Glaucoma Drainage Devices

1. GLAUCOMA DRAINGE-
DEVICE SURGERY
Dr. Nilay Patel
Dept of Ophthalmology
Dr. D .Y. Patil University,School of Medicine

2. Physiology of Drainage Implants
• A silicone tube that extends from the AC to a plate, disc, or encircling
element beneath the conjunctiva and tenon capsule. External plate has a
ridge through which the tube enters on to its surface.The ridge decreases
the risk of obstruction with the surrounding tissue and fibrous capsule and
forms a filtering bleb posteriorly near the equator.
• A fibrous capsule forms a filtering bleb around the external portion of the
draining device.
• After insertion, a thin collagenous capsule, surrounded by granulomatous
reaction is present which subsides after 4 months.The capsule thickness
remains stable and collagen stroma becomes less compact.
• There is a direct relation between surface area of the implants and the
filtering capacity of their surrounding capsule.
• Reduction in bleb diameter decreases surface tension, capsular fibrosis and
thickness thus increasing the effectiveness of the filtering surface.

3. • All drainage devices develop an elevated IOP weeks to months after
implantation due to capsule formation.This is termed as Hypertensive Phase
The indications for GDD implantation include the following:
• Neovascular glaucoma
• PKP with glaucoma
• Retinal detachment surgery with glaucoma
• ICE syndrome
• Traumatic glaucoma
• Uveitic glaucoma
• Open-angle glaucoma with failed trabeculectomy
• Epithelial downgrowth
• Refractory infantile glaucoma
• Contact lens wearers who need glaucoma filtration surgery

4. Implant designs:
A) Open-Tube Drainage Devices
-Baerveldt Implant:a) 250 mm2 area
b) 350 mm2 area
c) 500 mm2 area
d) 35o mm2 area pars plana
-Molteno Implant
-SchocketTube Shunt
B) Flow Restricted/Valved Devices
-Ahmed GlaucomaValve
-Krupin Implants.
C) Newer Devices
-iStent
-Ex-PRESS Device
-SolxGold Shunt
-OptiMed glaucoma Pressure
Regulator
-SusannaGlaucoma Implant

5. A) Baerveldt Implant:
-Non valved drainage implant.
-Designed for single quadrant conjunctival insertion.
-Material: Medical grade silicon plate (soft barium impregnated
silicon plate) with a silicon tubing.
-Size: Plate surface area a) 250 mm2 (20 x 13 mm)
b) 350 mm2 (32 x 14 mm)
c) 500 mm2
-Position: Under the rectus muscle insertion usually in the
superotemporal quadrant.
-Features: 4 fenestrastions that allow growth of fibrous tissue through
the plate, serving to reduce the height of the BLEB thus reducing
the risk of dislocation of the implant and diplopia.
3-4 weeks post op fibrous capsule forms over the implant,
therefore full efficacy of the implant is achieved after that.
Open drainage devices

6. -Complications:
a)Suprachoroidal haemorrhage
b)Aqueous misdirection
c)Choroidal effusion
d)Tube blockage
e)Tube migration
f)Implant migration
g)Corneal ulcer , hyphema and endophthalmitis.

9. B) Molteno Implant:
-Non valved drainage implant introduced in 1969.
-Original design had a single plate ( 13 mm diameter and 135mm2
surface area ).To increase the efficacy second plate was added.
3Rd generation plate was developed, it has a bowl shaped
structure ( it is designed to function as a biological valve by l
imiting the available area of filtration during times of low
aqueous production.)
-Material:Acrylic plate with silicon tubing
-Size: Surface area of single plate is 135mm2 and 13 mm diameter
Double plate is 270 mm2 , 175 mm2 and 230 mm2.
Silicon tubing had an external diameter of 0.62mm and internal
diameter of 0.30mm.
-Position: Under the rectus muscle insertion usually in the
superotemporal quadrant.
-Features:V-shaped pressure ridge on the upper surface encases
10.5mm2 around the tube opening to deal with the problem of
Hypotony and excessive filtration in post op period.

12. C) SchocketTube Shunt:
-Non valved drainage implant.
-A Silicon or Silastic tube is extended from the AC to a 360 degree
encircling silicon band which functioned in developing the
reservoir for aqueous drainage.
-Material: Silicon or Silastic tubing.
-Position: 90 degree insertion of the silicon tube originating from
the AC to the encircling band beneath 2 or more rectus muscles
-Features: Its provides a larger surface area of reservoir compared
to molteno implant.
-Procedure: A 30-mm long silastic lacrimal tube with an internal
diameter of 0.30 mm is sutured inside the groove of a #20 silicone band,
leaving 15 mm of the tube extending from the band.The encircling band
is circumferentially sutured to the sclera, 10–12 mm from the limbus
beneath the four rectus muscles, with 5-0 Supramid sutures.A square 3–
4mm scleral flap hinged at the limbus is elevated, and a slightly beveled
puncture wound is made into the anterior chamber.The end of the tube is
beveled and inserted into the anterior cham- ber so that a 3-mm length is
suspended between the iris and cor- nea with the bevel facing anteriorly.
The scleral flap is closed with 10-0 nylon, and the conjunctival flap is
sutured with 8-0Vicryl.

