Pearls about trabeculectomy surgery

1. TRABECULECTOMY:
Surgical Procedure
Presenter: Dr. Iddi Ndyabawe
Supervisor: Dr Otiti Juliet Sengeri
Date: 12/10/2020

2. OUTLINE
• Introduction to filtration surgeries
• Trabeculectomy: Stand-alone technique; a step by step approach
• Flap management
• Combined cataract surgery and trabeculectomy
• Tube shunt implantation
• Summary

3. INTRODUCTION
• Surgical treatment for glaucoma is usually undertaken when medical therapy is not appropriate, not
tolerated, not effective, or not properly used by a particular patient, and the glaucoma remains
uncontrolled with either documented progressive damage or a high risk of further damage. (5)
• Surgery encompasses both laser and incisional procedures.
• Laser surgery is used as primary, adjunctive, or prophylactic treatment in various types of glaucoma.

4. INCISION SURGERY
• Frequently used for chronic forms of glaucoma in adults –
• External filtration:
• • Full thickness(Scheie) procedures: Thermal sclerostomy, sclerectomy, Elliott’s trephination
• • Guarded procedures: Trabeculectomy
• Internal filtration:
• • Cyclodialysis
• Trabecular meshwork disruption:
• • Trabeculotomy ab externo
• • Goniotomy

5. Trabeculectomy
• Definition: Trabeculectomy is a guarded partial-thickness fistulizing procedure in which a block
of peripheral corneoscleral tissue is removed beneath a scleral flap.
• Intent is to bypass the eye’s natural outflow pathway of aqueous.
• Dynamics: allows aqueous humor to flow out of the anterior chamber via a surgical corneoscleral
opening & into the sub-conjunctival and the sub-Tenon space.
• Trabeculectomy is the most effective glaucoma surgery in terms of intraocular pressure reduction. (M.
Reza, 2011). Labeled as “Gold standard” and has stood the test of time the longest!!! (Koike et al, 2018)
• History: Initially described by Cairns in 1968 and later modified by Watson in 1970. (Koike et al, 2018)

7. INDICATIONS OF
TRABECULECTOMY
• The main indications for surgery are progression of visual field damage and
uncontrolled IOP.
• But; in many cases, the decision to proceed with surgery is made even in the absence
of documented progression and is based on a clinical judgment that the IOP is
too high for the stage of the disease.
• GLAUCOMA IN AN “ONLY EYE”

8. .
• Intraocular pressure too high to prevent future glaucoma damage and
functional visual loss
• Documented progression of glaucoma damage at current level of intraocular
pressure with treatment
• Presumed rapid rate of progression of glaucoma damage without
intervention
• Poor compliance with medical therapy : cost, inconvenience, understanding
of disease
• Intolerance to medical therapy due to side effects

9. REASONS FOR UNCONTROLLED
GLAUCOMA
• Maximally tolerated medical therapy and laser surgery (trabeculoplasty,
iridotomy, and/or iridoplasty/gonioplasty, when indicated) fail to adequately
reduce IOP.
• Glaucomatous optic neuropathy or visual field loss is progressing despite
apparent “adequate” reduction of IOP with medical therapy (with or without
laser surgery).
• The patient cannot adhere to the necessary medical regimen: SE, costs,
inconvenience,

10. CONTRAINDICATIONS
• Absolute: Blind eye or poor visual potential
• Relative:
• Anterior uveitis Rubeosis iridis, Uveitic glaucoma, Neovascular glaucoma, Conjuctival
scaring/injury, Scleral thinning, Necrotising scleritis, Previously failed trabeculectomy
• Aphakic or pseudophakic after MSICS through scleral tunnel incision
• Black patients have a higher failure rate with filtering surgery.

11. Preoperative evaluation
• Consider patient’s general health, presumed life expectancy and status of the fellow eye.
• Control of preoperative inflammation with corticosteroids helps reduce postoperative anterior uveitis and
scarring of the filtering bleb.
• Blepharitis & allergic conjunctivitis should be controlled preoperatively.
• Before surgery, the IOP should be reduced as closely as possible to normal levels in order to minimize the risk
of expulsive choroidal hemorrhage.
• If possible discontinue antiplatelet and anticoagulant medications in consultation with the patient’s primary
care physician.
• Systemic hypertension should be controlled.
• Take informed consent and explaining the purpose of and expectations for the surgery.

