This retrospective review included 217 patients who underwent ab interno trabeculectomy by Trabectome or trabeculectomy with intraoperative mitomycin as an initial surgery for medically uncontrolled glaucoma. Patients who underwent trabeculectomy had a greater success rate, with lower mean IOP and less need for supplemental antiglaucoma medications at all time points, but also had more complications.
These results suggest that the ab interno procedure is better suited for moderate IOP reduction than long-term, major IOP reduction, or as a substitute for medication when side effects are a problem. A comparative study of the Trabectome and other ab interno procedures, such as canaloplasty, would be useful in determining the true value of ab interno procedures as a mainstay in managing IOP in open-angle glaucoma.
Failure was defined as IOP greater than 21 mmHg or 5 mmHg or less on two consecutive follow-up visits after one month, less than 20 percent reduction below baseline on two consecutive follow-up visits after one month, additional glaucoma surgery or loss of light perception vision.
The two-year success rate for the ab interno group was 22.4 percent, compared to 76.1 percent for the trabeculectomy group. IOP decreased 43.5 percent from baseline (28.1 ± 8.6 mmHg to 15.9 ± 4.5 mmHg) in the ab interno group and 61.3 percent from baseline (26.3 ± 10.9 mmHg to 10.2 ± 4.1 mmHg) in the trabeculectomy group.
With the exception of hyphema, postoperative complications were more common in the trabeculectomy group (P < 0.001). Hyphema and early IOP spikes occurred in both groups. Inadvertent creation of a cyclodialysis cleft occurred in one ab interno eye. However, other complications, such as early and persistent hypotony, wound leak, shallow anterior chamber, conjunctival buttonhole, corneal abrasion and bullous keratopathy, occurred only in the trabeculectomy group.
More glaucoma procedures were performed after ab interno trabeculectomy (50/115 eyes, 43.5 percent) than after trabeculectomy (11/102 eyes, 10.8 percent; P < 0.001).
The authors conclude that due to its higher safety profile, ab interno trabeculectomy may be a viable alternative in those with early-stage disease or at high risk of hypotony or long-term bleb complications. Further studies are needed to ascertain the effect of ab interno trabeculectomy in combination with other procedures.