Surgical Management of Glaucoma-Elias.pptx

Surgical Management of Glaucoma
Elias T(Ophthalmologist,MD)

outlines
• Introduction
• Overview of types of glaucoma surgery
• Trabeculectomy
• Aqueous drainage device
• Angle Surgery
• Non penetrating Surgery
• MIGS
• Combined Cataract and Glaucoma Surgery
2/4/2024 Glaucoma Surgeries - EliasT 2

Introduction
• Glaucoma refers to a group of progressive optic neuropathies characterized by an
• Excavated appearance of the optic disc, often described as cupped
• Loss of retinal ganglion cells and their axons and corresponding vision loss
• Eventual development of distinctive patterns of visual dysfunction (VF)
• Causes of glaucoma are multifactorial and include genetic and environmental
• IOP is a continuous risk factor for the development of glaucoma over its entire
range
• By 2020 - 80 million people worldwide will have glaucoma
• 11.2 million bilaterally blind as a result

…cont.
• Factors that determine the IOP
• The rate of aqueous humor production
• The rate of drainage
• The level of episcleral venous pressure

Anatomical principle of glaucoma surgery

Glaucoma Surgery
Usually undertaken when medical therapy is
• Not appropriate
• Not tolerated
• Not effective
• Not properly utilized by particular patient
• If medical therapy is failed (uncontrolled IOP or documented progression)
• As primary approach for both congenital glaucoma and pupillary block glaucoma

How to reduce IOP
Enhance Outflow
• Physiological pathways:
• Trabecular meshwork- trabectome
• Schlemm’s canal – istent, ipass, icath
• Suprachoroidal space - Gold shunt
Subconjunctival drainage:
• Trabeculectomy
• Non-penetrating surgery
• Aqueous drainage device
Reduce inflow:
• Endoscopic cyclophotocoagulation

…cont.

…cont.
• Patient Selection
• History
• Physical Examination
• Laboratory Investigation

Chart flow

Trabeculectomy
• Is an incisional procedure
• Fistula is created between the anterior chamber and the subconjunctival space
• By passing the normal aqueous outflow pathway
• Protected by a superficial scleral flap

Indications
Considered when surgical risks are outweighed by the potential benefits
• Failure of conservative therapy
• Optic nerve function is failing or is likely to fail
• Progressive VFL
• Progressive deterioration despite seemingly adequate IOP control
• Primary therapy
• Significant barriers to using medications regularly
• Patient preference

Contraindications
• Blind eye
• Conjunctival scar, thin sclera
• Active anterior segment neovascularization (rubeosis iridis)
• Active iritis

Preoperative Evaluation
• Patient’s general health
• Control inflammation, IOP & ocular surface infection
• Review medication
• Informing patient on purpose of and expectations about the procedure

…cont.
Pre operatively, pt should understand
• Surgery alone rarely improves vision
• Surgery may fail completely
• Could lose vision as a result of surgery
• Glaucoma may progress despite successful surgery

Basic techniques of filtering surgery
Exposure
• Traction suture for good surgical exposure
• Superior rectus traction suture- uses 4-0 silk
• Clear corneal traction suture- uses 7-0 polyglactin or silk
• 3/4th corneal thickness, 1mm from limbus, width of 4-5mm
• Better over SR traction suture

...cont.

Conjunctival incision
• Is a critical step in all filtering procedures
• Most common cause of failure is scarring of filtering bleb
• 12-o’oclock/ one of superior quadrant position is preferred.
• Need to minimize tissue damage & bleeding.
• Limbus based vs fornix based.
• Recently fornix based flap favored, have similar success rates

FBCF Vs LBCF

Management of tenon capsule
• Is main source of fibroblast in area of conj. flap
• Controversy regarding removal of all or a portion
• But better to leave if anti fibrosis used

Antemetabolites
• used for reduction of fibrosis
• Placed under scleral flap and conj pockets

Complications of anti-metabolites
• Thin avascular cystic bleb
• Hypotony
• Endothelial damage and ciliary body destruction
• Infections: blebitis, Endophthalmitis
• Scleritis, scleromalacia and necrosis
• ?? Mention or discuss complications specific to specific
antimetabolites

Scleral flap
• First cauterize adjacent to corneo limbal junction
• Partial thickness 3-4mm scleral incision(1/2-2/3 depth)
• Lamellar flap at limbus is dissected forward, 1mm cornea
• Can have d/t shapes
• Square, traingular, semicircular, or trapezoid shape

Paracentesis
• Should precede sclerostomy
• Done with tapered pointed knife or 75 blade
• Use of VED
• Avoiding intraoperative hypotony → decrease suprachoroidal effusion- no
shallow AC
• Minimize intraoperative bleeding
• Temporary solution for postoperative flat anterior chambers
• Draw back
• Higher early postoperative IOP
• Iris prolapse during surgery

keratectomy
• Removing a block of peripheral cornea(0.75–1mm)
• Means of fistulizing
• Commonly created with the use of a punch
• PI: To reduce the risk of iris occluding the sclerostomy
• Complication: amputation of ciliary processes or disruption of zonular fibers

