Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Ophthalmology PPT 14 Viral Protozoal Corneal Ulcer Lecture Notes
VIRAL AND PROTOZOAL
KERATITIS
Ophthalmology
HERPES VIRUS
Are ubiquitous human pathogen capable of causing both
asymptomatic infection and active disease
Humans are natural reservoir of HSV
2 types ? HSV 1- oropharynx
HSV 2 ? genital area
Ocular disease typically caused by type 1
Causes primary infection in children and neonates
MODE OF INFECTION:
IP ? 3- 9 days
HSV 1 ? close contact
HSV 2 ? venereal ? birth canal
MECHANISM OF ACTION
HSV (epitheliotropic & cytolytic) binds to one or
more cellular receptor ? heparin sulphate
Virus fuses with cell membrane
Enters the cell and nucleus where the transcription
of viral DNA occurs ? protein
?TG is the most common source of recurrent HSV infection.
?Primary infection may subsequently reactivate by travelling via
ophthalmic division of 5th CN to the eye.
PATHOGENESIS
Factors for reactivation ?
UV rays
Trauma
Heat, abnormal body temperature
Other infectious disease
Emotional disease
Menstrual stress
Steroids, immunosuppresant, PGs
CLINICAL FEATURES
Suspicion of viral keratitis arises if there is
Associated skin lesions, recurrences of these lesions
Stress-induced recurrence
Immuno compromised status
History of contact
Symptomatic eye (Pain ,Photophobia ,Blurred vision,
Tearing ,Redness) with minimal conjunctival and
corneal signs
Superficial dendrites with loss of corneal sensation
CLASSIFICATION OF OCULAR DISEASE
1.Congenital & Neonatal
2. Primary infection
3. Recurrent infection
CONGENITAL AND NEONATAL OCULAR HERPES
May be acquired by one of the three periods :
q Intrauterine (5%)
q Peripartum(10%)
q Postpartum (85%)
Intrauterine infection occurs in 1/300,000 births, with features of
microophthalmia, retinal dysplasia, optic atrophy and
chorioretinitis.
HSV infections in latter two periods are further classified as skin,
eyes, or mouth (SEM) with or without the other involvement seen
in intrauterine infections.
Ocular herpes include one or all: conjunctivitis, epithelial keratitis,
stromal immune reaction, cataract, necrotizing chrioretinitis.
PRIMARY INFECTION
After 6 months ? maternal anti-HSV IgG
Cutaneous involvement-vesicular periocular skin
eruptions , vesicular ulcerative blepharitis
Acute follicular conjunctivitis
Keratoconjuctivitis with non-suppurative
lymphadenopathy
Diffuse punctate keratitis ? that evolves into multiple
scattered micro dendrite figures.
As a rule confined to epithelium clinically ? d/t lack
of previous immunologic stimulus
Treatment-Topical antivirals supported by
antibiotics & cycloplegics
RECURRENT INFECTION
Patients with recurrent herpes have both cellular and
humoral immunity against the virus.
corneal vesicles
dendritic ulcer
geographic
ulcer(amoeboid)
limbal ulcer
(marginal)
CLASSIFICATION OF HSV KERATITIS
The disease may present as 5. Stromal keratitis
any one or a combination Necrotizing stromal keratitis
of the following:
Immune (interstitial) keratitis
1. Blepharoconjuctivitis
Immune rings
2. Episcleritis, scleritis
Limbal vasculitis
3. Infectious epithelial
Disciform keratitis
keratitis ?(IEK)
6. Endothelitis
4. Neurotrophic
keratopathy
Disciform
Diffuse
Linear
7. Iridocyclitis
8. Trabeculitis
Herpes simplex epithelial keratitis
MC PRESENTATION
? Dendritic ulcer with terminal bulbs ? May enlarge to become geographic
? Stains with fluorescein
In herpes, corneal sensation is reduced in approx 70 % of the patient.
