aetiopathogenesis of viral keratitis

1. Aetiopathogenesis of
viral keratitis
CHAIRMAN: PROF. DR. MD. SAIFULLAH
DEPT OF CORNEA, NIO&H
MODERATOR: ASST PROF. DR.FARHAT JAHAN
DEPT OF CORNEA , NIO&H
PRESENTER: DR. SADIA YEASMIN SAKI
FCPS P-2 STUDENT, NIO&H

2. Viral keratitis
Herpes simplex
Varicella zoster
Adenovirus
Others(pox viridae, herpes viridae, papo viridae, picorna viridae, togaviridae)

3. Herpes simplex keratitis
are ubiquitous human pathogen capable of causing both asymptomatic infection & active
disease
Two types: HSV 1: oropharynx
HSV 2: genital organ
Ocular disease typically caused by type 1
Mode of infection:
Humans are the only natural reservoir
HSV 1: close contact, HSV 2: birth canal

4. HERPES SIMPLEX KERATITIS..
VIRAL STRUCTURE:
Double stranded DNA virus

5. Pathogenesis-latency
After peripheral entry into host & primary infection
HSV travel in a retrograde fashion to various ganglia( trigeminal, cervical, sympathetic)
Resides during the lifespan of the host
Once ganglionic presence has been established, active replication in neuron
Latency is established & presence of viral genome within the neuronal cell

6. Pathogenesis-Reactivation
LATS: latency –associated transcripts, a region of viral genome that is retained within host cell
During latency
Produced in large amount during reactivation from latency

7. Reactivation source
After primary infection
Subclinical reactivation: periodical HSV shedding
Clinical reactivation: fever
hormonal change
ultraviolet radiation
trauma
trigeminal injury

8. HSV keratitis..

9. Clinical manifestation
Congenital & neonatal
Primary infection
Recurrent infection

10. Congenital & neonatal ocular herpes
Most congenital cases are acquired: genital herpes in mother
during parturition
HSV-2 for 80% cases
Micropthalmia, retinal dysplasia, optic atrophy & chorioretinitis ( from intrauterine infection)
Ocular manifestation: periocular skin lesion
conjunctivitis
epithelial keratitis
stromal keratitis
cataract

11. Primary infection
After 6 months-maternal anti-HSV Ig G
Acute follicular conjunctivitis
Keratoconjunctivitis
Periocular lymphadenopathy
Periocular & eyelid skin vesicles
Diffuse punctate keartopathy
Corneal vesicles
Primary infection only confined to epithelium due to lack of
previous immunologic stimulus

12. Recurrent ocular herpes
Clinical manifestations:
blepharitis: vesicular lesion involving a focal area
conjunctivitis: recurrent follicular conjunctivitis
HSV keratitis
Iridocyclitis

13. HSV keratitis

14. Infectious epithelial keratitis
Symptoms: discomfort, redness, photophobia, watering, blurring of vision
Stellate lesion: swollen epithelial cell/ vesicle. earliest epithelial lesion
Dendritic ulcer: most common presentation
branching linear lesion, terminal bulbs ,swollen epithelial border
 Geographic ulcer: an enlarged dendritic ulcer that is no longer linear
Marginal ulcer: results from active viral disease,
proximal to limbus with accompanying blood vessel

15. Recurrent ocular herpes..
A) stellate lesion b)bed of dendritic ulcer with fluroscein stain

16. Recurrent ocular herpes..
C) margin of dendritic ulcer, rose Bengal stain d) geographic ulcer

17. Neurotrophic keratopathy
Impaired corneal innervation
Decreased tear secretion
Clinical feature:
punched out epithelial erosion
oval in shape with smooth border

18. Stromal disease
Necrotizing stromal keratitis:
direct viral invasion of stroma
C/F: epithelial defect
stromal necrosis
anterior uveitis ,KP
scarring, vascularization, lipid deposition

19. Stromal disease..
Immune stromal ( interstitial) keratitis
Retained viral antigen within stroma triggers inflammation
 Intact overlying epithelium
C/F: stromal inflammation,infiltration,neovascularization
ghost scarring/ foot prints
wessely ring

20. Endothelitis
Disciform keratitis (endothelitis):
Delayed hypersensitivity reaction
Microcystic epithelial edema,KP
Disc shaped area of stromal edema, central/paracentral
Descemet membrane fold

21. Endothelitis..
Disciform endothelitis

22. Endothelitis..
Diffuse endothelitis

23. Endothelitis..
Linear endothelitis

24. Recurrent ocular herpes..
Iridocyclitis:
Can occur without prior h/o keratitis
Fine KP, AC reaction
Trabeculites-raised IOP

