Intrastromal holmium laser keratostomy: long-term results

A new filtering procedure, the Intrastromal Holmium Laser Keratostomy (ILK) has been developed. A laser canal is created intrastromally in the cornea anterior to Schwalbe's line in the floor of a corneo-scleral tunnel incision made with a knife from the corneal site. Theoretically, the complications of the conventional Subconjunctival Holmium Laser Sclerostomy (SLS) can thus be avoided. Experimental and clinical evaluation of the new procedure, as well as clinical long-term results are presented.

The ILK was evaluated experimentally on bank eyes and clinically using postoperative Ultrasound Biomicroscopy (UBM). The clinical long-term effect was evaluated by a follow-up of the first 22 ILK performed on 17 eyes in 17 consecutive patients with complicated, refractory primary and secondary open angle glaucoma. Preoperative subconjunctival mitomycin-C injection (0.02 mL of 0.2 mg/mL) was used.

The experimental and clinical evaluations show that the collateral thermal tissue coagulation made by the Holmium laser in ILK probably is an advantage, because the subsequent shrinkage prevents postoperative self sealing of the laser canal. Complete surgical success without medication and reoperations was reached in 63% of the eyes with a mean observation time of 22.5 months (range: 16.6-26.7 mos.). Any failure appeared within the first 10 months. Only 13% of the eyes had early iris incarcerations, there were no late incarcerations. Twenty-five percent had temporary shallow anterior chambers.

The mitomycin-ILK procedure has shown obvious better results than the conventional SLS technique due to a considerable reduction in postoperative complications. Since the present material further developments in the ILK technique has made this procedure still more attractive.