From the Guidelines
Angle-based glaucoma surgeries are primarily indicated for patients with open-angle glaucoma who have inadequate intraocular pressure (IOP) control despite maximum tolerated medical therapy or who experience medication side effects or compliance issues, with expected outcomes including IOP reduction of 20-40% from baseline, decreased dependence on glaucoma medications, and stabilization of visual field loss, as supported by the most recent study 1.
Indications for Angle-Based Glaucoma Surgery
The indications for angle-based glaucoma surgery include:
- Inadequate IOP control despite maximum tolerated medical therapy
- Medication side effects or compliance issues
- Patients with mild to moderate glaucoma
- Those undergoing cataract surgery
- Younger patients who might need multiple interventions throughout their lifetime These procedures target the eye's natural drainage system to enhance aqueous outflow, and are typically less invasive than traditional filtering procedures like trabeculectomy, offering quicker recovery times and fewer serious complications 1.
Expected Outcomes
The expected outcomes of angle-based glaucoma surgery include:
- IOP reduction of 20-40% from baseline
- Decreased dependence on glaucoma medications (often reducing the medication burden by 1-2 medications)
- Stabilization of visual field loss
- Quicker recovery times and fewer serious complications compared to traditional filtering procedures like trabeculectomy The procedures work by bypassing or removing the diseased trabecular meshwork, which is the primary site of outflow resistance in open-angle glaucoma, allowing aqueous humor to flow more freely into Schlemm's canal and collector channels 1.
Postoperative Care
Postoperatively, patients typically require:
- Anti-inflammatory drops (prednisolone acetate 1% four times daily for 1-2 weeks, then tapered)
- Antibiotic drops (moxifloxacin 0.5% four times daily for 1 week)
- Close monitoring of IOP during the first few weeks It is essential to note that the IOP-lowering effect of angle-based glaucoma surgery may be more modest and potentially less durable over time, and patients should be closely monitored for any changes in their condition 1.
From the Research
Indications for Angle-Based Glaucoma Surgery
- The primary indication for angle-based glaucoma surgery is uncontrolled intraocular pressure (IOP) despite maximum medical therapy 2, 3, 4.
- Patients with primary open-angle glaucoma, capsular glaucoma, or glaucoma after penetrating keratoplasty may benefit from angle-based glaucoma surgery 3, 4.
- The decision to operate is often based on the level of IOP, the presence of visual field defects, and the clinical observation of the optic nerve head 5.
Expected Outcomes of Angle-Based Glaucoma Surgery
- The primary outcome of angle-based glaucoma surgery is a reduction in IOP, with a target pressure of less than 18 mmHg, 15 mmHg, or 12 mmHg, depending on the specific criteria used 2, 3.
- Successful surgery can result in a significant reduction in IOP, with mean IOP decreasing from 19.3 mmHg to 8.4 mmHg at 5 years after trabeculectomy 2.
- The cumulative success rate for angle-based glaucoma surgery can range from 49.1% to 73.2%, depending on the specific criteria used and the length of follow-up 2, 3.
- Complications of angle-based glaucoma surgery can include hypotony maculopathy, shallow anterior chamber, and choroidal detachment, but these can be minimized with proper surgical technique and postoperative care 2, 6.
Comparison of Surgical Techniques
- Different surgical techniques, such as trabeculectomy, glaucoma drainage device implantation, and laser neodymium:YAG cyclophotocoagulation, can be used to manage intractable glaucoma after penetrating keratoplasty 4.
- The choice of surgical technique may depend on the specific clinical situation, including the level of IOP, the presence of visual field defects, and the patient's overall health status 4.
- No significant differences were found in the proportion of patients who developed postoperative IOP above 20 mmHg, hypotony, or graft failure among the three surgical techniques 4.