25. Varicella zoster virus
Epidemiology:
Spread by saliva droplets, direct contact with cutaneous lesion
Systemic feature:
Generalized vesicular lesion, fever, malaise, rash. pneumonia ( common complication)
Ocular feature:
vesicular eruption on periocular skin & eyelid, papillary conjunctivitis

26. Herpes zoster ophthalmicus

27. HZO..
First described by Hutchinson in 1865
 Clinical entity caused by reactivation of the latent VZV from trigeminal ganglia with ocular
involvement.
Ophthalmic division of trigeminal nerve mostly affected
Hutchinson sign- vesicles at the side & tip of the nose

28. HZO..
Pathogenesis:
VZV transported from epithelial vesicles to sensory ganglia
Latency period: continuous active transcription
Direct co relation between increasing age & HZO
Reactivation due to inflammation/necrotic change of dorsal root ganglia

29. HZO pathogenesis..
Virus travels along the sensory axons to the skin
Mononuclear infiltration & multinuclear giant cell reaction
Virus enters the eyes via ciliary nerves
Perineuritis & perivasculitis around long & short ciliary nerves &vessels

30. HZO..
General feature:
Prodromal phase: symptom involving affected dermatome
Skin lesion:
painful erythematous area with maculopapular rash
vesicles
pustule , crust
haemorrhagic lesion
Zoster sine herpete

31. HZO..
Ocular feature:
Periocular skin & eyelid: maculopapular rash, vesicular skin eruption,
Conjunctiva: papillary /follicular reaction, hyperemia, and/or pseudomembrane
Sclera: episcleritis, scleritis

32. HZO..
Corneal changes:
Punctate epithelial keratitis- 2 days
Pseudodendritic keratitis : 4-6 days
Anterior stromal keratitis: 10 days
endothelitis: 7 days
Sclerokeratitis: 1 month
Corneal mucous plaques: 2-3 month
Disciform keratitis: 3-4 month
Neurotropic keratopathy: 2 month
Interstitial keratitis: 1-2 years

33. HZO-corneal changes..
PEK – 2day pseudodendrite- 4-6 day

34. HZO..
Nummular keratitis:
Granular sub epithelial deposit surrounded by a halo of stromal haze
Develops 10 days after onset of rash at the site of epithelial lesion

35. HZO-corneal changes..
Endothelitis-7-15 days serpiginious ulceration – I month

36. HZO..
Iridocyclitis:
Anterior uveitis
Sectoral iris ishchemia ,atrophy
Posterior uveitis: progressive retinal necrosis

37. Post herpetic neuralgia
Pain persist for more than one month after the rash has healed
Occur in elderly patient
Constant /intermittent pain, worse at night & aggravated by minor stimuli
M/A: ectopic activity in damaged nociceptive fibers

38. Adenovirus keratoconjunctivitis
adenovirus: double stranded DNA virus
Transmitted by close contact with ocular or respiratory secretions, fomite, or contaminated
swimming pool
Transmission more in populations living in close quarters, contaminated instruments, or eye
drops in physicians office
 systemic feature : upper respiratory tract infection, diarrhoea, hemorrhagic cystitis,
meningoencephalitis.

39. Adenovirus keratoconjunctivitis
Ocular feature:
Epidemic keratoconjunctivitis
Pharyngoconjunctival fever
Non specific follicular conjunctivitis

40. Epidemic keratoconjunctivitis
Serotype AD 8,9,37
C/F:
Bilateral, preceded by upper RTI
Acute watering
Foreign body sensation, photophobia, reduced vision
Lid, conjunctival edema
Follicular, papillary conjunctivitis
Hemorrhage/ membrane formation
Tender preauricular lymph node

41. Epidemic Keratoconjunctivitis
Stage 0: poorly staining minute punctate opacity
Stage 1: fine superficial epithelial keratitis
Stage 2: punctate, slightly raised whitish epithelial lesion.
Stage 3: coarse granular infiltrate within deep epithelium
Stage 4: sub epithelial infiltrate
Stage 5: punctate epithelial granularity

42. Pharyngoconjunctival fever
Serotype AD 3,7
C/F:
Fever, headache
Pharyngitis
Follicular conjunctivitis
Preauricular lymphadenopathy
Mild epithelial keratitis

43. Non specific follicular conjunctivitis
Serotype Ad 1,2,4,5 & 6
Mild conjunctivitis
No keratitis
Self limiting

44. Less common viral corneal infection
poxviridae
Variola virus
Vaccinia virus
Molluscum contagiosum virus
Cytomegalo virus
Rubella virus
Influenza virus