Wolfgang Wetzel

Initial clinical experience with the trabecular micro-bypass stent in patients with glaucoma

This study was undertaken to evaluate the efficiency of a trabecular micro-bypass stent designed to allow direct aqueous drainage from the anterior chamber into Schlemm’s canal in patients with glaucoma. In this prospective case series of 6 patients with open-angle glaucoma, the microstent was inserted ab interno under local anesthesia in an ophthalmic operating room. Patients were seen postoperatively at 1 to 2 d, 1 wk, and 1, 2, 6, and 12 mo. All stents were successfully placed within Schlemm’s canal. Mean intraocular pressure (IOP) at preoperative baseline was 20.2±6.3 mm Hg (range, 14–31 mm Hg). Mean IOP decreased during the immediate postoperative period to approximately 12 to 13 mm Hg and was stabilized at 14 to 15 mm Hg with reduction of medication throughout 1 y of follow-up. No major complications occurred. According to observations reported in this feasibility study, the microstent was effective in reducing IOP and in decreasing the number of glaucoma medications required to control IOP. Implantation procedures were safe, and stents remained in place throughout the follow-up period. None of the complications traditionally associated with filtering surgery were reported. Further research on this stent in a larger group of patients is needed to assess its role in glaucoma therapy.

Mitomycin-C in Laser Sclerostomy: Benefit and Complications

BACKGROUND AND OBJECTIVE The authors studied the effect of topical mitomycin-C administration on the maintenance of filter function and intraocular pressure (IOP) following laser sclerostomy. PATIENTS AND METHODS Twenty-six patients with a presumed high risk of episcleral scarring were treated intraoperatively with topical mitomycin-C (0.5 mg/ml) for 3 to 5 minutes. Their IOPs were monitored for at least 2 years. The IOP data of these patients were compared with the results for 46 patients who underwent the identical procedure without antimetabolite. RESULTS IOPs below 23 mm Hg were achieved in 70% of the mitomycin-C-treated patients. Compared with the non-mitomycin-C group, the rate and duration of early postoperative hypotony was significantly increased in the mitomycin-C-treated group. CONCLUSION Mitomycin-C is useful for maintaining successful filter function in patients with unfavorable prognoses. However, severe and persistent hypotony may occur.

Comparison of the efficacy of ER-YAG laser sclerostomy ab externo versus trabeculectomy in the treatment of patients with primary open – angle glaucoma

SummaryPurpose: This study was conducted to compare the efficacy of the Er-YAG laser sclerostomy ab externo versus trabeculectomy in the treatment of primary open – angle glaucoma. Methods: Twelve patients with POAG underwent ab externo laser sclerostomy using an Er-YAG laser (Sklerostom 2.9®; λ = 2940 nm, t = 200 μs, 2 Hz, 400 μm, 15 mJ). Only local medication was used, and there were no risk factors for failure. As a control group 12 patients out of 248 standardized trabeculectomies were matched in terms of age, sex, diagnosis and local medications. No antimetabolites were used in either group. Results: After a follow-up of 9 months in the sclerostomy group 53 %; (7/12; P = 0.03) showed a patent fistula in comparison of 100 % in the trabeculectomy group. There was a significantly lower mean IOP during the first postsurgical week in the group of sclerostomies (3.6 ± 1.5 mmHg versus 7.5 ± 2.7 mmHg; P = 0.0001) with a higher incidence of choroidal detachments (9/12 versus 2/12; P = 0.004). The choroidal detachments lasted longer in the sclerostomy group (3.5 months versus 0.3 months; P = 0.014). Iris incarcerations were found only in sclerostomies (7/12; P = 0.05). Conclusions: Based on these findings, Er-YAG laser sclerostomy prooved to be less effective than trabeculectomy in the treatment of glaucoma patients. Er-YAG laser sclerostomies were associated with a higher incidence of postsurgical complications such as hypotony, choroidal detachments and iris incarcerations. At this point Er-YAG laser sclerostomy is not superior to conventional trabeculectomy.ZusammenfassungFragestellung: Die ab externo-Erbium-YAG-Lasersklerostomie wurde in der Hoffnung entwickelt, eine einfache, schnelle, fistulierende Glaukomtherapie mit geringer Vernarbungsrate zur Verfügung zu haben. Die vorliegende Studie vergleicht die ab externo-Erbium-YAG-Lasersklerostomie mit der konventionellen Trabekulektomie, um der Frage nachzugehen, ob Erfolgs- und Komplikationsraten beider Verfahren vergleichbar sind. Patienten und Methode: Es wurden 12 Patienten mit primärem Offenwinkelglaukom mit geringem Vernarbungsrisiko, bei denen eine ab externo-Lasersklerostomie durchgeführt worden war, in die Studie eingeschlossen. Diesem Kollektiv wurden 12 Patienten einer Kontrollgruppe, die mit einer standardisierten Trabekulektomie versorgt worden waren gegenübergestellt. Das Matchverfahren beinhaltete Alter, Geschlecht und Anzahl der Glaukommedikation vor dem Eingriff. Antimetaboliten wurden in beiden Gruppen nicht verwandt. Ergebnisse: Nach 9 Monaten waren in der Gruppe der Sklerostomien 53 % der Fistelkanäle durchgängig, während in der Gruppe der konventionellen Filtrationschirurgie 100 % der Fisteln offen geblieben waren (p = 0,03). Als Komplikation fand sich in der ersten postoperativen Woche in der Sklerostomiegruppe eine ausgeprägtere Hypotoniephase (3,6 ± 1,5 mmHg versus 7,5 ± 2,7 mmHg; p = 0,001). Diese Hypertoniephase korrelierte mit häufigeren (9/12 versus 2/12; p = 0,004) und länger anhaltenden (3,5 Monate versus 0,3 Monate; p = 0,014) chorioidalen Abhebungen. Irisinkarzerationen fanden sich nur in der Gruppe der Sklerostomien (7/12; p = 0,05). Schlußfolgerung: Die Studie zeigt eine geringere Erfolgsrate in der Behandlung von Glaukompatienten mit geringem Vernarbungsrisiko bei Verwendung der Erbium-YAG-Lasersklerostomie im Vergleich zur konventionellen Trabekulektomie. Bei der Erbium-YAG-Lasersklerostomie waren Komplikationen wie postoperative Hypertonie, chorioidale Abhebungen und Irisinkarzerationen häufiger. Damit stellt die Erbium-YAG-Lasersklerostomie derzeit keine Alternative zur konventionellen Trabekulektomie dar.

Laser sclerostomy ab externo with the Erbium:YAG laser using a new flexible application system

A fistula from the anterior chamber of the eye into the subconjunctival space can be created by laser application ab externo (laser sclerostomy). The success of the procedure mainly depends on the special application system. The pulsed Erbium-YAG laser (2940 nm) was used as the energy source. The laser energy was guided to the application system via a ZrFl fiber with low attenuation at this wavelength. Because this fiber cannot be used in direct contact to the sclera, an optical coupling unit transmitted the energy to a short quartz fiber. This fiber was inserted in a specially sharpened retractable cannula to guide it into the subconjunctival space. Then the laser energy could be applied directly to the sclera to form the fistula. The procedure was demonstrated in vivo using rabbit eyes. A working fistula with formation of a filtering bleb could be achieved. The trauma to the conjunctiva was as minimal as in a subconjunctival injection. The minor alteration of the conjunctiva in this procedure compared to traditional surgical methods like goniotrepanation or trabeculectomy may cause less scarification and therefore less failure.