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Komzak et al. Mini-invasive Surg 2021;5:13 I http://dx.doi.org/10.20517/2574-1225.2020.103 Page 9 of 14

medication reduction so far and this will need to be taken into account when considering its use in patients
with a high medication burden.

Ab-interno canaloplasty: Safety profile
[12]
Safety appears to be favourable, and according to Heersink et al. , inflammation was the most common
adverse event in the combined group and occurred in 6% of participants, while loss of visual acuity was the
most common adverse event in the control group, occurring in 8% of participants.

Trabectome: Mechanism of action and efficacy
Trabectome or ab-interno trabeculectomy achieves an increase in aqueous humor outflow through the
trabecular meshwork by applying a 0.8 W electrical current in order to ablate the trabecular meshwork.
Access to the anterior chamber is achieved through a clear corneal incision and gonioscopy is used
intraoperatively to visualise the trabecular meshwork. Trabectome and ABiC are significantly differentiated
from the other trabecular microbypass techniques, as no indwelling devices are left in the eye after the
[13]
operation. Esfandiari et al. demonstrated the efficacy of Trabectome when compared against iStent
implantation (both with phacoemulsification), and after 24 months a mean IOP of 13.9 ± 3.3 mmHg
was achieved in Trabectome patients (n = 154) compared with 16.8 ± 2.8 mmHg in iStent (n = 110)
from a baseline of 15.3 ± 3.1 mmHg in both groups. Medication burden was 0.7 ± 1.0 and 1.7 ± 1.2 in
the trabectome and iStent groups, respectively, at 24 months. In addition, the proportion of eyes with an
[13]
unmedicated IOP of ≤ 21 mmHg was 53% and 16.6% in the trabectome and iStent eyes, respectively .
Trabectome has also demonstrated efficacy in pseudoexfoliative glaucoma. Avar et al. investigated
[14]
Trabectome performed on patients either as a solo procedure or with concomitant cataract extraction (in
combined data) described a significant IOP lowering effect in 28% of patients with POAG and 26% with
pseudoexfoliative glaucoma, as well as a significant medication reduction in 32% and 29%, respectively. The
[14]
median follow-up period in this study was 3.5 years .
Gonioscopy assisted transluminal trabeculotomy
Gonioscopy assisted transluminal trabeculotomy (GATT) is a procedure where a circumferential
trabeculotomy is performed of the trabecular meshwork, by running a suture the entire length of Schlemm’s
canal, retrieving and pulling the distal tip while applying traction to the proximal end of the suture. A
study of XEN compared with GATT (both with or without cataract extraction, in combined data) showed
that IOP was reduced from 24.9 ± 5.8 mmHg to 15.3 ± 3.8 mmHg at 24 months post-operatively, and
medications were reduced from 3.3 ± 0.6 to 1.2 ± 0.4. This is compared to a reduction in IOP from 24.4 ±
4.3 mmHg to 14.2 ± 2.2 mmHg at 24 months and medication reduction from 3.4 ± 0.5 to 2.0 ± 2.2 over the
same period for the XEN gel stent. Transient hyphaema was the most common post-operative complication
[15]
following GATT, occurring in 28% of patients .

Excisional goniotomy
Excisional goniotomy or trabeculotomy facilitates increased aqueous outflow by utilising a device such
as the Kahook Dual Blade (KDB, New World Medical, Rancho Cucamonga, CA) to incise the trabecular
meshwork and in theory avoid the thermal damage associated with Trabectome or leaving remnant
trabecular meshwork leaflets in-situ such as with GATT. In a 315-eye study comparing both iStent and
Kahook Dual Blade in combination with phacoemulsification found that the mean IOP reduction at 12
months was 5.0 mmHg compared with 2.3 mmHg in the iStent group (P < 0.001) and mean medication
reductions were similar in both groups with 1.03 and 0.97 in the Kahook Dual Blade group and the iStent
group, respectively. Transient IOP elevation and transient anterior chamber inflammation were the most
complications following KDB, both occurring in 1% of patients .
[16]