Closing sclera and conjunctiva
Flap closure
• Fixed, interrupted sutures
• Adjustable sutures
• Releasable sutures
Closure of conjunctiva:
• Test the scleral flap integrity before closing the conjunctiva.
• Many techniques have been developed for conjunctival closure
• Limbus based flap
• Fornix based

Post op care
• Follow up closely-50% surgery +50% post op care
• Topical corticosteroids
• Topical antibiotics
• Cycloplegic agents- prevent AC shallowing
• Oral or IV steroid for uveitic glaucoma
• IOP monitoring
• Ocular Exam

Bleb configuration
MaBAGS

MBGS

Cont.…
Indiana Bleb Appearance Grading Scale
IBAGS

Complication

…cont.

Hypotony
• Ocular hypotony is an uncommon but potentially vision-threatening event
• Either an IOP that is 3 standard deviations below normal (<6.5 mm Hg)
• An IOP low enough to cause visual impairment
• Manifests in the form of hypotony maculopathy, corneal edema, astigmatism,
choroidal effusion
Possible causes
• Conjunctival defect (Bleb leak)
• Overfit ration
• Cyclodialysis cleft
• Ciliochoroidal detachment
• Inflammation
• Can be with shallow/flat AC or deep AC.

Hypotony …

Pressure patch

…

Elevated IOP with shallow AC

Elevated IOP with deep AC
• Inadequate filtration
• Localized:
• Tenon cyst (encapsulated cyst)
• Diffuse:
• Flap resistance (fail bleb)

Wipe-out or snuff syndrome
• Severe visual loss after surgery, with no obvious cause
• Common in
• Advanced glaucoma (Advanced visual field defects affecting the central field )
• Older patients with high preoperative IOP
• Postoperative complications
Mechanism
• Damage to ON due to anesthesia
• IOP spikes
• Decreased blood flow to ON
• Post op. hypotony

Bleb related complications
• Bleb leak
• Encapsulated bleb
• Bleb related infection (BRI) - Blebitis and Endophthalmitis
Stage of BRI

Trab failure
Risk factors
• Chronic ocular surface inflammation
• Previous conj. surgery
• Aphakia
• Neovascularization, epithelial down
growth
• West Africa descent, young & male pts
• Conjunctival scarring
Signs of Trab failure
• Reduced bleb height
• Increased bleb-wall thickness
• Vascularization of bleb
• Loss of conjunctival microcysts
• Increased IOP

Management of trab failure

Ex-Press™ mini-shunt
• Valveless titanium MRI-compatible stent
• Inserted under a scleral flap during a modified trabeculectomy
• Hypotony and hyphaema is lower than with standard trabeculectomy
• IOP control is equivalent

Plate-Based Tube Shunt Surgery
• Designed to shunt aqueous from the anterior chamber to a subconjunctival space
• Can be divided into valved and nonvalved types
• Valved devices- Flow restrictor
• Ahmed valve, krupin
• Nonvalved devices - No flow restrictor
• Molteno and Baerveldt

…cont.

Indications
• Failed trabeculectomy with antifibrotics
• Active Uveitis
• Secondary glaucoma: neovascular, aniridia
• Severe conjunctival scarring precluding accurate dissection.
• Aphakia
• Contact lens use ????

Surgical Technique
• Exposure
• Conjunctival Incision
• Placement of plate
• Tube placement and management
• Closure

Postoperative management
• Require fewer interventions in the postoperative period compared with trabeculectomy
• In nonvalved devices in which the tube has been occluded, early IOP spikes are best
managed medically
• Releasing the occluding suture after capsule formed in nonvalved devices.
• Topical corticosteroids, antibiotics, and cycloplegics

POP….

Angle Surgery
Goniotomy and Trabeculotomy
• Congenital glaucoma is common indication
Preoperative evaluation
• EUA
• IOP
• Cornea diameter
• OD evaluation
• Pachymetry
• Any secondary cause

Goniotomy
• An incision is made across the TM under direct gonioscopy visualization using a
goniotomy knife
• Allow direct conduit between AC and Schlemm's canal
• The precise mechanism by which pressure reduction occurs remains obscure

Indication
• Primary congenital/infantile open angle glaucoma
• Other primary glaucoma's (generally poor success)
• Axenfeld-Rieger syndrome
• Lowe syndrome
• Neurofibromatosis
• Sturge-Weber syndrome
• Selected secondary glaucoma's
• Maternal rubella syndrome
• Open angle glaucoma soon after congenital cataract surgery
• Uveitic glaucoma (especially with juvenile rheumatoid arthritis)
• Prophylaxis against acquired glaucoma in aniridia*
• Early onset juvenile open angle glaucoma

