Robotic laser tissue welding of sclera using chitosan films.
OBJECTIVE
To demonstrate the feasibility of scleral wound closure using a novel adhesive made of chitosan film.


METHODS
Five-millimeter scleral lacerations were created in enucleated pig eyes. Casted chitosan films were sized to 7x7 mm patches. Lacerations were sealed with chitosan film alone (7 eyes) or chitosan film followed by laser irradiation using a near infrared laser (1,455 nm) at 350 mW for 6 minutes (7 eyes). Seven eyes were closed with 9-0 nylon suture for comparison (7 eyes). Outcome measures included watertight closure, closure time, and leak pressure. Leak pressure was measured with a pressure transducer attached to tubing continuously monitored intraocular pressure during saline infusion. Watertight closure testing was performed immediately following closure (n = 3 per group) and after 24 hours (n = 3 per group). One eye in each group was fixed in formalin for histology.


RESULTS
All wounds were watertight for each closure method. Mean closure time with unlasered chitosan film was 2.24 minutes (range 1.80-3.26, 7 eyes) with a mean leak pressure of 303 mm Hg (range 217-364, 3 eyes). Mean closure time with lasered chitosan was 12.47 minutes (range 11.45-14.15, 7 eyes) with a mean leak pressure of 454.7 mm Hg (range 152-721, 3 eyes). Suture closure required a mean of 4.83 minutes (range 4.03-7.30, 7 eyes) and resulted in a mean leak pressure of 570.3 mm Hg (range 460-646, 3 eyes). Both lasered and unlasered chitosan eyes remained watertight after 24 hours. Histology revealed minimal laser tissue damage in lasered eyes.


CONCLUSIONS
In this preliminary study chitosan film successfully closed scleral lacerations with and without the application of laser energy. While laser appears to strengthen the closure, it significantly increases the closure time. Chitosan based adhesives hold promise as a scleral wound closure technique.
Garcia
Pablo
P
SRI International, Menlo Park, California, USA.
Mines
Michael J
MJ
Bower
Kraig S
KS
Hill
J
J
Menon
J
J
Tremblay
Eric
E
Smith
Benjamin
B
D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D048271:Chitosan / Q000627:therapeutic use*; D022125:Lacerations / Q000628:therapy*; D053685:Laser Therapy; D009924:Organ Culture Techniques; D012371:Robotics; D012590:Sclera / Q000293:injuries*; D013536:Suture Techniques; D013552:Swine; D014014:Tissue Adhesives / Q000627:therapeutic use
D001672:Biocompatible Materials; D014014:Tissue Adhesives; D048271:Chitosan