HSK Flashcards
Where does HSV go to establish latency?
The Trigeminal ganglion
What 3 branches does the trigeminal ganglion branch out to?
- Ophthalmic (eyes)
- Maxillary
- Mandibular (mouth)
What are LATs?
Latency Associated Transcripts
- LATs facilitate latency through repression of infected cell polypeptide 0 (ICP0) which dismantles normal cell transcription/translation and promotes viral replication.
-LATs also promote neuronal survival by blocking apoptosis, so infected neurons survive
What is Corneal Hypoesthesia?
Decreased corneal sensitivity
What can trigger HSK reactivation?
Fever Cold URT Infection UV exposure Fatigue Menstruation Stress
What are the Symptoms of Primary Infection of Herpes Simplex?
- 65% show no signs/symptoms
- symptoms usually are similar to any other viral infection
- Acute conjunctivitis (lasts <2 weeks)
- SPK
What are the classifications of HSV Keratitis?
- Epithelial Keratitis (Dendritic epithelial ulcer or Geographic epithelial ulcer
- Stromal Keratitis With/Without Ulceration (Non-nectrotixing, Interstitual, immune stromal keratitis)
- Endothelial Keratitis (Disciform Keratitis)
What are the common signs/symptoms of HSV Epithelial Keratitis?
Symptoms
- Unilateral Redness
- Watery DIscharge
- Photophobia
- Irritation
Signs (in order of progression)
- Raised epithelial lesion
- SPK
- Dendritic Ulcer
- Geographic Ulcer
What is the Treatment of HSV Epithelial Keratitis?
No treatment
- 1st Ophthalmic occurrence the resolution is in about 17 days
- If recurrent resolution in about 28 days.
Treatment
- Anti-viral, Aciclovir 3% ointment q5h for 14 days, however treatment should continue for 3 days after healing.
What is the review plan for HSV Epithelial Keratitis?
- 24-48 Review
- Then every 2-3 days up to 14 days.
- If healing isnt seen, reconsider diagnosis, maybe medication toxicity
What is the prescribed dosage for oral aciclovir?
400mg po (orally) q5h for 7-10 days HEDS study has found both oral and topical treatment to be of equal efficacy.
Why should you never use a steroid on an active HSV ucler?
It promotes deeper HSV infection, helping epithelial level keratitis become stromal level keratitis.
How can you tell the difference between active and inactive stromal keratitis?
Active
- stromal inflammation with infiltration
- oedema
- vascularisation
- AC reaction
Inactive
- Stromal Scars
- Stromal thinning
- Ghost Vessels
- KP
What causes the Stromal Inflammation in HSV stromal keratitis without ulceration?
TYPE III Antibody-Antibody Hypersensitivity Reaction, which leasds to immune precipitation in the stroma and a Diffuse inflammatory Wessely Ring infiltrate
TYPE IV Cell Mediated Hypersensitvity reaction where the T lymphocytes respond to the Antigen in the stroma, and this takes up to a couple days to happen.
What are some triggers for HSV keratitis?
Conditions that reduce immune systems efficacy
immunoCOMPROMISED
- Organ transplant
- Diabetes mellitus
- Measels
- HIV
ImmunoDEPRESSION
- Fever
- Stress
- Menstruation
- Severe weather events
What has the HEDs study stated as NON triggers for HSV keratitis?
- Gender
- Age
- Ethnicity
- History of Non Ocular HS disease
- Contact Lens Wear (no association seen contact lens wear and HSV keratitis recurrence)
What are some Ocular Triggers for HSV keratitis?
Increase susceptibility
- Prostaglandin Analogues
- Corticosteroids
- Angiogenesis Inhibitors
Local Trauma and Inflammation
- Laser refractive surgery
- Cataract Surgery
- Ocular Steroids
What is the efficacy of short term high dose acyclovir for the recurrence of HSV keratitis according to the HEDs study?
400mg acyclivor orally twice a day has shown a 50% less reoccurance in the treated group vs control group.
What is the treatment for stromal keratitis is there is an epithelial defect seen?
Use anti-viral (aciclovir q5h) BEFORE steroid treatment is started for stromal disease.
When Ucler is healed taper with prophylactic dose (over week) in conjunction with steroid
