[Ab interno trabeculotomy without/with cataract operation-An alternative treatment before or instead of trabeculectomy in patients with high intraocular pressure?].

BACKGROUND: Trabeculotomy with the Kahook knife is a new ab interno minimally invasive glaucoma surgery (MIGS) procedure. The MIGS are usually performed in early to intermediate glaucoma eyes. In this retrospective study we analyzed the intraocular pressure (IOP) and topical glaucoma eye drop therapy (Meds) reduction achieved by the Kahook trabeculotomy (TO) without (n = 19) or with (n = 18) combined cataract operation (Cat-TO) as initial treatment before or to avoid filtering surgery.

MATERIAL AND METHODS: A total of 37 eyes of 37 patients were examined when IOP was > 21 mm Hg in at least 2 examinations despite the maximum tolerable Meds applied. Cat-TO was performed in 18 phakic eyes (primary open-angle glaucoma, POAG = 11, pseudoexfoliation glaucoma, PEX = 5, ocular hypertension, OHT = 2). In 19 pseudophakic eyes (POAG = 12, PEX = 6, OHT = 1) an isolated TO was executed. Complete success (no Meds) and relative success (irrespective of Meds) for IOP ≤ 21 mm Hg, ≤ 18 mm Hg, ≤ 16 mm Hg were evaluated 2, 6 and 12 months postoperatively.

RESULTS: The IOP was significantly reduced from preoperatively to 2 months after Cat-TO as well as after TO (Cat-TO: 26.8 ± 5.9 mm Hg to 16.0 ± 2.9 mm Hg, p < 0.001; TO: IOD 28.2 ± 5.6 mm Hg to 16.3 ± 3.5 mm Hg, p < 0.001). Meds reduction after Cat-TO as well as after TO was not significant (Cat-TO: 2.1 ± 1.3 to 1.3 ± 1.3, p = 0.11; TO: Meds 2.7 ± 1.1 to 2.2 ± 1.3, p = 0.23); however, Meds reduction after 6 and 12 months was significantly greater in the Cat-TO group compared to the TO group (p = 0.02). The IOP and Meds did not change significantly from 2 to 6 months. After Cat-TO, qualified success after 12 months for IOP ≤ 18 mm Hg was 61% (11/18) and for IOP ≤ 16 mm Hg 28% (5/18). After TO, qualified success after 12 months for TO was 47% (9/19) for IOP ≤ 18 mm Hg and 26% (5/19) for IOP ≤ 16 mm Hg. The intervention was not sufficient for 7 patients after TO and 2 patients after Cat-TO (IOP two times > 21 mm Hg).

CONCLUSION: The first year results show that TO as well as Cat-TO are effective minimally invasive interventions to delay or even avoid a filtrating operation. In case of Meds intolerance and target IOP ≤ 16 mm Hg Cat-TO is not sufficient.