Abstract
To assess the roles of preoperative intraocular pressure (IOP) level on the IOP reducing efficacy of microhook ab interno trabeculotomy (µLOT), 126 consecutive open-angle glaucomatous eyes (90 primary open angle glaucoma, 36 exfoliation glaucoma) of 126 Japanese subjects (60 men, 66 women; mean age ± standard deviation, 70.5 ± 11.4 years) who underwent µLOT alone (25 eyes, 20%) or combined µLOT and cataract surgery (101 eyes, 80%) were retrospectively included, and subdivided into four groups based on the quartile of preoperative IOP: Q1, ≤15 mmHg; Q2, 15–18 mmHg, Q3, 18–21 mmHg, and Q4, >21 mmHg. Preoperative and 12 months postoperative IOPs and numbers of antiglaucoma medications were compared among IOP groups. Factors associated with postoperative IOP were assessed using multivariate analysis, and the success of IOP control was assessed with various definitions. Postoperatively, IOP was significantly higher in Q3 (p < 0.0146) and Q4 (p = 0.0320) groups than Q1 group, while the number of medications was not significantly different among four IOP groups (p = 0.1966). Older age was associated with lower postoperative IOP, and higher preoperative IOP was associated with higher postoperative IOP, while sex, glaucoma type, surgical procedure, lens status, extent of trabeculotomy incision, and preoperative number of medications were not associated with postoperative IOP. The success rates for IOP ≤ 18 and ≤15 mmHg were higher in lower preoperative IOP groups (i.e., Q1 and Q2) than higher preoperative IOP groups (Q3 and Q4), while the success rate for ≥20% IOP reduction was higher in higher preoperative IOP groups than in lower preoperative IOP groups; the success rate for ≥0% IOP reduction was equivalent among groups. By reviewing the previous studies in ab interno trabeculotomy/goniotomy procedures, positive correlation between preoperative and postoperative IOPs was preserved throughout the studies and surgical procedures. After the µLOT, larger %IOP reduction was achieved in higher preoperative IOP groups than in lower preoperative IOP groups, while postoperative IOP was still lower than in lower preoperative IOP groups.
Highlights
In case series of μLOT, by using multiple regression analyses, we have previously reported that older age, steroid-induced glaucoma, developmental glaucoma, and the absence of postoperative complications were associated with lower final intraocular pressure (IOP); exfoliation glaucoma, other types of glaucoma, and higher preoperative IOP
In all IOP groups, compared with preoperative IOP, postoperative IOP was significantly lower at 12 months (p < 0.0001 in all comparisons) (Table 2)
The %IOP reduction was significantly different among all comparison pairs of Q1-Q4 groups (p < 0.0001–0.0493), except for the comparison between Q2 and Q3 groups (p = 0.9990)
Summary
Trabeculotomy (LOT) lowers intraocular pressure (IOP) by reducing aqueous flow resistance by cleaving the trabecular meshwork (TM) and inner walls of Schlemm’s canal [1]. The blebless mechanism of IOP reducing action in LOT is associated with less chance of devastating visual complications including shallow anterior chamber (AC), bleb leakage, blebitis, choroidal detachment, and hypotony maculopathy than those in mitomycin Cadjuvanted trabeculectomy [2,3]. Ab interno approaches have been adopted for performing LOT procedures [4,5]. In 2015, as an initial case, we performed microhook 4.0/). Trabeculotomy (μLOT), a novel ab interno LOT procedure, in a case with bilateral steroidinduced glaucoma [6]. In an initial 560 eyes, the preoperative IOP of 20.2 mmHg and number of antiglaucoma medications of 2.8 decreased to 13.9 mmHg (31% reduction) and 2.5
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