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

Abstract

Trabeculotomy with the Kahook knife is anew 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. A total of 37eyes of 37patients were examined when IOP was > 21 mm Hg in at least 2examinations despite the maximum tolerable Meds applied. Cat-TO was performed in 18phakic eyes (primary open-angle glaucoma, POAG = 11, pseudoexfoliation glaucoma, PEX = 5, ocular hypertension, OHT = 2). In 19pseudophakic 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 evaluated2, 6 and 12months postoperatively. The IOP was significantly reduced from preoperatively to 2months 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 after6 and 12months was significantly greater in the Cat-TO group compared to the TO group (p = 0.02). The IOP and Meds did not change significantly from2 to 6months. After Cat-TO, qualified success after 12months for IOP ≤ 18 mm Hg was 61% (11/18) and for IOP ≤ 16 mm Hg 28% (5/18). After TO, qualified success after 12months 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 7patients after TO and 2patients after Cat-TO (IOP two times > 21 mm Hg). The first year results show that TO as well as Cat-TO are effective minimally invasive interventions to delay or even avoid afiltrating operation. In case of Meds intolerance and target IOP ≤ 16 mm Hg Cat-TO is not sufficient.