minimally invasive glaucoma surgery

1. Minimally invasive glaucoma surgery
( M I G S )
By S u h a i b A l i J a w a d
Ophthalmic resident doctor
2nd stage student - iraqi board

2. Definition: ( FDA )
IOP-lowering surgery with the following
characteristics that distinguish it from traditional
glaucoma surgery:

3. Offer more modest results than traditional
glaucoma surgery, but with the benefit of a safer
risk profile.
These procedures are currently targeted at
patients with mild-to-moderate open-angle glaucoma.
MIGS procedures by definition should preserve
the conjunctiva from surgicaldissection.
Complications such as (hypotony, hyphema, infections
of the bleb, revisions of the bleb, and endophthalmitis ) may occur in
up to 35% of patients treated with conventional glaucoma
Surgery , MIGS may avoid those complications.
Can provide a method of treatment for glaucoma
patients that decreases reliance on medications
without the safety risks of more invasive procedures.

4. Indications:
Patients that are candidates for MIGS are:
• Patients with mild-moderate glaucoma
Primary open-angle glaucoma, pseudoexfoliation glaucoma, or
pigmentary dispersion glaucoma .
• Glaucoma is uncontrolled with maximum pharmacologic treatment
or there are barriers preventing adequate medication dosing .
• Age greater than 18 .
• Patients with clinically significant cataract, as surgery may be
performed simultaneously.
Contraindications:
Relative contraindications for this procedure may include :
• angle-closure glaucoma .
• secondary glaucoma > neovascular glaucoma.
• moderate-advanced glaucoma .
• previous glaucoma surgery .
• severely uncontrolled IOP .

5. Types :
Bypass trabecular meshwork resistance to
aqueous flow with stents into Schlemm’s canal
(iStent, Hydrus).
Via drainage into the suprachoroidal space
(Cypass) .
By excision of TM itself (Trabectome) .
Endo-cylodiode uses directly observed ablation of
ciliary processes under endoscopic control .
Via drainage into the subconjactival space
(XEN gel stent) .

6. Currently, three devices (iStent, iStent inject
[Glaukos Inc., USA], and Hydrus [Ivantis Inc., USA])
target the juxtacanalicular part of the trabecular
meshwork, which is believed to represent the greatest
resistance to aqueous humor outflow in patients with
open-angle glaucoma (OAG).

7. iStent
The smallest FDA approved implant EVER made .

9. iStent Trabecular Micro-Bypass
Stent (Glaukos)
1 mm x 0.33 mm
Snorkel
0.3 mm
Lumen 120 µm
Self-Trephining Tip
1 mm x 0.33 mm
Snorkel: 0.25 mm x 120 µm (bore
diameter).
Weight: 60 µg.
Surgical grade non-ferromagnetic
Titanium.
Heparin-coated to promote self-
priming and facilitate outflow.
iStent® is FDA approved in the U.S in 2012
Provided pre-loaded in an inserter.

10. iStent: Indication
In conjunction with
cataract surgery
Mild to moderate open-
angle glaucoma
Currently treated with
ocular hypotensive
medication

11. iStent: Mechanism
Designed to improve
aqueous outflow through
the natural physiologic
pathway
Creates a bypass
through trabecular
meshwork to
Schlemm’s canal

12. iStent
The leading edge of iStent is inserted through the trabecular meshwork into
Schlemm’s canal at the nasal position where the tip of the stent is pointing
inferiorly.
Usally more than one stents are required for adequate IOP lowering effect.

14. At 12 months:
68% of iStent subjects
with IOP ≤ 21 mm Hg
without medication vs.
50% with cataract
Its good % , but actually the
majority is from cataract extraction.
surgery alone .
Ophthalmology. 2011 Mar;118(3):459-67.
Percent of Eyes With IOP ≤ 21 mm Hg Without Medication
100
80
60
40
20
0
Cataract Surgery iStent

15. Percent of Patients on Ocular Hypotensive Medication
At 12 months:
15% of iStent with phaco vs.
35% phaco only group on
medication .
100
50
0
Cataract Surgery iStent
Ophthalmology. 2011 Mar;118(3):459-67.

