What is the role of goniotomy without goniopuncture in treating glaucoma?

Goniotomy Without Goniopuncture in Glaucoma Management

Goniotomy is an effective standalone surgical procedure for treating various forms of glaucoma, particularly when trabecular meshwork dysfunction is the primary pathology, and does not require goniopuncture (which is not a standard component of the procedure).

Understanding the Procedure

Goniotomy is a distinct surgical technique that involves creating an incision in the trabecular meshwork under direct gonioscopic visualization to improve aqueous outflow. The procedure does not involve "goniopuncture" as a separate or necessary component 1.

Clinical Applications and Efficacy

Primary Open-Angle Glaucoma

• Partial (120-degree) goniotomy achieves equivalent IOP reduction compared to complete (360-degree) goniotomy, with mean IOP reductions of approximately 38-46% from baseline 2
• The 120-degree approach demonstrates a significantly lower incidence of hyphema compared to 360-degree goniotomy (P < 0.0001), making it a safer initial approach 2
• At 12-month follow-up, goniotomy achieves complete success rates of 42.1% and qualified success rates of 78.9% in eyes with prior failed glaucoma surgery 3

Steroid-Induced Glaucoma

• Goniotomy should be considered as initial surgical treatment for persistent steroid-induced glaucoma, achieving IOP control below 18 mmHg without medications for an average of 11.5 years 4
• Both gonioscopy-assisted transluminal trabeculotomy (GATT) and excisional goniotomy demonstrate sustained IOP reductions at 24 months in steroid-induced glaucoma, with mean IOP of 12.9±3.5 mmHg for GATT and 14.3±4.1 mmHg for goniotomy 5

Pediatric Glaucoma

• Goniotomy is particularly successful in previously unoperated cases of primary infantile glaucoma that become apparent postnatally but before age 1 year 6
• The procedure is equally effective and safe compared to trabeculotomy ab externo, though goniotomy requires adequate corneal clarity for direct angle visualization 6

Role Within Treatment Algorithm

When to Consider Goniotomy

According to the American Academy of Ophthalmology guidelines, goniotomy falls under the category of minimally invasive glaucoma surgery (MIGS) and represents an alternative to traditional filtration surgery 1.

The procedure should be considered when:

• Trabecular meshwork dysfunction is the primary mechanism of IOP elevation 4, 3
• Patients have failed medical management but require less aggressive intervention than trabeculectomy 1
• Adequate angle visualization is possible on gonioscopy 6
• Prior glaucoma surgeries have failed and repeat intervention is needed 3

Combination with Cataract Surgery

• Combining goniotomy with phacoemulsification provides additional IOP lowering benefit compared to goniotomy alone in some cases 2
• The combination of phacoemulsification with 120-degree goniotomy resulted in lower final IOP compared to 120-degree goniotomy alone (P = 0.0002) 2
• This aligns with broader evidence that cataract extraction alone can lead to substantial IOP lowering in glaucoma patients 1

Safety Profile and Complications

Common Complications

• Transient hyphema is the most common complication, occurring more frequently with 360-degree compared to 120-degree goniotomy 5, 2
• Approximately 10% of GATT eyes required surgical evacuation of hyphema 5
• Transient IOP elevation occurs in 7.9% of cases 3
• Corneal edema occurs in 5.2% of cases 3

Long-Term Safety

• No significant long-term complications were reported in patients followed for an average of 11.5 years after goniotomy for steroid-induced glaucoma 4
• The procedure demonstrates a favorable safety profile compared to traditional filtration surgery 1

Clinical Decision-Making Algorithm

For primary open-angle glaucoma:

1. Start with 120-degree goniotomy (lower hyphema risk, equivalent efficacy to 360-degree) 2
2. Consider combining with cataract surgery if significant cataract is present 2
3. Reserve 360-degree goniotomy for cases where 120-degree approach fails 2

For steroid-induced glaucoma:

1. Consider goniotomy as initial surgical treatment after discontinuing steroids 4
2. Both GATT and excisional goniotomy are effective options 5

For pediatric glaucoma:

1. Use goniotomy as first-line surgical treatment if corneal clarity permits adequate angle visualization 6
2. Consider trabeculotomy if corneal edema prevents adequate visualization 6

Important Caveats

• Goniotomy requires adequate angle visualization - if the cornea is too cloudy to visualize the angle structures, alternative procedures like trabeculotomy should be considered 6
• The procedure is most effective when trabecular meshwork dysfunction is the primary pathology, not when extensive peripheral anterior synechiae or other structural angle abnormalities are present 1
• Older age is associated with better surgical success rates in patients with prior failed glaucoma surgery 3
• The modest IOP reduction achieved (typically mid-to-upper teens postoperatively) may be insufficient for patients requiring very low target pressures 1