Microhook trabeculotomy (μTLO) has surgical success noninferior to that of “the pioneer” of MIGS — trabectome (TOM), according to a study published in Ophthalmology Glaucoma

In a large, multicenter observational analysis, researchers reviewed records of patients treated for primary or secondary open-angle glaucoma from January 2014 to March 2020 at 10 centers, including 392 patients who received μTLO, and 553 who underwent TOM. The main outcome measure comparing TOM with ab interno μTLO was surgical success, defined as 1-year postoperative intraocular pressure (IOP) of 5 mm Hg to 21 mm Hg, IOP decreased by at least 20%, and no further glaucoma surgeries were needed during the first year.

The team performed a data analysis with 1:1 propensity score matching with 4 different methods to adjust for factors such as age, glaucoma type and drug score, incision of 1 or 2 trabecular meshwork quadrants, preoperative IOP, mean deviation of Humphrey visual field test, sex, and other factors. Investigators found that statistical difference in surgical failure risk for μTLO compared with TOM “was -12.1 to +9.5% in matching, −12.7 to +11.1% in IPTW (inverse probability of treatment weighting), -12.2 to +7.0 in stratification, and -9.7 to +8.1% in regression adjustment, all of which fell within the predetermined non-inferiority margin of 15%.”

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Cost factors were also assessed, as the TOM system is based on a disposable surgical device, but μTLO employs a reusable metal instrument. In US dollar equivalency to Japanese Yen, TOM’s dedicated handpiece is priced at $742 for each eye, or surgical case, although μTLO costs $769 for the initial purchase of the reusable microhook unit.

Only 1 previous investigation has specifically compared TOM with μTLO, resulting in a 1-year surgical success rate of 81.4% with TOM, and 60.7% for μTLO. However, it included a significantly greater percentage of patients with exfoliation glaucoma, and was a single-center analysis that did not adjust for confounding elements including various kinds of glaucoma.

Participant age, in median and interquartile range, for those who underwent TOM was 69 (Q1 =57, Q3=78); and age for patients receiving μTLO was 70 (Q1 =60, Q3=77), not a statistically significant difference (P =.78). Surgical complications did not significantly differ between the two cohorts regarding elevated IOP or layered hyphema.

Propensity score analysis is also called quasi-randomized analysis, and cannot take into account unknown confounding factors. Another limitation was a 1-year follow-up — TOM and μTLO use different techniques to thermally ablate or incise trabecular meshwork, and longer-term outcomes may vary due to recuperation or scarring. A strength is its multicenter design. Given that this analysis found μTLO not to be inferior to TOM 1 year after surgery, and provided comparable surgical success, “μTLO could contribute to the reduction of medical expenditure compared with other types of MIGS.”

Disclosures: The study authors have declared affiliations with the biomedical, pharmaceutical, and medical device industries. Please see the original reference for a full list of authors’ disclosures.


Mori S, Tanito M, Shoji N, et al. Non-inferiority of microhook to trabectome: trabectome vs. ab interno microhook trabeculotomy comparative study (TramTrac Study). Ophthalmol Glaucoma. Published online November 25, 2021. doi:10.1016/j.ogla.2021.11.005