16. Katz et al evaluated the effect of the implantation of either one, two or three iStents during
stand-alone procedures without PE/IOL in 119 patients with OAG , 34 subjects received one,
41 two, and 40 three iStents.
At month 12 ,an unmedicated IOP of ≤18 mmHg and an IOP reduction of ≥20% without ocular
hypotensive medication were achieved by 89.2%, 90.2%, and 92.1% of eyes in the one-, two-,
and three-stent subgroups, respectively.
At month 18, mean unmedicated IOPs were 15.9±0.9 mmHg, 14.1±1.0 mmHg, and 12.2±1.1
mmHg for the one-, two-, and three-stent subgroups, respectively.

17. In a randomized prospective study conducted by Fea, efficacy and safety of iStent combined with
cataract surgery were compared with a stand-alone cataract surgery (PE/IOL).
At month 15, mean IOP in the iStent arm was 14.8±1.2 mmHg and 15.7±1.1 mmHg in the PE/IOL
arm, respectively .
At month 16 after the wash-out of any study medications, mean IOPs increased to 16.6±3.1
mmHg in the iStent arm and 19.2±3.5 mmHg in the PE/IOL arm.

18. In a prospective, non-randomized consecutive case series of 62 eyes with
(POAG, PEX, secondary glaucoma, post-traumatic glaucoma, and ocular
hypertension) which received iStent during a combined procedure with
PE/IOL
Neuhann reported a decrease of mean IOP from 24.1±6.9 mmHg on a
mean of 1.8±0.9 medications at baseline to 14.9±2.3 mmHg at month 36.
Medications were completely stopped in 74% of eyes at month 36.

19. Safety profile and adverse events of
iStent
• Blood reflux
from Schlemm’s canal into the anterior chamber is a common
process that occurs intraop. This reflux is a positive and normal sign.
• Minor adverse events include temporary obstructions of the
iStent, which were resolved in most cases by Nd-YAG laser
treatment, and malpositioned micro-stents.
• No postoperative hypotony, loss of endothelial cells, inflammation
• EXPENSIVE : 1000$ for each stent , you may need up
to 3 stent implantation .
• Limits future surgeries : eg.canaloplasty

20. so-called “intracanalicular scaffold”

21. Mechanism & complications :
The stent bypass TM & dilates Schlemm canal by approximately
166 mm along the length of device .
It is implanted through a clear corneal incision under direct
gonioscopic view.
It creates a maximum SC dilation of approximately 4-5 times the
natural cross-sectional area of SC.
Dilates Schlemm’s canal for approximately three clock hours
in the nasal quadrant, thereby enhancing aqueous outflow.
Reported complications included two cases of iris damage +
PAS and three cases of mild hyphema that resolved within a week.

22. Surgical technique
manual inserter
through the TM into SC
1 mm inlet of the microstent
remains outside SC
TM bypass
Canal
dilatation

24. 1 mm inlet of the microstent
remains outside SC

25. Studies :
HYDRUS I study :Preliminary1year results - meanIOP
lowering of 20% in patients treated with the Microstent
alone, with a concurrent 69% reduction in use of
glaucoma medications.
HYDRUS II study : Compared phacoemulsification
alone and phacoemulsification combined with
Microstent . At the two-year follow up period, 73%
of the treatment group were medication free
compared with 38 % of the control group .
HYDRUS III study : Compares phacoemulsification
combined with either the Hydrus or the first-generation
iStent.
HYDRUS IV study : is a FoodandDrugAdministration-
approved trial that is currently on going.

26. Ophthalmology Volume 122, Number 7, July 2015

27. CyPass :
CyPass suprachoroidal shunt (Alcon Inc., Fort Worth,
TX, USA)
Implanted from an ab interno approach under
gonioscopic view.Conjunctival/scleral dissection is avoided.
FDA approved in 2016 .
Can be placed prior to or after most other glaucoma
sugeries.?

