Internal sclerostomy using laser ablation of dyed sclera in glaucoma patients: a pilot study

Twelve eyes of 12 patients with refractory glaucoma were treated with internal sclerostomy using laser ablation of dyed sclera. The technique involves iontophoretic impregnation of the sclera at the limbal region with 1% methylene blue and subsequent delivery of a pulsed dye laser beam to the stained area through a goniolens. The red wavelength of 664 nm generated by the laser is maximally absorbed by the stained sclera and creates a through and through sclerostomy. Successful complete sclerostomy was achieved in seven eyes (58.3%) but there was some reduction of intraocular pressure (IOP) in all cases. Mean prelaser IOP (of all 12 eyes) was 36.6 mm Hg and 1 hour after therapy it was reduced to 20.0 mm Hg. At the end of the follow-up period (mean 16 months) the mean IOP was 23.7 mm Hg; five eyes (41%) maintained their IOP below 22 mm Hg, and the average number of medications per eye came down from 3.25 to 2.25 per eye. Transient corneal burns with Descemet's membrane folds adjacent to the laser impact zone were detected in eight eyes (67%). No major complications like IOP spike, hyphaema, iridodialysis, or retinal detachment have been detected. Clear cornea and dark blue scleral staining are essential for the mechanical success of this procedure. Gonioscopic laser internal sclerostomy of methylene blue dyed sclera is technically feasible and the preliminary results of IOP control in refractory glaucoma are promising. Modifications of the iontophoresis process and laser parameters are currently under investigation in order to improve these results.