A single-center, retrospective study conducted at Johannes Gutenberg University in Mainz, Germany, evaluated the prevalence of herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) DNA in relation to the graft survival rate in recipient corneas following penetrating keratoplasty (PK).
These herpesviruses are known to cause herpetic keratitis (HK)—one of the top causes of infectious corneal vision impairment. (via)
Tell me about the study.
Researchers analyzed data from a large cohort of consecutive patients who underwent PK between January 2020 and June 2021. The study included 112 eyes of 112 consecutive patients who underwent PK. At the time of PK, 91 eyes (81.25%) had no history of HK and 21 (18.75%) eyes did.
The clinical routine included performing HSV-1 and VSV polymerase chain reaction (PCR) on all excised corneal buttons in the cohort, regardless of the primary clinical diagnosis.
What treatments did study participants undergo?
Patients with a history of HK received around 4 weeks of preoperative prophylactic topical and perioral antiviral treatment. They were assigned a regimen of acyclovir/ganciclovir ophthalmic ointment (1-5 times daily), and acyclovir (5 x 400-800 mg)/valacyclovir (2 x 500-1000 mg).
After the PK, all patients with a preoperative history of HK, or with positive HSV-1 or VZV DNA PCR assays results from corneal biopsies, received topical and perioral antiviral treatment.
This postoperative treatment included acyclovir/ganciclovir ophthalmic ointment (1-5 times daily), and acyclovir 400 mg (5 times daily/) for the first 4 weeks with a maintenance dose of valacyclovir 500 mg (2-4 times daily) for one year after.
Anything else?
Additionally, patients underwent a standard PK postoperative treatment of dexamethasone 1.3 mg/mL or prednisolone acetate 10.5 mg/mL eye drops 6 times daily with a monthly reduction to one maintenance dose per day for a total of at least 1 year, preservative-free antibiotic eye drops 4 times daily, and preservative-free artificial tears 6 times daily.
What did the study find?
The corneas of 91 patients with no history of HK tested positive for HSV-1 DNA in 12 eyes (13.2%) and for VZV DNA in 3 eyes (3.3%). Two eyes (2.2%) tested positive for the presence of both HSV-1 and VZV DNA.
The recipient corneas of 21 patients with a preoperative history of HK tested positive for HSV-1 DNA in 13 eyes (61.9%) and VSV DNA in 1 eye (4.8%).
All patients who tested positive for herpesvirus DNA, and had no history of HK prior to the PK, received antiherpetic treatment and had a 100% graft survival rate after 1 year.
Tell me more.
Researchers noted an increase in visual acuity without correction at the 3-month and 1-year follow-ups. In both groups, preop visual acuity was logMar 1.9 (1.3, 2.3), and for the group with no history of HK, at the 1-year mark, visual acuity improved to logMar 0.7 (0.3, 1.6). In the group with a history of PK, visual acuity improved to logMar 1.0 (0.7, 1.3).
Interestingly, the herpesvirus PCR test results of the swab and biopsy were congruent in 73.3% of eyes.
However, 11.1% of eyes had a positive herpesvirus DNA swab and a negative herpesvirus DNA biopsy result, while 17.8% of eyes had a negative herpesvirus DNA swab but a positive herpesvirus DNA biopsy result.
What does this mean?
The results of this study suggest the need for routine HSV-1 and VZV PCR screening in all explanted corneas—regardless of clinical suspicion—to detect, treat, and prevent possible recurrence of herpetic infection in corneal grafts and support graft survival.
Take home?
Patients with no clinical signs or history of HK and an undetected primary infection are at risk for complications after PK, either through reactivation due to neuronal or corneal latency, or through the transmission of corneal grafts.
For patients with a history of HK, adequate topical and systemic antiherpetic treatment is required, along with immunosuppressive topical steroid therapy to ensure graft survival.