Comparative Efficacy of the SLT versus LASAG Nd: YAG Delivery Systems in Rabbits.

PURPOSE: The efficacy of two types of contact transscleral Nd:YAG laser delivery systems, a synthetic sapphire-tipped laser probe connected to a Surgical Laser Technologies (SLT) laser and a quartz fiberoptic tip connected to a LASAG Microrupter III, was compared. METHOD: A total of nine pigmented rabbits underwent transscleral LASAG cycloablation in one eye (3.2 W, 0.5 s); an additional eight rabbits underwent Surgical Laser Technologies cycloablation (3.0 W, 0.5 s). RESULTS: The maximum difference in intraocular pressure between the experimental versus fellow eyes was - 15.09 mm Hg (+/-0.25) with the LASAG and -13.16 mm Hg (+/-3.12) with the SLT laser; in both delivery systems, this difference was achieved 4 days postoperatively. The differences between the two groups in duration of pressure reduction was not statistically significant (p = 0.83). CONCLUSION: These data suggest that these delivery systems are equally effective in lowering intraocular pressure in rabbits. Histological changes of the ciliary processes and adjacent ocular tissue are presented.

Ab-interno sclerostomy using a goniodiathermy instrument.

We describe the use of a new instrument designed to create a simultaneous goniopuncture with diathermy using an ab-interno technique. The goniodiathermy ab-interno procedure was first performed on three eyes of three cynomolgus monkeys. Intraocular pressure (IOP) assessment and histologic examination were performed over a 10-day period. A functioning filtration bleb with a patent sclerostomy was achieved in all of the experimental eyes. A pilot study involving four eyes of four glaucoma patients also was performed. Of these four, successful long-term functioning filtration areas with adequate lowering of IOP were achieved in only two. The remaining two required further surgical intervention. Although combining goniopuncture and diathermy into a one-step ab-interno procedure proved successful in the primates studied, the preliminary use of this new instrument as a method of creating a filter in humans raises questions regarding its clinical usefulness.

Adjunctive use of transconjunctival mitomycin-C in ab externo diode laser sclerostomy surgery in rabbits.

This study evaluates the role of transconjunctival mitomycin-C (MMC) in laser sclerostomy surgery. Sixteen albino rabbits underwent ab externo diode laser sclerostomy surgery in one eye (with the fellow eye as a control), with a single, intraoperative, 7-minute transconjunctival application of MMC (MMC group). Ten rabbits had the same sclerostomy surgery without MMC (NOMMC group). Successful filtration, defined as a difference in intraocular pressure less than 4 mm Hg between the operative and control eyes, lasted significantly longer in the MMC group (16.4 +/- 11.0 days) than in the NOMMC group (8.5 +/- 4.5 days) (P = .02). These data suggest that transconjunctival MMC can enhance the success of diode laser sclerostomy surgery in rabbits.

Effects of papaverine pilocarpine and epinephrine on fistulized rabbit conjunctiva.

SUMMARY: Pretreatment with pilocarpine hydrochloride has been demonstrated to increase the number of myofibroblasts in fistulized conjunctiva in rabbits. To determine if this observation is related to changes in the conjunctival vasculature that may be linked to pilocarpine, we evaluated the effects of a vasodilator and a vasoconstrictor in comparison with pilocarpine hydrochloride. Twenty Dutch-belted rabbits, with five rabbits per group, were treated in a masked fashion in both eyes with topical solutions of 4% pilocarpine hydrochloride, 0.3% papaverine, a combination of 4% pilocarpine and 2% epinephrine, or artificial tears for 3 months. Four of five rabbits in each group underwent thermal sclerostomies in both eyes; the fifth rabbit in each group served as a nonsurgical control. The mean number of myofibroblasts per high-power field was greater in the surgical eyes treated with pilocarpine (6.35 $pM 0.48) or papaverine (9.22 $pM 0.44) than in the eyes treated with both epinephrine and pilocarpine (4.80 $pM 0.70) or artificial tears (5.20 $pM 0.40). These results suggest that the vasoactive properties of topical agents can increase or limit the number of myofibroblasts following filtration surgery.