NON-PENETRATING
GLAUCOMA SURGERY
Dr.Jyoti Shetty
Medical Director,
Bangalore West Lions Superspeciality
Eye Hospital
PRINCIPLE
 Intended to facilitate the
passage of aqueous
humor through the
trabeculum and
Schlemm's canal
bypassing the the juxtacanalicular meshwork
which is the site of
highest resistance to
aqueous outflow without
opening the anterior
chamber and
decompressing the eye.
TRAB MESHWORK
ROOF OF
SCHLEMS
CANAL
SCHLEMS CANAL
ANTERIOR CHAMBER
INDICATIONS
Patients requiring target IOP at moderate
levels between 15-18mmHg with poor
compliance for medical therapy to achieve
the same.
TECHNIQUES
Ab-externo trabeculectomy- Eduardo
Arenas
Viscocanalostomy- Robert Stegmann
Deep sclerectomy -Mermoud
Laser trabecular ablation - Arturo
Maldonado-Bas
Ab-externo trabeculectomy
Involves removal of the diseased
endothelial layer of Schlemm’s canal and
the Juxtacanalicular Trabecular Meshwork
using a diamond microdrill.
Ab-externo trabeculectomy Conjunctival Flap
 A deep scleral flap is
dissected
(2.5x1.5mm) such
that the roof of the
Schlemms Canal is
reached and then it is
unroofed.
1.5mm
2.5mm
 In the floor of the
scleral flap, aqueous
leak will be seen if the
Schlemm’s Canal has
been unroofed .
 Mitomycin-C(0.08%)
is then applied under
the scleral flap.
Scleral
flap
Unroofed Schlems canal
 The diamond
microdrill is then used
to remove the floor of
the Schlemm’s Canal
and the juxtacanalicular meshwork
 Tight conjunctival
closure..
Diamond
Microdrill
According to Arenas, an opening of 100µ
is sufficient for functional drainage as
Aqueous Humour elimination from AC is a
very passive and metabolic process-A big
fistula is not required to control IOP.
DEEP SCLERECTOMY
 Fornix or limbal based
conjunctival flap.
 Superficial scleral flap - 5
x 5 mm ,1/3 of the scleral
thickness (300 microns).
 In order to be able to
dissect down to
Descemet’s membrane
later, the scleral flap is
dissected 1 to 1.5 mm
into clear cornea
5mm
Dissection extended 1-1.5mm
into clear cornea
5mm
 A deep scleral flap is
then dissected to 95%
of remaining
thickness of the
sclera
.
Superficial
Scleral Flap
Deep
Scleral
Flap
 Schlemm’s canal is
unroofed at the level
of the scleral spur to
expose the TM
Descemet’s membrane is carefully
dissected away from the corneal stroma
using a sponge or a spatula
When the anterior dissection is complete,
the deep scleral flap is cut anteriorly
 Endothelium of floor of Schlemm’s canal
and the juxtacanalicular portion of the
trabeculum are peeled off
 When the anterior
dissection is
complete, the deep
scleral flap is cut
anteriorly
 Endothelium of floor of
Schlemm’s canal and
the juxtacanalicular
portion of the
trabeculum are peeled
off
 To avoid a secondary
collapse of the superficial
flap over the TrabeculoDescemet’s membrane and
the remaining very thin
scleral bed, an implant is
placed in the scleral bed.
 Implants Porcine collagen,
 Reticulated hyaluronic acid
 HEMA
Implant sutured onto
the scleral bed
 Two interrupted 10-0
nylon sutures are
used to suture the the
scleral flap.
 The conjunctiva is
closed with wet field
cautery.
VISCOCANALOSTOMY
 Fornix or limbal based
conjunctival flap.
 Superficial scleral flap - 5
x 5 mm ,1/3 of the scleral
thickness (300 microns).