12. Preoperative examination
• 1. Note ocular motility, status, and mobility of the conjunctiva, presence of
ocular surface disease, and health of the sclera at the anticipated surgical site.
• 2. Perform gonioscopy; look for peripheral anterior synechiae near the
planned opening of the internal ostium of the sclerostomy
• LABEL THE EYE TO BE WORKED ON!!!

13. INSTRUMENTS AND SUPPLIES
• • lidocaine 1%, bupivacaine 0.5%, or tetracaine 0.5%
• • ophthalmic viscosurgical device (OVD) (optional)
• • 7-0 or 8-0 polyglactin and/or 10-0 nylon suture with cutting /tapered needles
• • 0.12-mm toothed forceps
• • serrated tissue forceps
• • 15° microsurgical blade
• • blunt Westcott scissors
• • Vannas scissors
• • No. 57 Beaver or similar blade
• • eraser- tip microcautery unit
• • Tooke knife
• • Kelly- Descemet punch
• • needle holder
• • tying forceps
• • balanced salt solution (BSS)
• • ophthalmic sponges (eg, Merocel)
• • 3.0- mL syringe with 30- gauge cannula
• • antifibrotic agent options: mitomycin C 0.2–0.5 mg/mL or 50 mg/mL 5- fluorouracil

14. STEPS IN TRABECULECTOMY
• Anaesthesia
• Preparation of surgical site
• Exposure
• Conjuctival incision
• Hemostasis
• MMC or 5-FU application. Then wash it away with BSS
• Scleral flap
• Paracentesis
• Sclerostomy
• Iridectomy
• Closure of scleral flap
• Flow adjustment
• Closure of conjuctiva

15. Traction sutures
• Superior rectus traction (or bridle) suture
• Complications: subconjunctival hemorrhage, conjunctival defects, scleral perforation
postoperative ptosis

16. Traction sutures
• Clear Corneal traction sutures: A 7-0 polyglactin (vicryl) suture is passed through
approx. ¾ th thickness of superior peripheral cornea (4-5 mm width) 1mm form
limbus
• Complication: •May distort the cornea and anterior chamber during surgery

17. T r a b e c u l e c t o m y
T e c h n i q u e
Fornix-based flap
Limbal-based flap

18. Trabeculectomy Technique
L i m b a l - b a s e d fl a p Fornix-based flap
Difficult for beginners & patients with deep orbits Easier to create
More difficult dissection & exposure
Easier exposure & dissection of the sclera
Less diffuse bleb when compared to the fornix based bleb.
Due to sub conj scar posterior to scleral flap Disadv
Creates a more posterior diffuse bleb. Adv. Due to subconj
scar anterior to scleral falp
Better water-tight closure. Less post op incision leakage Adv May be more prone to leaks if not closed properly. Disadv

19. Antifibrotic a gents
• The application of antifibrotic agents such as 5-FU and MMC results in lower IOP following
trabeculectomy.
• However, the rate of serious postoperative complications may be higher, and these agents must not be
used indiscriminately.
• Because their use is associated with an increased risk of hypotony maculopathy, antifibrotic agents should
be used with caution in primary trabeculectomies on young patients with myopia.
• Mitomycin-C 2mg/ vial – Concentration:
• 0.25 to 0.5 mg/ml –
• Duration 1 to 5 minutes – Concentration & duration is dependent on the appearance of the conjunctiva & presence of
risk factors for failure.
 5-Fluorouracil 250mg/ml
• Intra-op: 0.5ml (25mg) to 1ml (50mg) for 5 mins.
• Post-op: 0.1ml (5mg) subconjunctival injection daily for 7-14 days (Total dose not to exceed 50mg or 1ml.)