Treatment
? Aciclovir 3% ointment x 5 daily
?
2-3wks
Ganciclovir ophthalmic gel 0.15% - 5 times daily
? Supported by antibiotics and cycloplegics
? Debridement if non-compliant
D/D OF DENDRITIC KERATITIS
? Herpes zoster dendritic keratitis (pseudodendrites)
? Acanthamoeba keratitis
? Contact lens keratopathy
? Antiviral toxicity
Herpes simplex disciform keratitis
Signs
Associations
? Central epithelial and stromal oedema ? Occasionally surrounded by
? Folds in Descemet membrane
Wessely ring
? Small keratic precipitates
Treatment - topical steroids (pred 1% or dexa 0.1%)+ with antiviral cover
COTND....
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
Neurotrophic keratopathy
( Metaherpetic)
Damage to gasserian
ganglion
Impaired corneal
innervations
Decreased tear secretion
Excess use of antivirals
Signs ?
Irregular cornea with loss of Rx-Stop all unnecessary medications
corneal lustre
Gentle debridement of boggy epithelium
Characterized by persistent Artificial tears
epithelial defect
Mild steroid :If active stromal keratitis +ve
Therapeutic soft CL
Oval in shape with gray,
Doxycycline 100mg PO once daily to inhibit
thickened smooth borders
collagenase
Cycloplegics: if iritis is +ve
Tarsorrhaphy to treat chronic exposure
Cyanoacrylate glue ? if perforation occurs
PRIMARILY A CLINICAL DIAGNOSIS
LABORATORY INVESTIGATIONS
Specific tests
Viral culture (gold standard)
Antigen detection ? Immunofluorescence, Elisa
PCR
Serology
Non-specific tests ?
Cytology --Giemsa stain (multinucleated giant cells )
--Papanicolaou stain - intranuclear eosinophilic
inclusion bodies
Electron microscopy
INDICATIONS FOR ORAL ACYCLOVIR
Oral Acyclovir
Linear endothelitis
Diffuse endothelitis
Severe trabeculitis
Immunocompromised patients
Paediatric patients refractory to topical
Prophylaxis for post-PKP with h/o HSV
Prophylaxis against recurrent IEK
PROPHYLAXIS AGAINST RECURRENCE
::Frequent recurrent infection if b/l or involving an only
eye
::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
(for immunocompromised pt)
VARICELLA ZOSTER VIRUS
Incidence & epidemiology:
I. Spread by saliva droplets, or direct contact with
infected rash.
II. The maculopapular rash appears in successive crops,
lesions of various stages present simultaneously.
III. Contagious period approx 1 day before rash &
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.
CLINICAL DISEASE
Congenital varicella syndrome
qIf mother contracts varicella during first or second
trimester of pregnancy.
qOcular findings ~ chorioretinits, optic nerve
atrophy or hypoplasia, congenital cataract and
Horner Syndrome.
qNo specific treatment.
qVaccinate all women with no history of previous
varicella.
HZO
?First described by
Hutchinson in 1865
?MC involves ophthalmic
division of 5th nerve
?Frontal branch is MC
involved
?Nasociliary involvement
? 76% ocular involvement
?Hutchinson's sign ?
vesicles at the side &
tip of nose precedes
HZO
?HZO lies dormant in TG
Herpes zoster keratitis
Acute epithelial keratitis
Nummular keratitis
? Develops in about 50% within ? Develops in about 30% within
2 days of rash
10 days of rash
? Small, fine, dendritic or stellate
? Multiple, fine, granular deposits
epithelial lesions
just beneath Bowman membrane
? Tapered ends without bulbs ? Halo of stromal haze
? Resolves within a few days
? May become chronic
OPHTHALMIC
COMPLICATIONS
Ramsay Hunt syndrome ?
