Photodynamic biologic tissue glue.

We studied both heat- and light-activated tissue glues, and while a heat-activated mixture such as albumin and fluorescein isothiocyanate was effective, we believed that a light-activated substance would have less of an effect on adjacent tissue. Our glue uses a photosensitive singlet oxygen generator to cross-link a protein solder with corneal stromal collagen. The mixture consists of 18% fibrinogen and 2.6 mg/ml of riboflavin-5-phosphate activated with a blue-green (488-514 nm) Argon laser. We tested our glue by soldering 5-mm penetrating central corneal incisions made in human cadaver eyes. The strength of the closure was measured by cannulating the vitreous cavity with an 18-gauge needle connected to a saline reservoir. The pressure in the reservoir was elevated by connecting it to a sphygmomanometer. Immediately following tissue closure, the intraocular pressure was increased until the wound burst. We soldered and measured 10 eyes and found a mean bursting pressure of 154 mm Hg, with a range of 80-260 mm Hg. Our laser-activated tissue glue is an effective adhesive for corneal tissue, and we now plan to carry out toxicity studies in living animals.