Surgical intervention for childhood glaucoma

A retrospective study supports the safety and effectiveness of single-incision ab interno trabeculotomy for treating childhood glaucomas - particularly primary congenital glaucoma.

This article was reviewed by Alana L. Grajewski, MD

Single-incision ab interno trabeculectomy with the Trab360 (SightSciences) provided safe and effective treatment for childhood glaucomas, according to the findings of a retrospective multicenter study.

The research, which was published in the January 2020 issue of the American Journal of Ophthalmology [Areaux RG Jr, Grajewski AL, Balasubramaniam S, et al. Am J Ophthalmol. 2020;209:178-186] analyzed outcomes from 46 eyes of 41 patients who ranged in age from one to 325 months (median 12 months) when they underwent the minimally invasive glaucoma surgery (MIGS). 

After a median follow-up of 14.5 months, median IOP was reduced from 30 mm Hg (range 18 to 49 mm Hg) preoperatively to 18 mm Hg (range 5 to 40 mm Hg).

Furthermore, the surgery was associated with a decrease in medication burden. Median number of medications fell from 2.5 (range 0 to 5) preoperatively to 1 (0 to 4). 

Success, defined as postoperative IOP ≤ 24 mm Hg with or without medications, no additional surgery needed to control IOP, and absence of devastating or severe complications was achieved in two-thirds of eyes.

With eyes categorized by diagnosis, subgroup analyses showed the highest success rate was achieved in eyes with primary congenital glaucoma (PCG), which was also the most common diagnosis in the series (45.5%).

Of 21 eyes with PCG, 81% met the criteria for success. Excluding three eyes with PCG that had undergone prior glaucoma surgery, the success rate was 83.3%. 

Cyclodialysis occurred in two eyes (4.3%). One required surgical treatment and the other resolved spontaneously. 

There were no other significant complications, according to the study.

Early research
The study authors pointed out that theirs is the first study to critically evaluate outcomes of the Trab360 procedure to treat childhood glaucomas. They observed that the success rates reported correspond well with those published previously for childhood glaucoma angle surgery. 

Noting that the MIGS device used in the surgeries has been replaced by its manufacturer with new technology (OMNI Surgical System), the authors also suggested that the findings of the study could be generalized to any “sufficiently similar technique” of single-incision ab interno trabeculectomy. 

However, they also noted that there is a learning curve for safe use of the Trab360 device and that the procedures were performed by surgeons with significant experience performing angle surgery in children.

More details
The children were operated on by one of four surgeons practicing at four different academic centers. Children needed to have sufficient corneal clarity to undergo the ab interno procedure. To be included in the retrospective analysis, they were required to have at least three months of postoperative follow-up. 

A variety of childhood glaucoma types were represented in the series. According to the study, subgrouping of the cases by diagnosis was based on the World Glaucoma Association’s Childhood Glaucoma Classification System.

Aside from PCG, other diagnoses were glaucoma associated with a nonacquired systemic disease or syndrome (17%), juvenile open-angle glaucoma (13%), glaucoma following cataract surgery (11%), glaucoma associated with an acquired condition (8.5%), and glaucoma associated with a nonacquired ocular anomaly (4%).  

Researchers pointed out that success was achieved in 83% of eyes with juvenile open-angle glaucoma, 60% of those with glaucoma following cataract surgery, 50% of those with glaucoma associated with a nonacquired systemic disease or syndrome, and 50% of those with glaucoma associated with an acquired condition. 

Neither of the two eyes with glaucoma associated with a nonacquired ocular anomaly achieved success.

Acknowledging that the numbers of eyes in each subgroup is small, the authors suggested that the MIGS procedure could be considered reasonable for treatment of eyes with uveitic glaucoma or glaucoma after cataract surgery prior to resorting to a glaucoma drainage device, trabeculectomy, or a cyclodestructive procedure. 

The most common reason for failure was the need for additional surgery, either for IOP control or to address complications. Of the 15 failures, 12 occurred within the first three months after surgery.

Safety considerations
The authors warned that good surgical technique and caution when operating on eyes with high-risk angles are critical to avoid cyclodialysis. 

Both eyes that developed cyclodialysis had angle anomalies that could have made them susceptible to cyclodialysis cleft formation caused by placing traction on the trabecular meshwork. 

Specifically, the authors urged caution performing the surgery in eyes with extreme bupthalmos, advanced uveitis, or anterior segment dysgenesis, or if the angle anatomy is distorted, anomalous, or obscured by peripheral anterior synechiae.

Conclusions
The authors acknowledged that the research was subject to the limitations inherent in a retrospective analysis. They also observed the need for cost analyses, but suggested that the cost associated with the device itself could be offset by its benefits relative to a 360-degree ab externo procedure for reducing operating time and duration of general anesthesia exposure in children.

Alana L. Grajewski, MD
E: agrajewski@miami.edu
None of the study authors had any financial conflict of interest to report.