Complications
• GA related in infant and neonate
• Hemorrhage – incision into anterior CB and sclera
• Cataract – lens injury
• Infection
• Epithelial ingrowth
• Failure – incision anterior to schwalbe line

Trabeculotomy
• Cannulating Schlemm's canal from an external approach and then tearing through
the TM into the AC
• Creates a direct communication b/n AC & SC

Indications
• Same as for goniotomy, (but preferred in the presence of corneal opacification.)
• Performed by some surgeons after two goniotomies have failed
• May be combined with trabeculectomy

Complications
• Hyphema
• Infection
• Lens damage
• Iridodialysis
• Iris prolapse
• Uveitis
• Descemet's membrane may be stripped during trabeculotomy

Non-penetrating surgery
• Enhance natural aqueous outflow channels by reducing outflow resistance
• AC is not entered and the internal TM is preserved
• Two lamellar scleral flaps are fashioned
• Deep flap excised leaving behind thin membrane contain trabeculum/Descemet
membrane
• Aqueous diffuses from AC to subconjunctival space
• Reducing the incidence of postoperative over filtration with hypotony and its
potential sequelae

Cont.…
• Advantages:
• Avoid some of the complications of traditional glaucoma surgery
• Can be considered earlier in the disease process
• Disadvantages:
• Technically challenging
• Lower IOP reduction
• Conjunctival scarring

Deep Sclerectomy
• Partial thickness scleral flap
• Second deep partial thickness scleral flap is fashioned and excised
• Superficial scleral flap is loosely approximated
• Conjunctival incision is closed

Non-penetrating surgery
Viscocanalostomy
• Deep sclerectomy plus viscoelastic substance injection into limited section of
Schlemm's canal
Canaloplasty
• Flexible illuminated catheter is utilized to inject viscoelastic into the full 360° of
the canal and to pass a suture through it.
• The suture is then tied, leaving the canal stretched.

Minimally Invasive Glaucoma Surgery(MIGS)
IOP-lowering surgery with
• Minimally traumatic
• Via an ab-interno conjunctiva-preserving approach
• High safety profile
• Rapid recovery
• Frequently combined with cataract extraction
• Provides more modest IOP lowering than trabeculectomy

Cont.….
MIGS procedures fall into 3 general categories:
• Stents to Schlemm canal
• TM disruption
• Stents to the suprachoroidal space

Cont.….
• Surgery that avoids the formation of a bleb by manipulating the canal of Schlemm
by
• Excision of TM (Trabectome®, Kahook Dual Blade®)
• Bypassing the TM (iStent inject® or Hydrus®)
• Dilation of SC (ab-interno canaloplasty with iTrack®).
• Implants that result in drainage under Tenon capsule and conjunctiva,
• (Xen®, Innfocus Microshunt®) .
• Mitomycin C is usually injected, ↓bleb fibrosis.
• Bleb needling is often required postoperatively

Cont.…

Indications
• Mild to moderate glaucoma where
• The rate of visual field loss is slow
• The target pressure goal is modest (aiming for 15–17 mmHg).
• In selected cases combined with phacoemulsification and IOL implantation
• To reduce the need for topical medication

Cont.….

Complications
• Implant malposition
• Hemorrhage
• Infection
• Late corneal decompensation
• Complications that follow trabeculectomy may occur
• Late failure of MIGS increases the risk of bleb fibrosis
• Trabeculectomy be subsequently required to control the IOP

Combined Cataract & Filtering Surgery
There are three basic surgical approaches
• Cataract extraction alone, which may need to be followed by a trabeculectomy later
• Glaucoma filtering surgery alone, followed by cataract removal later (two-stage
Approach)
• Combined cataract and glaucoma surgery
Indications
• Cataract requiring extraction in a glaucoma pt who has advanced cupping & VF loss
• Cataract requiring extraction in glaucoma pt with poor compliance
• Cataract requiring extraction in glaucoma pt requiring multiple medications to
control lOP

Disadvantages of combined surgery versus cataract surgery alone
• Longer operating room time for procedure
• More complex postoperative care
• Slower visual recovery
• Possibly less IOP control versus trabeculectomy alone
• Possibly more astigmatism or myopic shift
• Long-term bleb problems

References
• American Academy of Ophthalmologists (2020-2021), Glaucoma. BCSC.
• J.J. Kanski. Clinical Ophthalmology, A systematic Approach, 9th ed.
• Shields Text book of Glaucoma 5th and 6th edition.
• AAO website
• https://www.slideshare.net/namratagupta96780/trabeculectomy-trabeculotomy-
goniotomy-and-their-complications

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