How can you differentiate this condition from similar ones?
Herpes simplex virus type 1 can masquerade as conjunctivitis, blepharitis, neurotropic keratitis, herpes zoster keratitis, adenovirus keratitis, Thygeson’s SPK, recurrent corneal erosion, anterior basement membrane dystrophy and acanthamoeba keratitis.
Here’s a look at the symptoms, clinical signs and the diagnosis/management of the most common HSV-1 ocular conditions. Do you know which symptom and clinical sign differentiate it? (See the answer on p.51.)
HSV-1 infections can cause little to no symptoms after the initial exposure. That said, the symptoms common to all HSV-1 ocular conditions are:
- Decreased corneal sensitivity
- Decreased VA
- Foreign-body sensation
- Anterior chamber cell and/or flare
- Corneal endothelial edema and keratic precipitates on the endothelial cells
- Corneal stromal scars, thinning, edema and infiltrates
- Corneal epithelial defects (epithelial staining may appear dendritic, irregular, geographic or punctate), corneal dellen and corneal neovascularization
- Dendritic epithelial lesion with terminal bulbs, often associated with ulceration
- Eyelid rash and blisters
- Follicular conjunctivitis
- Neurotrophic keratitis
|Herpes simplex unspec. ophthal. complication||B00.50|
|Herpes viral iridocyclitis||B00.51|
|Herpes viral keratitis||B00.52|
|Herpes simplex disciform keratitis||B00.52|
|Other herpes viral disease of eye||B00.59|
|Post herpetic trigeminal neuralgia||B02.22|
The following aid in diagnosis:
- Case history. Patient reports of cold sores (recurrent episodes), accompanied by recurrent red eye, recent topical steroid use, recent fever and UV exposure indicate you’re likely dealing with an HSV-1 ocular condition.
- External photography (CPT 92285).
- Corneal culture (CPT 65430). Check for sensitivity and specificity for HSV-1 in atypical or non-resolving keratitis.
- Corneal sensitivity. Spin a small cotton fiber from a cotton swab, lightly touch each cornea, and have the patient compare sensitivity between the non-affected and affected eye.
- Slit lamp exam with corneal staining (NaFl or Rose Bengal).
For management, you can use:
- Amniotic membranes (CPT 65778). Placed on the cornea in office and used with other HSV-1 treatments, these have regenerative healing properties that can treat non-resolving epithelial defects (in which the condition has turned neurotropic) as well as cases in which infection and inflammation have resulted in visually significant scarring,
- Corneal debridement (CPT 65435). This may help decrease the viral load and remove some of the infected tissue, but should not be used alone, as it is believed to be a weak treatment option.
- Oral antivirals. In cases of primary HSV and severe cases of stromal keratitis, oral acyclovir (Zovirax, GlaxoSmithKline) should be dosed 400 mg five times a day. (Many doctors use valacyclovir [Valtrex, GlaxoSmithKline] more frequently because it has a reduced dosing schedule and is a prodrug (well tolerated.) In cases in which recurrence is more common or the patient has had multiple episodes in a short period, consider an oral antiviral as prophylaxis with valacyclovir, dosed at 500 mg t.i.d. for seven to 10 days, and famciclovir (Famvir, Novartis), dosed at 250 mg three times a day for seven to 10 days. Even lower dosages, such as 250 mg or 500 mg can be used daily for months for recurring and chronic cases of HSV as well as prior to and after surgery.
Many HSV patients take topical steroids after surgeries. These can decrease the immune response, allowing the virus to reactivate. Oral antivirals, such as those often prescribed prophylactically, help decrease the chance of HSV reactivation in these patients.
- Topical antivirals. Two topical FDA-approved treatments are available. trifluridine 1% (Viroptic, Pfizer), dosed one-drop every two hours while awake until the corneal ulcer has re-epithelialized. Then, decrease to one-drop every four hours for the next seven to 10 days to decrease active viral replication. The drug must be refrigerated for the best efficacy and can burn upon instillation. The other drug is ganciclovir (Zirgan, Bausch + Lomb), which is dosed five times a day until the corneal ulcer is healed; then three times a day for seven days until viral replication has stopped. Visual blur is a side effect.
As primary eye care providers, O.D.s will routinely see patients who have HSV-1 ocular conditions. To catch this infection early, know the differentiating symptoms and clinical signs and the needed diagnostic tools. OM
Special thanks to Shannon Leon, O.D., for reviewing this article.
ANSWER: Decreased corneal sensitivity and dendritic epithelial lesion.