 In order to be able to
dissect down to
Descemet’s membrane
later, the scleral flap is
dissected 1 to 1.5 mm
into clear cornea
 A deep scleral flap is
then dissected to 95%
of remaining
thickness of the
sclera
 Schlemm’s canal is
unroofed at the level
of the scleral spur to
expose the TM.
Superficial
Scleral Flap
Deep
Scleral
Flap
 A finely polished
cannula with an outer
diameter of 150 µm is
introduced into and a
Schlemm's canal, and
a high-viscosity
viscoelastic (Healon
GV) is injected 4.0 to
6.0 mm on each side.
Dilated cut ends of Schlemm’s Canal after Visco injection
 The viscoelastic injection increases the diameter of
Schlemm's canal from its usual diameter of 25 to 30 µm
to about 230 µm and increases the patency of the
outflow channels
 Aqueous is removed by a paracentesis to prevent
rupture of TDM.
 Descemet's
membrane is
separated 1 to 2 mm
from the
corneoscleral junction
by applying gentle
pressure on
Schwalbe's line using
a cellulose sponge.
 This creates an intact window in Descemet's membrane
through which aqueous humor diffuses from the anterior
chamber into the subscleral lake bypassing the inner
wall (floor) of Schlemm's canal.
 The deep scleral flap is then excised at its base
 The superficial flap is sutured using five 11-0 nylon
suture in a watertight manner
 Viscoelastic is subsequently injected into the subscleral
lake.
 The conjunctival flap is closed with sutures.
LASER TRABECULAR ABLATION
 Topical anesthesia
 fornix based
conjunctival flap
 A circle straddling the
limbus marked with
the help of a 4.25 mm
optic zone marker
 A corneo scleral
incision with a
diamond knife
calibrated at 350
microns.
 The flap is dissected
and bent forward over
the clear cornea to
expose the area that
will be treated
Reflected scleral flap
 A specially designed
mask with a 2 x 4 mm
window, is placed to
protect the
surrounding tissue
from the excimer rays
Mask with 2x4mm window
 The ablation of the deep scleral wall is made
using PTK software that removes successive
layers of 0.25 to 2 microns
 Ablation proceeds in the following orderDeep sclero- corneal tissue
Roof of Schlemms canal
 Part of its internal wall
Adjacent corneal stroma 1 millimeter in front of the
Schlemm’s canal
 Ablation is continued up to the moment when a
drop of aqueous humor appears
CANALOPLASTY
360 degree viscodilatation of Schlemm’s
canal with an illuminated beacon tipped
microcatheter.
Diameter of the microcatheter -200µ
A 10-0 prolene suture is also passed
through the entire Schlemm’s canal and
tightened towards the AC-Produces a
further 2-3mm fall in IOP.
COMPLICATIONS
 1)Moderate transient hypotony in the first postoperative week.
 2)High IOP on 1st post op day-Due to
insufficient dissection of the TDM.Treated with
Nd:YAG goniopuncture.
 3)Rupture of the TDM postoperatively-Due to
vigorous eye rubbing,valsalva.Due to rupture of
the TDM,iris prolapse occurs and blocks the
filtration site causing elevation of IOP .
Treatment-revision of the filtration site and
conversion into a conventional trabeculectomy
4)PAS at filtration site-Treated with YAG
iridoplasty
5)Descemets Membrane detachment-Rare
complication. More common with
Viscocanalostomy.Usually
transient.Severe cases, Descemets
Membrane reposition maybe necessary.
6)Scleral ectasia-Rare complication
RESULTS
 Deep Sclerectomy provides much better results when
performed using implants or antimetabolites or both.
 Viscocanalostomy shows the same results with or
without implants and antimetabolites
 When the above were compared with
trabeculectomy,72% of patients who underwent trab.
With antimetabolite achieved a target IOP of <21mmHg
.51% of patients who had deep Sclerectomy with implant
and 34% of patients who underwent Viscocanalosiomy
with antimetabolite achieved a target IOP <21mmHg .