We appreciate the interest and comments of Gatzioufas and associates concerning our article, “In Vivo Analysis of Stromal Integration of Multilayer Amniotic Membrane Transplantation in Corneal Ulcers,” and for bringing the important point of amniotic membrane transplantation in manifest or suspect herpetic keratitis to the readers’ attention. As correctly pointed out by the authors, persistent corneal epithelial defects and sterile corneal ulcers and melting often may be related to the protean clinical expression of herpetic infection of the eye.
In our study, we enrolled a series of patients with progressive corneal stromal sterile ulceration, nonresponsive to conservative treatments, after a detailed clinical and microbiologic examination to rule out microbial infections and active herpetic keratitis. Three patients belonging to the study group were affected by stromal neurotrophic ulcerations secondary to previous episodes of recurrent stromal herpes simplex-related keratitis, but signs of active herpetic infections were absent at the time of multilayered amniotic membrane transplantation and thereafter during the entire follow-up period (1 year).
We do agree with the authors that, on suspicion of epithelial herpetic eye disease, clinicians should use transplantation of the amniotic membrane onto the ocular surface or inside the corneal stroma with particular precaution. However, it is reasonable to suppose that herpes simplex viruses need the presence of a viable amniotic epithelial layer to spread out by using the amniotic membrane as a substrate. The amniotic membrane generally used is cryopreserved. It has been shown that cryopreservation significantly impairs viability of amniotic membrane epithelial cells, although cell morphologic features are retained. Moreover, it has been demonstrated previously that after transplantation, an amniotic membrane epithelial layer of presumably nonviable cells is retained and that these epithelial cells undergo progressive degradation over a few-week period after transplantation, as confirmed by our recent investigation. One would suppose that after in situ degradation of the amniotic epithelial cells, after transplantation, viral epithelial diffusion may originate, in case of epithelial keratitis recurrences, by affecting the corneal host epithelium only.
Therefore, the preliminary observation, mentioned by the authors in this letter, that cryopreserved amniotic membrane can be infected with herpes simplex virus 1 is a findings of particular interest that should be taken into account when using amniotic membrane in eyes with a history of herpetic epithelial disease. However, it is worth reminding readers that in case of immune-mediated keratitis, where corneal damage, ulceration, and subsequent loss of transparency is related to sterile inflammation, such as herpes necrotizing stromal keratitis, multilayer amniotic membrane transplantation in conjunction with antiviral and corticosteroid therapy seemed effective in treating and improving the outcomes of stromal herpetic disease.