A glaucoma drainage valve more effectively lowers intraocular pressure (IOP) than a laser procedure, according to findings published in International Ophthalmology. The study shows that transscleral cyclophotocoagulation can effectively reduce IOP in eyes with advanced glaucoma, but that the implant more efficiently decreases both IOP and the number of antiglaucoma agents necessary.

The prospective observational clinical study examined 30 eyes of 30 patients with advanced open-angle glaucoma. The patients were randomized for either a laser procedure or Ahmed valve implantation to manage their IOP. The study sample consisted of 12 males and 18 females with a mean age of approximately 75.8 years. Inclusion criteria included a diagnosis of advanced primary open-angle glaucoma, IOP greater than 21 mm Hg, cup-to-disc ratio 0.9 to 1.0, failure to meet the target IOP with either maximal tolerated local medical therapy (2 to 4 antiglaucoma agents) or systemic therapy. A total of 15 eyes were put into group A and were treated with the laser procedure. The other 15 eyes (group B) were implanted with Ahmed valves. The follow-up time of the study was 12 months. Absolute success was defined as achieving an IOP between 6 mm Hg and 15 mm Hg and at least 30% reduction of the IOP from baseline under reduced or the same number of antiglaucoma agents after the surgical procedure without following glaucoma surgeries. Qualified success was achieving IOP between 6 mm Hg and 18 mm Hg and at least 20% reduction of the IOP from baseline regardless of the number of postoperative antiglaucoma agents.

Investigators saw a 30% (or greater) reduction in IOP in 33.3% of eyes in group A, the laser procedure group, and in 73.3% of eyes in group B, the Ahmed valve group, during the follow-up period of 12 months. A statistically significant decrease in the number of eye drops was observed in both groups (P <.01). Of note, 53.3% of the eyes of group A underwent additional antiglaucoma procedures to achieve target IOP. The number of the local medications that were administered 12 months after the ocular surgery was 2 (± 1.3) in group A and 0.57 (± 0.9) in group B, compared with 3.2 (± 0.78) in group A and 3.33 (± 0.7) in group B administered before surgery (P =.016). Additionally, 8 eyes (53.33%) in group A were referred for additional treatment due to an acute postoperative rise in IOP. No further anti-glaucoma procedures were necessary for group B.


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 The research concludes that patients with severe glaucoma were more effectively treated with Ahmed valves in the 12-month follow-up period than the laser procedure.

Researchers note several limitations of their study, including its limited sample size and relatively short follow-up duration. Additionally, researchers note that their results are not applicable to community-based glaucoma practices since the participants in the current study had advanced glaucoma and multiple ocular comorbidities. 

Reference

Fili S, Kontopoulou K, Vastardis I, et al. Transscleral cyclophotocoagulation with MicroPulse® laser versus Ahmed valve implantation in patients with advanced primary open-angle glaucoma. Int Ophthalmol. Published online January 3, 2021. doi:10.1007/s10792-020-01682-0