative blepharitis

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Acute follicular conjunctivitis
Keratoconjuctivitis with non-suppurative

lymphadenopathy

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Diffuse punctate keratitis ? that evolves into multiple

scattered micro dendrite figures.

As a rule confined to epithelium clinically ? d/t lack

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of previous immunologic stimulus

Treatment-Topical antivirals supported by

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antibiotics & cycloplegics

RECURRENT INFECTION

Patients with recurrent herpes have both cellular and

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humoral immunity against the virus.

corneal vesicles

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dendritic ulcer

geographic

ulcer(amoeboid)

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limbal ulcer

(marginal)

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CLASSIFICATION OF HSV KERATITIS

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The disease may present as 5. Stromal keratitis

any one or a combination Necrotizing stromal keratitis

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of the following:

Immune (interstitial) keratitis

1. Blepharoconjuctivitis

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Immune rings

2. Episcleritis, scleritis

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Limbal vasculitis

3. Infectious epithelial

Disciform keratitis

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keratitis ?(IEK)

6. Endothelitis

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4. Neurotrophic

keratopathy

Disciform

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Diffuse
Linear
7. Iridocyclitis
8. Trabeculitis

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Herpes simplex epithelial keratitis

MC PRESENTATION

? Dendritic ulcer with terminal bulbs ? May enlarge to become geographic

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? Stains with fluorescein

In herpes, corneal sensation is reduced in approx 70 % of the patient.

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Treatment

? Aciclovir 3% ointment x 5 daily

?

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2-3wks

Ganciclovir ophthalmic gel 0.15% - 5 times daily

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? Supported by antibiotics and cycloplegics

? Debridement if non-compliant

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D/D OF DENDRITIC KERATITIS

? Herpes zoster dendritic keratitis (pseudodendrites)

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? Acanthamoeba keratitis

? Contact lens keratopathy

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? Antiviral toxicity

Herpes simplex disciform keratitis

Signs

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Associations

? Central epithelial and stromal oedema ? Occasionally surrounded by
? Folds in Descemet membrane

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Wessely ring

? Small keratic precipitates

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Treatment - topical steroids (pred 1% or dexa 0.1%)+ with antiviral cover


COTND....

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Oral (in immunodeficient or children)
:: Acyclovir 400 mg PO 5t/d * 14 days, or
::Famcyclovir 500 mg PO twice daily for 14 days, or
:: Valacyclovir 500 mg PO twice daily for 14 days, or

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Neurotrophic keratopathy

( Metaherpetic)

Damage to gasserian

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ganglion

Impaired corneal

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innervations

Decreased tear secretion
Excess use of antivirals
Signs ?

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Irregular cornea with loss of Rx-Stop all unnecessary medications

corneal lustre

Gentle debridement of boggy epithelium

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Characterized by persistent Artificial tears

epithelial defect

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Mild steroid :If active stromal keratitis +ve

Therapeutic soft CL

Oval in shape with gray,

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Doxycycline 100mg PO once daily to inhibit

thickened smooth borders

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collagenase

Cycloplegics: if iritis is +ve

Tarsorrhaphy to treat chronic exposure

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Cyanoacrylate glue ? if perforation occurs

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PRIMARILY A CLINICAL DIAGNOSIS

LABORATORY INVESTIGATIONS

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Specific tests
Viral culture (gold standard)
Antigen detection ? Immunofluorescence, Elisa
PCR
Serology

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Non-specific tests ?
Cytology --Giemsa stain (multinucleated giant cells )
--Papanicolaou stain - intranuclear eosinophilic

inclusion bodies

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Electron microscopy

INDICATIONS FOR ORAL ACYCLOVIR

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Oral Acyclovir
Linear endothelitis
Diffuse endothelitis
Severe trabeculitis
Immunocompromised patients

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Paediatric patients refractory to topical
Prophylaxis for post-PKP with h/o HSV
Prophylaxis against recurrent IEK

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PROPHYLAXIS AGAINST RECURRENCE

::Frequent recurrent infection if b/l or involving an only

eye

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::Post ?PK patients with history of HSV keratitis
Tab acyclovir 400 mg BD * 12- 18 months
Tab famcyclovir 250 mg OD * 12 -18 months
Valacyclovir 500mg OD * 12 - 18 months

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(for immunocompromised pt)

VARICELLA ZOSTER VIRUS

Incidence & epidemiology:

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I. Spread by saliva droplets, or direct contact with

infected rash.

II. The maculopapular rash appears in successive crops,

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lesions of various stages present simultaneously.

III. Contagious period approx 1 day before rash &

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continues approx 1 week after app of each crop of

lesion or until the cutaneous sores crust over.

IV. IP: 12- 17 days after contact.

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CLINICAL DISEASE

Congenital varicella syndrome

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qIf mother contracts varicella during first or second

trimester of pregnancy.

qOcular findings ~ chorioretinits, optic nerve

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atrophy or hypoplasia, congenital cataract and

Horner Syndrome.

