Trabeculotomy opening size and IOP reduction
after Trabectome® surgery
Jens F. Jordan
Christian van Oterendorp
Received: 3 November 2016 /Revised: 4 April 2017 / Accepted: 18 April 2017 /Published online: 20 May 2017
The Author(s) 2017. This article is an open access publication
Background Trabeculotomy with the Trabectome® is an
effective surgical procedure to lower intraocular pressure
(IOP). However, in some patients it does not lead to a
significant IOP reduction despite a gonioscopically well
visible opening of Schlemm’s canal. This study investi-
gated whether the size of the trabeculotomy opening
and other parameters, including anterior chamber depth
(ACD) are related to IOP reduction.
Methods Retrospective observational case series with 93 eyes
of 93 patients who underwent Trabectome surgery.
Trabeculotomy opening and ACD were measured with an
anterior segment swept source OCT. IOP was taken pre-
operatively and at a single follow-up visit [follow-up time
125 ± 66 days (mean ± SD)]. The relationship between IOP
reduction and OCT parameters and possible confounding
factors was analyzed in a multiple linear regression model.
Results The trabeculotomy opening size did not correlate with
IOP reduction (slope of regression line = 0.0016; 95% confi-
dence interval of slope: −0.025 to 0.028). The same applied
for all other parameters tested, including ACD, which showed
a tendency towards better IOP reduction with a deeper AC
(slope = −1.9; 95% confidence interval: −5.54 to 1.73).
Comparison between the 1st and 4th quartile of the
trabeculotomy opening showed a significantly higher ACD in
the largest trabeculotomy opening quartile (3.32 ± 0.05 mm vs.
3.16 ± 0.04 mm; p =0.031).
Conclusions The fact that the trabeculotomy opening size did
not correlate with IOP reduction points to the poorly under-
stood role of the intrascleral aqueous outflow pathway in
glaucomatous IOP elevation. A deeper AC might be a factor
promoting a larger trabeculotomy opening.
Minimally invasive glaucoma surgery
Various morphological and functional alterations of the
trabecular meshwork (TM) are known to increase aqueous
outflow resistance in open-angle glaucoma [1, 2]. Thus, par-
tial opening of Schlemm’s canal by ablation of the TM with
the Trabectome is supposed to facilitate aqueous drainage to
the episcleral veins . Trabectome surgery has been proven a
safe and effective procedure to significantly lower intraocular
pressure (IOP) in open-angle glaucoma patients [4–6]. During
the early post-operative course, the original size of the
trabeculotomy opening decreases to a variable degree by re-
closure of the TM or formation of anterior synechiae (and
personal observation). After 2 years of follow-up, a total of
approximately 20 to 40% of all cases (depending on glaucoma
type and lens status) fail to develop a significantly lower IOP
. Interestingly, some of these failed cases still exhibit a
Electronic supplementary material The online version of this article
(doi:10.1007/s00417-017-3683-0) contains supplementary material,
which is available to authorized users.
* Christian van Oterendorp
Eye Center, Medical Center, Faculty of Medicine, University of
Freiburg, Freiburg, Germany
Augenarztpraxis Drs. Neuburger/Burau/Schmidt, Achern, Germany
Berufsausübungsgemeinschaft (GbR) Dr. med. Michael A. Vobig,
Prof. Dr. med. Jens Jordan, Frankfurt, Germany
Department of Ophthalmology, University Medical Center
Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
Graefes Arch Clin Exp Ophthalmol (2017) 255:1643–1650