Baylor College. US: While using eye drops to treat eye injuries may seem like a simple
enough task, doing so multiple times per day can cause side effects such
as irritation and toxicity from high drug concentrations, and poor
patient compliance is also an issue. In response to this, researchers at
Baylor College of Medicine have developed a nanowafer drug delivery
system, in which there is a slow drug release from a nanowafer, or a
small transparent disc placed on the surface of the eye that contains
arrays of drug-loaded nanoreservoirs.
In their latest study published in ACS Nano,
researchers found that in mice, the nanowafer drug delivery system was
more effective in treating corneal neovascularization, which results in
severe corneal clouding and blood vessel ingrowth, than a topical eye
drop therapy.
“Eye drops are very inefficient because they are diluted out by the
tears and then rapidly washed away from the eye so there’s very little
time for the medication in the drop to be picked up or absorbed by the
tissue, and as a consequence the concentration of it doesn’t achieve a
high level,” said Dr. Stephen C. Pflugfelder, professor of ophthalmology
at Baylor and an author on the paper.
Dr. Ghanashyam Acharya, assistant professor of ophthalmology at
Baylor and senior author of the paper, developed the wafer technology
that can be placed on the surface of the eye. It slowly dissolves and
maintains a high concentration of the drug in the tear film and loads up
the tissue to provide better efficacy.
Using an animal model, researchers sought to determine whether using
the wafer technology would deliver medication more consistently to the
eye when treating corneal neovascularization, which can be blinding.
“We found that the nanowafer was much more efficient compared to eye
drop treatment. For example, once a day nanowafer treatment has almost
twice the efficacy compared to delivering eye drops two times a day,”
said Acharya.
“It’s very novel. In this study, not only did it demonstrate the
efficacy in delivering these drugs that inhibit the corneal blood
vessels but it also demonstrated the efficacy and feasibility of the
wafer drug delivery system,” said Pflugfelder. “This would greatly
revolutionize treatment of severe infections of the cornea that require
treatment with eye drops every hour for 24 hours a day for days and
weeks on end. It could deliver more antibiotic to the cornea and it
could theoretically be done once a day.”
Researchers are now working on increasing the drug release from the
nanowafer from once a day to one to two weeks. Also, because the
technology does not require refrigeration, it would be very useful in
treating eye infections and injuries in developing countries.
Others who took part in the study include Daniela C. Marcano, Crystal
S. Shin, Xiaoyoung Yuan, Xia Hua and Lucas Isenhart of Baylor College
of Medicine.
This work was supported by a grant from the Department of Defense (Award No. 1W81XWH-13-1-0146).