20. Delivering the anti-fibrotic agent
• Cellulose sponge ̴5 × 3 mm soaked in antimetabolite is placed under
dissected tenon’s capsule for 5 mins before paracentesis of AC followed by
thorough irrigation with BSS

21. RING OF STEEL
Cover largest area possible for more diffuse noncystic bleb
and prevent posterior limiting scar (‘ring of steel’)

22. Complications of antimetabolites
• Corneal epithelial defects
• • Post-operative wound leaks
• • Cystic thin walled bleb: Chronic hypotony, late-onset bleb leak,
endophthalmitis

23. Moorfields Eye Hospital (More Flow) intraoperative Single Dose Anti- Scarring
Regimen 2006
Low Risk Patients (Nothing or intra-operative 5-FU 50mg/ml)
• No risk factors
• Topical medications (beta-blockers/pilocarpine)
• Afro-Caribean
• Youth <40 with no other risk factors

24. .
Intermediate risk patients (intraoperative 5-FU 50mg/ml or MMC 0.2
mg/ml)
• Topical medications (adrenaline)
• Previous cataract surgery without conjunctival incision
• Combined glaucoma filtration surgery/cataract extraction
• Previous conjunctival surgery eg. Squint surgery/ detachment surgery/
trabeculotomy

25. .
High risk patients (Intra operative MMC 0.5 mg/ml)
• Neovascular glaucoma
• Chronic persistent Uveitis
• Previous failed trabeculectomy/tubes
• Chronic conjunctival inflammation
• Secondary glaucomas: inflammatory, post-traumatic angle recession,
iridocorneal endothelial syndrome
• • Aphakic glaucoma

26. SCLERAL FLAP
1.The scleral flap and its relationship to the
underlying sclerostomy provide resistance to
outflow
2. 3- to 4-mm triangular, trapezoidal, or
rectangular flap.
3.Tools: 57 blade or crescent blade

27. • .

28. .
• A temporal paracentesis is created
through clear cornea, radial to the limbus.
• Tool: 15 blade… To enable the surgeon to
control the anterior chamber
• This allows instillation of balanced salt
solution (BSS) or viscoelastic and
intraoperative testing of the patency of the
filtration site.
• BSS is instilled through the paracentesis, and
sutures are added to the scleral flap until
flow is minimal.
• Using the existing paracentesis is much safer
than trying to create a paracentesis in an eye
with a flat chamber

29. Sclerostomy
• .

30. I r i d e c t o m y
1. An iridectomy is performed to reduce the risk of iris occluding the sclerostomy, especially in phakic and narrow-
angle eyes, and to prevent pupillary block.
2. An iridectomy may not always be necessary in pseudophakic eyes with deep anterior chambers or if a titanium
shunt is inserted under the flap
3. Care should be taken to avoid amputation of the ciliary processes or disruption of the zonular fibers or hyaloid
face. Complications: Hyphaema, inflammations, iridodialysis

31. C L O S U R E O F S C L E R A L F L A P
There are two methods for closing the scleral flap
 Releasable flap Sutures
 Tight suture which are removed afterwards with laser ( suture lysis).

32. Scleral flap pearls
• Place sutures anteriorly along each side of the scleral flap to direct aqueous posteriorly. In
addition, this approach prevents conjunctival wound leaks with fornix- based conjunctival
incisions. (one suture can suffice at apex if triangular flap done: 3-1-1 technique)
• Apply scleral flap sutures 1–2 mm from each side of the scleral flap. This allows easy access
to the sutures for postoperative laser suture lysis. Sutures should simply oppose the scleral
flap edges to the flap bed. If sutures are placed too tightly, significant postoperative
astigmatism may be induced.
• Additional scleral flap sutures may be necessary to prevent shallow anterior chambers in
select cases, prevent postoperative hypotony maculopathy in highly myopic eyes, and reduce
the risk of developing postoperative ciliary block glaucoma in eyes with angle- closure
glaucomas.
• Injecting BSS through the side- port incision into the anterior chamber assists in
testing the scleral flap for adequate resistance to aqueous outflow.
• If the conjunctiva is thick or a surgeon does not have postoperative access to a laser,
releasable 10-0 nylon sutures may be used to close to the scleral flap and allow for
titration of postoperative IOPs

33. Closure of scleral Flap

34. LASER SUTURE LY SIS
• Conjunctiva is compressed with either a Zeiss goniolens or a lens designed for suture lysis.
• The argon green laser (set at 240–600 mW at a duration of 0.02–0.1 second with a spot size of 50–
100 μm) or red laser can usually lyse the selected black 10-0 nylon suture with one application.
• It is important to avoid creating a full-thickness conjunctival burn.
• Shorter duration of laser energy and avoidance of pigment or blood are helpful for preventing such a
burn.
• Most surgeons wait at least 48 hours before performing LSL.
• Filtration is best enhanced if lysis or suture release is completed within 2–4 weeks of the surgery or
before the occurrence of ap fibrosis.
• This period may be lengthened to several months when antifibrotic agents have been used.

