Kenneth R. Kenyon
An innovative product based on lyophilized human amniotic membrane
allows topical application to the ocular surface of unlimited quantities of
amniotic membrane biological factors.
According to the preliminary results of an ongoing European study, the
product is safe and stimulates healing of persistent defects of the corneal
In other words, it accomplishes what amniotic membrane grafting
does, but in an easier, painless, cheaper and patient-friendly way, without the
need for surgery, Kenneth R. Kenyon, MD, said in an interview with
Ocular Surgery News.
Development and study
Five years ago, Emiliano Ghinelli, MD, began the development of amniotic
membrane extract (AMX). AMX is currently produced under license from Keera in
collaboration with the Veneto Tissue Bank in Italy. It is not yet commercially
available but is undergoing evaluation in a multicenter clinical trial.
The immediate clinical application of AMX has been to promote
wound healing of persistent corneal epithelial defects occurring as serious
complications of several corneal conditions, most commonly herpes simplex or
zoster, trigeminal nerve defect, or diabetes, Dr. Kenyon, OSN U.S.
Edition Cornea/External Disease Section Editor Emeritus, said.
Herpes simplex keratitis with corneal
ulceration, inflammation and neovascularization resolved after AMX
Persistent corneal epithelial defect due to
acoustic neuroma healed by AMX therapy.
Images: Kenyon KR
Approximately 50 patients have been enrolled in the trial, and the final
outcome analysis should be available within the next 2 months. Preliminary
indications suggest that there are no safety concerns and that corneal wound
healing has improved in the majority of cases. The therapeutic efficacy of AMX
appears to be comparable to, or perhaps better than, that of amniotic membrane
graft, but further data are needed.
Preliminary study results were presented at the International Symposium
on Ocular Pharmacology and Therapeutics meeting in Rome in December.
The AMX preparation is in the form of a lyophilized powder, which
requires the addition of saline for reconstitution as an eye drop. As it is
non-preserved, it must be retained in normal refrigeration for no longer than
An advantage of AMX is that it can be applied topically as an eye drop
at a frequency determined by the severity of the condition, typically
beginning hourly and then rapidly decreasing, Dr. Kenyon explained.
Besides not requiring the time, effort and expense of a surgical
procedure, the lyophilized product overcomes the limitations of amniotic
membrane grafts, which can only be effective for as long as their content of
growth factors and other bioactive factors remains viable.
With AMX, we can continue to provide the wound healing factors
directly and continuously, at the site where they are needed and for as long as
they are needed, Dr. Kenyon said.
From the point of view of the patient, being treated by off-the-shelf
topical medications rather than surgery holds obvious advantages.
Compliance is better, quality of life is better, and patients are
more relaxed, he noted.
Dr. Kenyon said that, besides the indications that are currently
investigated in the study, AMX has many other potential ocular and possibly
This product may perhaps be useful following refractive surgery,
in severe dry eye, and in various other ocular surface disorders, he
said. by Michela Cimberle
- Kenneth R. Kenyon, MD, can be reached at Eye Health Vision Centers,
51 State Road, Dartmouth, MA 02747, U.S.A., or Cornea Consultants
International, Tal 13, 80331, Munich, Germany; +1-508-994-1400; fax:
+1-508-992-7701; e-mail: firstname.lastname@example.org. Dr. Kenyon and Dr.
Ghinelli have a financial interest in the development of amniotic membrane
extract through Keera.