28. The CyPass is 6.35mm long and has a single lumen ,
non-traumatic .
Made of polyimide and designed to be both biocompatible
and non-biodegradable.
Aqueous can enter the distal lumen residing in the anterior
chamber, and pass into the suprachoroidal space through
multiple fenestrations along the length of the implant.
OCT has been used to confirm
device placement in the supra-
choroidal space with a
surrounding fluid pocket.
• Better control of IOP
• Minimal post op. spikes
Cleft size also important.
The goal of the device is to create
a controlled cyclodialysis with stented
outflow to the supraciliary space.

29. Efficacy and safety of CyPass
Study published by Hoeh et al involved 167 eyes of 142 patients. Mean baseline
IOP of the patient cohort was 20.2±6.0 mmHg. The eyes were analyzed in two
subgroups ,one with medicated baseline IOP levels of ≥21 mmHg and another with
baseline IOP levels of <21 mmHg.
Overall, mean IOP decreased from 20.2±6.0 mmHg to 15.9±3.1 mmHg at 12 months.

30. The another study was a multicenter, interventional randomized trial. Subjects with
OAG and cataract with mean IOP (21-33 mmHg). Mean preoperative IOP was
24.5±3.0 mmHg. At month 24, IOP was reduced by 7.4 mmHg in the micro-stent
arm versus 5.4 mmHg in the phacoemulsification arm. Of the patients in the micro-
stent arm, 85% did not require medications at month 24 and the mean number of
medications was reduced by 67% (0.2±0.6 medications). 77% of subjects in the
micro-stent arm and 60% of subjects in the phacoemulsification arm achieved an
unmedicated IOP decrease versus baseline of ≥20%.

31. Safety profile and adverse events of CyPass
the two most frequent complications were :
• early hypotony in 13.8% of patients, which resolved within 1
month and an IOP increase of ≥10.0 mmHg (3.0%).
• An obstruction of the implant was seen in 5.4% of the
patients.
• Other adverse events reported :Cataract progression ,
transient hyphema ,transient (≤30-day duration) best-
corrected visual acuity loss of ≥2 lines , iritis and corneal
edema. malpositioning and migration/dislocation were
observed.

32. XEN gel stent
subconjunctival filtration pathway
• ab-interno bleb in refractory glaucoma .
• By (Allergan plc, Dublin, Ireland) .
• Made of porcine (modified) collagen cross-linked with glutaraldehyde .
• Investigational device that is currently undergoing clinical trials.
• 6 mm in length and has a lumen diameter of 45 μm.
• stent is stiff when dehydrated but becomes soft and flexible when it
comes into contact with the aqueous humor.
• three different lumen diameters of the stent were investigated :
(45 μm, 63 μm, and 140 μm), however, only the 45 μm type is
currently used.

33. XEN gel stent
subconjunctival filtration pathway
• The procedure is limited to eyes without conjunctival scarring.
• The implantation procedure can be done as stand-alone, or in
combination with cataract surgery.
• The XEN gel stent is placed through a small, self-sealing,clear corneal
incision using an inserter. The device is implanted into the
Subconjunctival Space opposite the incision, thus, the procedure does
not disrupt the conjunctival and subconjunctival tissue.
• A fistula is created, resulting in a bleb.
• MMC used.
• Regarded as a modified ab interno TE .