7th nerve palsy + loss of taste
over ant 2/3rd tongue +
earpain + vesicles in external
auditory canal or pinna
DIAGNOSIS
Diagnosis based on acute or recent history of systemic
ds with ocular or periocular involvement with
vesicles.
INVESTIGATIONS- vesicular fluid for PCR, immunomicroscopy
TREATMENT
ACTIVE DISEASE
1.
Antivirals( treat for 7 days , starting within 72 hrs) Famcyciclovir 500mg
PO TDS
Valacyclovir 1 g PO TDS
Acyclovir 800mg PO 5t/d
2.
Lesions of lid, conjunctiva or cornea ( dendritic or rarely geographical
keratitis) ? topical AV (trifluridine applied 9t/d * 7-10 days) plus an topical
AB.
3. Late onset immune stromal ds treated similar to stromal herpes infection.
4. Pain prevention-
TCA's( eg nortryptyline, desipramine) 25-75 mg PO * 3months
Nonnarcotic or short term narcotic analgesic .
5. Immunocompromised patients with any zoster ?
I.V Acyclovir 15 ? 20 mg/kg/day
ADENOVIRUS
KERATOCONJUCTIVITIS
Medium-sized (90?100 nm),
nonenveloped (without an outer lipid bilayer)
icosahedral viruses composed of a nucleocapsid and a
double-stranded linear DNA genome.
OCULAR MANIFESTATIONS
1. Epidemic keratoconjunctivits
2. Pharyngoconjunctival fever
3. Nonspecific follicular conjunctivitis
4. Chronic adenoviral keratoconjunctivitis
EPIDEMIC KERATOCONJUCTIVIS
Serotype AD 8, 19, & 37.
Most serious adenoviral ocular illness
In young adults during the fall and winter months
U/L in 2/3rd pt
IP 8 days
Sign and symptoms:
Acute tearing, FBS, photophobia, followed by lid
and conjuctival edema and hyperemia, follicular and
papillary conjuctival response with or without hge or
membrane formation, & tender LN's
PHARYNGOCONJUCTIVAL CHRONIC ADENOVIRAL
FEVER
KERATOCONJUCTIVITIS
Serotype Ad 3 and 7
Serotype Ad 2,3,4 and 19.
Similar to EKC except that
Uncommon, often
the keratitis is usaully mild
recognized cause of ant
and b/l, and subepithelial
segment inflammatory and
infiltrates are less frequent
scarring ds.
and more transient.
DIAGNOSIS & TREATMENT
Cytologic scrappings - mixed lymphocytic and neutrophil
infiltrate and degenerated epithelial cells.
Giemsa staining may reveal early eosinophillic intranuclear
bodies.
Antivirals are ineffective , except cidofovir.
Topicals NSIAD'S : relief of inflammation. No effect onviral
replication or appearance of corneal infiltrates.
Cycloplegics as needed for iritis.
Topical antibiotic ointment to lubricate and protect the
cornea in presence of membranes.
Ice packs, antipyretics and dark glasses as needed.
ACANTHAMOEBA
Genus Acanthamoeba:-
a family of free-living,
ubiquitous cyst-forming
protozoans.
? Life cycle:- 2 forms
? Generally rare infection
characterized by
periodic outbreaks
Acanthamoeba keratitis
? Contact lens wearers at particular risk
? Symptoms worse than signs
? Pain disproportionate to clinical signs in early presentation
CORNEAL
SCRAPINGS
Epithelial scrapings for
LM
?
H & E stain
?
Giemsa
Small, patchy anterior
Perineural infiltrates
?
PAS stain
stromal infiltrates
(radial keratoneuritis)
?
CFW stain
?
Acridine orange
stain
CULTURE
Non-nutrient agar with
e.coli
Ulceration, ring abscess
Stromal opacification
& small, satellite lesions
Treatment
-Medical therapy given for 135 days
-Biguanides(chlorhexidine or polyhexamethylenebiguanide
(0.02%) effective against both forms
This post was last modified on 07 April 2022