F. Kuhne

Noncontact laser penetrating keratoplasty: in-vivo comparative evaluation in rabbit and cat

With their inherent precision and avoidance of tissue deformation, non-contact laser trephines may minimize graft postoperative astigmatism. Laser-cut corneal button geometry surpassed handheld and equaled Hanna and Krumeich vacuum held trephines, without significant endothelium or wound healing differences for linear cuts between laser and metal blades. To compare the laser with metal trephines, we performed 8 mm diameter grafts on 12 rabbits and 12 cats. A new laser system, using an advanced pulsed HF laser coupled to a computer controlled optical delivery system and equipped for quasi-instantaneous simultaneous 8-point corneal marking (200 ns) for precise suture placement at the 5.5 to 10.5 mm diameter and rapid corneal trephination (approximately equals 6 sec), or a new disposable sterile vacuum-assisted Hessburg-Barron (HB) trephine was used in each procedure. Circumferential keratotomies were more accurately and more easily performed with the laser. No statistical differences were found in wound strength and healing. The laser produced a slightly lower astigmatism. These initial results suggest the safety of HF laser corneal marking-trephination and its potential for PK procedures in humans.

Laser sclerectomy and 5-FU controlled-drug-release biodegradable implant for glaucoma therapy

Laser sclerectomy, a simple filtering procedure performed to alleviate high intraocular pressure in glaucoma patients, was taught to offer longer lasting effect and therefore improve the patients outcome when compared with the standard trabeculectomy procedure. Recent clinical trials have shown that this was not the case and pharmacologic wound healing modulation is also required with this new procedure. Five-Fluorouracil (5-FU) is useful as an adjunct treatment for glaucoma filtering surgery. However, efficacy depends upon maintaining sustained drug levels, currently achieved by repeated daily injection of the drug for several weeks. To overcome this limitation, we designed a biodegradable implant for the sustained release of 5-FU. After laser sclerectomy, the implant is inserted through the same 1 mm wide conjunctival snip incision and positioned below the open channel. Implantation takes less than a minute. The implant releases the drug for over 15 days and totally biodegrades in less than 100 days. The combined laser surgery and implantation procedure show great potentials for the treatment of glaucoma.