14. Flow restricted /Valved Devices:
A) Ahmed GlaucomaValve (AGV) implant
-Valved implant design
-Design and material: Silicone tube is connected to a silicone sheath
valve held in a polypropylene / silicone body.
For pars plana insertion , a pars plana clip can be used .
-Models: most commonly used model is S2 ,
flexible siliconeAGV FP7 (0.9 mm thick).
Adult and pediatic (96 mm2 surface area)AGV are also available.
-Valve mechanism:
-2 thin silicone elastomer membranes , 8 mm long and 7 mm
wide I is used which allows 1-way regulation.
-Inlet cross section is wider than the outlet , so small pressure
differentials between the AC and the subconj space , enabling
the valve to function even at small pressure differences.
8 to 10 mmHg in early post op period

15. -Venturi effect of the valve can be explained by Bernoulli’s equation of fluid
dynamics.
( flow rate of a fluid is inversely proportional to the pressure of the fluid)
-The aqueous humor flows slowly into the trapezoid chamber and increases
the pressure.On reaching the pre-set threshold value , the valve opens thus
decreasing the pressure.
-The fluid velocity has to increase as it leaves the chamber (due to rise in
pressure) through the drainage tube .The tension in the silicone membranes
helps reduce hypotony as the valves closes as pressure decreases.
-No-touch zone on the AVG is area of the chamber with silicone leaflets.
If the implant is grasped with the forceps along the centre line, it may separate
the valve cover from the implant leading to failure due to adhesion of the valve
membrane.

17. Ahmed GlaucomaValve

18. B) Krupin Implants
-Valved implant with multiple leaflets.
-The original design of krupin was without a disc , similar to
Schocket type of implant.
-Present design consists of the krupin valve with a disc, a silastic
tube is attached to an oval silastic disc, conformed to the curvature
of the globe (360 degrees), 13mm x 18mm , with side walls 1.75
mm high.
-The valves are designed to open at pressures of 10 to 12 mmHg.
Valve lies on the inside of the rim and comes in direct contact with
the subconj tissue.
-Designed to reduce post op hypotony and excessive drainage.

19. Newer Setons:
1) Glaukos iStent
-Light weightTitanium L-shaped device placed inside the
schlemm’s canal, to allow aqueous to bypass the inner wall
of schlemm’s canal and the juxtacanalicularTM
-1mm of the device sits in the SC and is shaped like a half
pipe.
-Small snorkel shaped tube 0.5 mm size sits in the peripheral
AC
-The device is designed to fit into the schlemm’s canal,
-The implant is heparin covered for thrombolytic activity and
prevent stenosis.
-The 3 barbed ridges are designed to prevent loosening and
secure placement.
-The device is placed in the nasal quadrant under
gonioscopic
guidance.

20. iStent

21. 2) Ex-PRESS mini shunt:
- 400 micron wide x 3 mm long , stainless steel device.
- It has a beveled sharpened rounded tip, disclike flange (<1 mm2) at the
proximal end and a spurlike projection that prevents its extrusion.
- Thickness corresponds to the scleral thickness, the external flange and
the inner spur are angled to conform to the scleral anatomy.
- Inner diameter is 125 microns and outer diameter is 250 micron, thin
enough to fit into the scleral spur.
- Sterilization: by gamma radiation , stored at 15-30 degree C
- Immediate bleb formation on 1st or 2nd post op day.

22. Ex-PRESS mini shunt

23. 3) Gold Micro-Shunt
- Deep Light Glaucoma tx:Titanium sapphire laser and photo titratable gold
micro shunt
- Laser emits microsecond infra red light pulses that passes through the
trabecular meshwork tissues to produce an opening for outflow.
- The 99.5% inert gold shunt is placed which have micro channels , which can
also be titrated post op using titanium sapphire laser.
- The biocompatible gold plate is 5.2 mm long, 2 mm wide and 60 micron thick
containing multiple microchannels
- It is implanted through a 3 mm clear corneal incision with a help of a pre
loaded injector.
- Thus the channels of the gold shunt form a bridge b/w AC and suprachoroidal
space.

24. 4) OptiMed glaucoma Pressure Regulator:
- Silicon tube with a PMMA plate.
- Inner diameter of the tube is 0.38 mm and outer diameter is 0.76 mm.
- 5 mm PMMA tube is inserted into the silicone base with dimensions of
1 x 2 x 3 x 4 mm , base contains 180 to 200 microtubules.
- It functions when the pressure exceeds 10 mmHg , through the capillary
action, it works on the principle of Poiseuille’s formula.

25. 5) Susanna Glaucoma Implant:
- A reservior body conforming to the shape of the globe at its equator and a
ridge in the end plate to protect the inner opening of the silicone tube from
blockage by fibrous tissue growth.
- Fenestrating end plate promotes fibrous tissue anchoring.(to avoid motion)
- The footplate measures 4 mm length allow easy fixation at 6 mm from the
limbus and yet allowing the plate to be placed at 10 mm from the limbus ( to
reduce extrusion)

26. COMPLICATIONS:
a) Intraoperative complications:
• Bleeding
• Misdirection of the silicone tube into the posterior chamber in
presence of peripheral anterior synechiae
• Loss ofAC: if port size is large
b) Early Post operative complication:
• Hypotony: maybe asso with Choroidal effusions.
use of valved implants or by occluding the tubing with a ligature
• Increased IOP: due to occlusion , with iris ,YAG ablation of the iris
• Tube-corneal contact: avoided by placing the tube properly
intraoperatively
• Early post op endophthalmitis

27. c) Late complications:
• Encysted bleb: in the hypertensive phase rise in IOP due to
development of a thick capsule around the plate 4 to 6 weeks postop
regimen consists of Diclofenac 75 mg , prednisolone 40 mg and
topical steroids.
1 cm3 can be deflated by needling
• Erosion of the silicon tube.
• Plate migration
• Eye movement limitations
• Endophthalmitis
• Epithelial ingrowth and invasion into the fibrous capsule
• Sterile hypopyon
• Irregular pupil due to adhesions of the iris roots
• Globe perforation
• RD, supra choroidal h’age,VH, choroidal effusion.

29. Hyphema: POD 4 and POD 35
Hypotony POD 3
Hypotony with choroidal effusion

35. THANK YOU