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qNo specific treatment.
qVaccinate all women with no history of previous

varicella.

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HZO

?First described by

Hutchinson in 1865

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?MC involves ophthalmic

division of 5th nerve
?Frontal branch is MC

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involved
?Nasociliary involvement

? 76% ocular involvement

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?Hutchinson's sign ?

vesicles at the side &

tip of nose precedes

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HZO

?HZO lies dormant in TG

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Herpes zoster keratitis

Acute epithelial keratitis

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Nummular keratitis

? Develops in about 50% within ? Develops in about 30% within

2 days of rash

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10 days of rash

? Small, fine, dendritic or stellate

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? Multiple, fine, granular deposits

epithelial lesions

just beneath Bowman membrane

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? Tapered ends without bulbs ? Halo of stromal haze

? Resolves within a few days

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? May become chronic

OPHTHALMIC

COMPLICATIONS

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Ramsay Hunt syndrome ?

7th nerve palsy + loss of taste

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over ant 2/3rd tongue +

earpain + vesicles in external

auditory canal or pinna

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DIAGNOSIS

Diagnosis based on acute or recent history of systemic

ds with ocular or periocular involvement with

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vesicles.

INVESTIGATIONS- vesicular fluid for PCR, immunomicroscopy

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TREATMENT

ACTIVE DISEASE

1.

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Antivirals( treat for 7 days , starting within 72 hrs) Famcyciclovir 500mg

PO TDS

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Valacyclovir 1 g PO TDS

Acyclovir 800mg PO 5t/d

2.

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Lesions of lid, conjunctiva or cornea ( dendritic or rarely geographical

keratitis) ? topical AV (trifluridine applied 9t/d * 7-10 days) plus an topical

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AB.

3. Late onset immune stromal ds treated similar to stromal herpes infection.

4. Pain prevention-

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TCA's( eg nortryptyline, desipramine) 25-75 mg PO * 3months

Nonnarcotic or short term narcotic analgesic .

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5. Immunocompromised patients with any zoster ?

I.V Acyclovir 15 ? 20 mg/kg/day
ADENOVIRUS

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KERATOCONJUCTIVITIS

Medium-sized (90?100 nm),
nonenveloped (without an outer lipid bilayer)

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icosahedral viruses composed of a nucleocapsid and a

double-stranded linear DNA genome.

OCULAR MANIFESTATIONS

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1. Epidemic keratoconjunctivits
2. Pharyngoconjunctival fever
3. Nonspecific follicular conjunctivitis
4. Chronic adenoviral keratoconjunctivitis

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EPIDEMIC KERATOCONJUCTIVIS

Serotype AD 8, 19, & 37.
Most serious adenoviral ocular illness
In young adults during the fall and winter months

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U/L in 2/3rd pt
IP 8 days
Sign and symptoms:

Acute tearing, FBS, photophobia, followed by lid

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and conjuctival edema and hyperemia, follicular and

papillary conjuctival response with or without hge or

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membrane formation, & tender LN's
PHARYNGOCONJUCTIVAL CHRONIC ADENOVIRAL

FEVER

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KERATOCONJUCTIVITIS

Serotype Ad 3 and 7

Serotype Ad 2,3,4 and 19.

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Similar to EKC except that

Uncommon, often

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the keratitis is usaully mild

recognized cause of ant

and b/l, and subepithelial

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segment inflammatory and

infiltrates are less frequent

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scarring ds.

and more transient.

DIAGNOSIS & TREATMENT

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Cytologic scrappings - mixed lymphocytic and neutrophil

infiltrate and degenerated epithelial cells.

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Giemsa staining may reveal early eosinophillic intranuclear

bodies.

Antivirals are ineffective , except cidofovir.

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Topicals NSIAD'S : relief of inflammation. No effect onviral

replication or appearance of corneal infiltrates.

Cycloplegics as needed for iritis.

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Topical antibiotic ointment to lubricate and protect the

cornea in presence of membranes.

Ice packs, antipyretics and dark glasses as needed.

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ACANTHAMOEBA

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Genus Acanthamoeba:-

a family of free-living,

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ubiquitous cyst-forming

protozoans.

? Life cycle:- 2 forms

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? Generally rare infection

characterized by

periodic outbreaks

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Acanthamoeba keratitis

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? Contact lens wearers at particular risk

? Symptoms worse than signs

? Pain disproportionate to clinical signs in early presentation

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CORNEAL

SCRAPINGS

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Epithelial scrapings for

LM

?

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H & E stain

?

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Giemsa

Small, patchy anterior

Perineural infiltrates

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?

PAS stain

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stromal infiltrates

(radial keratoneuritis)

?

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CFW stain

?

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Acridine orange

stain

CULTURE

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Non-nutrient agar with

e.coli

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Ulceration, ring abscess

Stromal opacification

& small, satellite lesions

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Treatment

-Medical therapy given for 135 days

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-Biguanides(chlorhexidine or polyhexamethylenebiguanide

(0.02%) effective against both forms