34. E s t a b l i s h e d E f f e c t i v e n e s s
• At 12 months, 76.3% of subjects achieved ≥ 20% mean
diurnal IOP reduction on the same or fewer number of
medications vs baseline.
In combined surgery :one year results 30% IOP reduction
( from 20.8 to 14.4 mmhg )
60% medication reduction
• Three years results :
40% IOP reduction.
75% medication reduction.
33% of patients were using no medications at 24 months
5% required additional glaucoma surgery

36. Adverse events occurred in three eyes.
• Two eyes did not complete the procedure (280°
subconjunctival hemorrhage and XEN extrusion during
repositioning).
• The third case had an encapsulation of the bleb 5 months
after the surgery.
• Hyphaema occur
• Short term and long term hypotony .
Safety profile and adverse events of XEN gel

38. The Trabectome:
inner wall
It was introduced in 2004 that allows
a trabeculotomy to be performed via an internal approach.

39. Microelectrocautery handpiece designed to ablate trabecular meshworkand
Schlemm’s canal inner wall tissue over an area of several clock hours..
The device is a disposable handpiece that is activated by foot pedal control
connected to a console that allows the surgeon to adjust infusion, aspiration, and
dissipated electrosurgical energy.

40. •A clear corneal near-limbal 1.6-mm keratome incision is made. Viscoelastic may
or may not be necessary to allow safe insertion of the instrument tip to allow
infusion flow and AC stability.
• Surgical tip is advanced under gonioscopic control to engage nasal meshwork
before activating aspiration and ablation by progressively depressing the foot
pedal and rotating the tip90° parallel to theiris just anterior to the Scleral spur.
• Ablation with continual infusion and aspiration is performed along an arc of
30 ° to 60° up to 120° to ensure Complete viscoelastic removal thereafter.

41. Side Effects and Complications : Descemet’s ,Ciliary body ,
Reflux bleeding, hyphema
Zonule
Injury,

42. Review of 115 Trabectome patients vs. 102 trab-
MMC patients.
Success rates (IOP<21 mmHg or >20% reduction)
at 2 years:
22.4% for trabectome and 76.1% for trab
Trabectome had 100% hyphema POD #1, plus 4.3%
other complications, compared to 35.3% Complication
rate for trabeculectomy.

43. EndoscopicCyclophotocoagulation:
•In cases of refractory glaucoma
•Patients on maximum medical
therapy showing continued
progression of disease were often
considered as appropriate
candidates.
•Patients who had failed filtration
surgery or were considered at high
risk for failure or complications
post-traditional filtration
procedures. • Better visualization of the tissue being treated
• Less destructive method of applying the laser

45. -
• 810-nm diode laser, allows
surgeon to precisely aim
the laser to cause effective
cycloablation of the ciliary
Processes .
• There was much less
destruction (if any) to the
ciliary body muscle .

46. The ICE Procedure
Cataract Extraction
iStent ECP

47. What is ICE?
16.5% IOP
lowering at 3 years
Mansberger. Ophthal. 2012;
119:1826-31.
33% IOP
lowering with
cataract
extraction
Samuelson. Ophthal.
2011;118:459-67.
43% IOP lowering with cataract extraction
Kahook; J Glaucoma. 2007;16:527-30.

48. Mechanisms of ICE?
? Angle widening
? Decreased
aqueous
production
Increased
trabecular
outdlow
Decreased aqueous production

49. • Firstly, the mode of action may be one criterion. iStent, iStent inject, and
Hydrus work by improving aqueous humor outflow at the structure of the
physiological outflow into Schlemm’s canal, while the other options are
generating new and thus probably less physiological outflow pathways into
the suprachoroidal space (CyPass and iStent Supra [Glaukos Inc.]) or the
subconjunctival space (XEN gel).
• Secondly, the safety profile of the different approaches needs to be
considered, especially the risk for generating hypotony.(trabecular is the least
, suprachoroidal and subconjactival are highest).
Furthermore, the implantation of XEN gel stent can be regarded as a
modified ab interno TE with the formation of a bleb and the need for MMC.
A result of these considerations may be to use the Schlemm’s canal micro-stents
in patients with mild to moderate glaucoma, and the suprachoroidal and
subconjunctival devices for the more severe cases of glaucoma .
> Since 1960 , conventional glaucoma surgery by trabeculectomy
still the best.
Conclusion