Treatment of Nummular Keratitis Following HSV Keratitis
Nummular keratitis following HSV infection requires combination therapy with topical corticosteroids (to address the immune-mediated inflammation) plus concurrent oral antiviral prophylaxis (to prevent viral reactivation), as this represents a stromal/immune-mediated complication rather than active epithelial disease. 1, 2
Understanding the Clinical Context
Nummular keratitis represents subepithelial immune infiltrates that develop after HSV epithelial keratitis has resolved—this is a stromal/immune-mediated process, not active viral replication in the epithelium. 3, 4 The key distinction is critical because:
- Active epithelial HSV keratitis is an absolute contraindication to corticosteroids (they potentiate viral replication) 1
- Post-infectious nummular keratitis is an immune-mediated stromal disease that requires anti-inflammatory treatment 3
Primary Treatment Regimen
Topical Corticosteroid Therapy
- Initiate topical corticosteroid therapy (prednisolone phosphate 1% or equivalent) with gradual tapering based on clinical response 5, 3
- The frequency should start at 4-6 times daily and taper slowly over weeks to months to prevent rebound inflammation 5
Mandatory Concurrent Oral Antiviral Prophylaxis
- Always prescribe oral antivirals concurrently when using topical corticosteroids for HSV stromal disease: acyclovir 400 mg twice daily, valacyclovir 500 mg twice daily, or famciclovir 250 mg twice daily 1, 2
- This prophylaxis prevents viral reactivation triggered by corticosteroid-induced immunosuppression 6, 4
Critical Management Principles
Before Initiating Corticosteroids
- Confirm no active epithelial disease via slit-lamp examination with fluorescein staining—look specifically for dendritic or geographic ulcers 1, 6
- If any epithelial defect is present, treat as active epithelial keratitis first with topical ganciclovir 0.15% gel 3-5 times daily PLUS oral antivirals, and absolutely avoid corticosteroids 1
Monitoring During Treatment
- Schedule follow-up within 1 week initially, then every 2-4 weeks during tapering 1, 2
- At each visit, measure visual acuity and perform slit-lamp biomicroscopy with fluorescein to detect epithelial breakthrough (occurs in 4.6% of cases despite prophylaxis) 6
- Monitor intraocular pressure at every visit, as corticosteroid-induced glaucoma is a significant risk 5
Alternative Immunomodulatory Approach
Topical Cyclosporine A
- Consider topical cyclosporine A 0.05-2% as an alternative or adjunct to corticosteroids, particularly in patients with:
- Cyclosporine A demonstrated resolution in 71% of non-necrotizing stromal keratitis cases when combined with acyclovir 5
- Always maintain concurrent oral antiviral therapy (acyclovir ointment or oral antivirals) when using cyclosporine 5
Common Pitfalls to Avoid
- Never use corticosteroids without concurrent oral antiviral prophylaxis—this dramatically increases the risk of epithelial disease recurrence 6, 3
- Never taper corticosteroids too rapidly—this causes rebound inflammation and treatment failure; taper over weeks to months 5
- Never use topical antivirals alone for prophylaxis during corticosteroid treatment—trifluridine prophylaxis showed no significant benefit and caused toxic epitheliopathy in 4.2% of patients 6
- Patients with prior history of HSV epithelial keratitis have higher risk of recurrence during stromal treatment and require closer monitoring 6
Long-Term Considerations
- Patients with recurrent nummular keratitis may require prolonged low-dose corticosteroid maintenance (as low as 0.25% prednisolone once weekly to once daily) with continuous oral antiviral prophylaxis 7
- Consider long-term oral antiviral suppression (acyclovir 400 mg twice daily or valacyclovir 500 mg daily) to prevent future recurrences, especially in patients with frequent relapses 4