Sutureless surgery advances with help of corneal
WASHINGTON, DC - A new class of tissue adhesives known as biodendrimers
may reduce or eliminate the need for sutures in most types of corneal
surgery, reported US researcher Terry Kim MD at a Research to Prevent
Blindness Foundation seminar.
The new glue shows promise for the repair of traumatic corneal wounds,
surgical incisions from cataract surgery and corneal transplantation,
and even LASIK surgery.
compounds avoid the disadvantages of sutures, such as trauma to
the cornea, uneven healing and astigmatism, infection, inflammation
and scarring, Dr Kim said.
Developed by Duke University chemist Mark Grinstaff PhD, biodendrimers
are made of a central core of polymer which branches radially outwards.
Biocompatible and biodegradable, the glue should not cause toxicity
within the eye. Unlike alkyl-cyanoacrylate, the conventional 'super
glue', which hardens as soon as it comes out of the tube, the biodendrimer
does not begin to polymerise or harden until activated by an argon
"You can apply this novel adhesive with much more control and
ease than with conventional cyanoacrylate adhesives.
"In addition, you can control its polymerisation with an argon
laser beam or other light source, giving it a major advantage over
cyanoacrylate glue which polymerizes immediately upon contact with
water or a moist surface," Dr Kim told EuroTimes.
Biodendrimers are easy to apply using a spatula to spread them over
the wound. Another way of applying the glue is by putting it into
a syringe and injecting it - a method Dr Kim expects will be adopted
in future clinical trials.
That method allows precise delivery and is easy to control. This
will be particularly useful for cataract surgery or corneal transplant
incisions, or with LASIK flaps, where the surgeon can see the wound
"That is what is nice about the cornea. It's right up front.
We see the wound and the incision. It's very clearly visible and
since the cornea is very accessible, we can get to it without complication
and know where to put it exactly. For other areas of the eye, it
may be a little more difficult," Dr Kim said.
Putting the glue in the wrong place would not be much of a problem
because when it hardens it takes on a very smooth rubbery texture
and remains in one piece.
If it is accidentally delivered into the anterior chamber of the
eye, for example, the eye should degrade the glue with hopefully
none or minimal inflammatory or toxic reaction.
It can also be removed by pulling it off in one piece after it hardens
and should not pull the tissue along with it, he said.
The Duke University team initially tested the glue with enucleated
human eyes obtained from an eye bank. The glue performed well in
full-thickness and lamellar corneal wound models with no evident
problems with wound sealing.
It successfully sealed linear and stellate corneal incisions as
well as sutures. It also successfully sealed LASIK flaps.
Dr Kim expects to glean more information when he begins testing
biodendrimers in an in vivo model.
He has chosen the chicken eye model because its cornea is very similar
to the human cornea, with much of the same proteins and same corneal
The in vivo testing should determine how this glue reacts with the
surrounding tissue, how long the glue lasts, whether it causes toxicity
or problems with inflammation, and how strong it works in the chicken
eye. Clinical trials may begin in as little as two years.
"This is an entirely new technology for adhesives to replace
sutures in ocular surgery which, for the first time, looks feasible
and appears as though it will be compatible with the tissue. It
should be easily applied in the operating room setting.
"The weakness is that he is just now beginning to apply it
to a living animal model. So we'll have to reserve judgment. But
overall, the work is extremely promising and it is the first time
I have seen a new adhesive that actually looks as if it is going
to be useful in the future," H. Dwight Cavanagh MD, PhD commented.
Fibrinogen tissue adhesives are also under study but they require
the isolation of autologous fibrinogen, making them impractical
in an emergency procedure. Moreover, the risk of infection rules
out the use of donor fibrinogens, Dr Kim added.