From the Guidelines
Angle-based glaucoma surgeries are minimally invasive procedures that target the eye's drainage system to reduce intraocular pressure in patients with glaucoma, and they include techniques such as trabecular micro-bypass stents, goniotomy, trabeculotomy, and canaloplasty. These surgeries specifically focus on the trabecular meshwork and Schlemm's canal in the anterior chamber angle, which is the primary site of outflow resistance in open-angle glaucoma 1. Common angle-based procedures either bypass, remove, or modify the trabecular meshwork to enhance the natural drainage pathway of aqueous humor. The procedures are typically performed through small corneal incisions, often in conjunction with cataract surgery, and require specialized microscopes with gonioscopic visualization to access the drainage angle. Some key points to consider when evaluating angle-based glaucoma surgeries include:
- The effectiveness of these surgeries in reducing intraocular pressure and slowing the progression of glaucoma, as demonstrated by studies such as the one published in Ophthalmology in 2016 1
- The potential benefits of angle-based procedures, including quicker recovery times and fewer complications compared to traditional glaucoma surgeries like trabeculectomy
- The suitability of angle-based procedures for patients with mild to moderate glaucoma who need modest pressure lowering or want to reduce medication burden
- The importance of considering the individual patient's needs and medical history when selecting a surgical approach, as highlighted by studies such as the Tube Versus Trabeculectomy (TVT) Study 1. Overall, angle-based glaucoma surgeries offer a promising treatment option for patients with glaucoma, and they should be considered as part of a comprehensive treatment plan.
From the Research
Angle-Based Glaucoma Surgeries
Angle-based glaucoma surgeries are a type of minimally invasive glaucoma surgery (MIGS) that aims to reduce intraocular pressure (IOP) by increasing trabecular outflow. Some of the current approaches include:
- Increasing trabecular outflow (Trabectome, iStent, Hydrus stent, gonioscopy-assisted transluminal trabeculotomy, excimer laser trabeculotomy) 2
- Suprachoroidal shunts (Cypass micro-stent) 2
- Reducing aqueous production (endocyclophotocoagulation) 2
- Subconjunctival filtration (XEN gel stent) 2
Effectiveness of Angle-Based Surgeries
Studies have shown that angle-based MIGS can be effective in reducing IOP, with some procedures being more effective than others. For example, trabeculectomy has been shown to be more effective in reducing IOP compared to transscleral cyclophotocoagulation 3. Additionally, angle-based MIGS has been shown to be effective in reducing IOP with and without prior laser trabeculoplasty, although prior laser trabeculoplasty may be associated with a higher chance of subsequent glaucoma surgery 4.
Comparison of Treatments
Comparative effectiveness studies have shown that medical, laser, and surgical treatments can decrease IOP and reduce the risk of optic nerve damage and visual field loss 5. However, the direct effect of treatments on visual impairment and the comparative efficacy of different treatments are not clear. Laser therapy, such as laser goniotherapy, has also been shown to be a beneficial mode of therapy for open angle glaucoma, although longer follow-up is needed to define its role in secondary and aphakic glaucomas 6.