37. CLOSURE OF CONJUNCTIVA
 Many techniques developed for conjunctival closure.
 It is important that the closure be watertight at the completion of the procedure.
 For a fornix-based flap, conjunctiva is secured at the limbus.
 Several techniques are used for this closure, including episcleral-anchored interrupted sutures at
each end of the incision; a running mattress suture; and purse-string closures at each end of the
incision, with or without mattress sutures in between.
 For a limbus-based flap, conjunctiva and Tenon capsule are closed separately or in a single layer with a
running suture of 9-0 nylon or polyglactin 910 on a vascular needle, which minimizes wound leak in
procedures where MMC has been applied

38. C ombined C a ta ra ct a nd
Trabeculectomy
• Both cataract and glaucoma are conditions that are more prevalent with age.
• It should also be noted that cataract surgery alone may lower IOP in eyes with open angles and may lower it even more in
eyes with phacomorphic narrow angles.
• A combined procedure (cataract extraction plus trabeculectomy) may prevent a postoperative rise in IOP.
• Combined procedures are generally less effective than trabeculectomy alone in controlling IOP over time because
the inflammation induced by cataract surgery increases the risk of bleb failure.
• For patients in whom glaucoma is the greatest immediate threat to vision, trabeculectomy alone is usually performed first.
• Several clinical challenges are common in patients with coexisting cataract and glaucoma.
• Medical therapy for glaucoma may create chronic miosis, and the surgeon must deal with a small pupil; A/C shallow in
angle closure, weak zonules in PXF, vitreous loss more common in complicated eyes

39. Indications
• Cataract surgery may be combined with trabeculectomy in the following situations:
1. cataract requiring extraction in a glaucoma patient who has advanced cupping and visual field loss to
minimize postoperative pressure spike
2. cataract requiring extraction in a glaucoma patient who requires medications to control IOP but who
tolerates medical therapy poorly or has inadequately controlled IOP
3. cataract requiring extraction in a glaucoma patient who requires multiple medications to control IOP

40. Relative contraindications
• Combined cataract and filtering surgery should be avoided in the following situations, in
which glaucoma surgery alone is preferred:
• Glaucoma that requires a very low target IOP
• Advanced glaucoma with uncontrolled IOP and immediate need for successful reduction of IOP

41. Tube Shunt Implantation
• There are many different types of devices that aid angle filtration by shunting aqueous to a site away
from the limbus, such as the equatorial subconjunctiva
• Tube shunts can be broadly categorized as non-valved devices, which have no flow restrictor, or valved
devices, which have a flow restrictor.
• The most frequently used non-valved devices are:
• Molteno
• Baerveldt
 The most widely used valved device is the Ahmed design

44. Indications
• Failed trabeculectomy with antifibrotics
• Active uveitis
• Neovascular glaucoma
• Inadequate conjunctiva
• Aphakia
• Contact lens use

45. Contraindications
• Tube shunts may have a complicated postoperative course.
• Borderline corneal endothelial function is a relative contraindication for
anterior chamber placement of a tube.

46. NO N - PENETRA TING GL AUC OMA
SURGERY
• In non-penetrating filtration surgery the anterior chamber is not entered and the internal
trabecular meshwork is preserved, thus reducing the incidence of postoperative overfiltration
with hypotony and its potential sequelae.
• These are:
1. Deep sclerectomy
2. Viscocanalostomy
3. Canaloplasty
4. Trabectome.

47. SUMMARY
• Incisional surgeries can generate very low IOPs.
• Antimetabolites increases the success rate but also they have their own complications.
• MIGS are now becoming more popular but still incisional surgeries still have a role.

48. THANK YOU