Conventional Filtering Procedures Flashcards - Medicine Terms

Chosing a mode of tx for an individual pt depends on what 3 things

• Stage of Glaucoma

• Level of IOP at diagnosis

• Life expectancy of the pt

List the 4 roles of Optometrists in glaucoma surgery

• familiarity of glaucoma surgeries performed today

• identifying appropriate surgical candidates

• making referrals to surgeons

• co-management of post-surgical pts

Surgery is aimed to either increase aqueous outflow or decrease aqueous production, which one is most commonly used

increase aqueous outflow

List the 3 major classes of surgical procedures

• conventional filtering procedures

• minimally invasive glaucoma surgeries (MIGS)

• ciliodestructive procedures

Choosing most appropriate class of surgery is dependent on what

the pt stage of glaucoma

Which of the 3 major classes of surgical procedures is typically favoured and why

MIGS

because minimally invasive means less complications

Which of the 3 major classes of surgical procedures is the gold standard for glaucoma

conventional filtering procedures

List the 2 examples of Conventional Filtering Procedures

• Trabeculectomy

• Tube-shunt implantation

Conventional Filtering Procedures are best used in glaucoma pt at what stage of their disease process

moderate to advanced stage

Describe the ideal Conventional Filtering Procedures candidate

pt with:

- moderate to advanced stage glaucoma

- showing signs of progression

- still has central vision

- cannot be adequately controlled using medications or laser therapy alone

Describe the ideal MIGS candidate

pt with:

- early stage glaucoma

- glaucoma already being well controlled with 1 or 2 meds

- already undergoing elective cataract surgery

Describe the ideal Ciliodestructive Procedure candidate

pt with:

- end-stage glaucoma

- central vision already lost

A pt with advance glaucoma (is/is not) a good Conventional Filtering Procedure candidate if their central vision is no longer intact, give 2 reasons why

is not

2 reasons why:

- there will be post-op inflammation and IOP spikes which could destroy the small amount of central vision this pt does have

- the goal of glaucoma management is to maintain functional vision... if the central vision is gone there is no point in performing the surgery because the benefit now no longer outweighs the risk

What is the general mechanism of MIGS

overcoming the trabecular meshwork's resistance to aqueous outflow and restoring flow through Schlemm's canal

Which class of procedure is particularly useful in complex glaucoma's, give 2 examples

ciliodestructive

- NVG

- uveitic

(these do not always response well to medical or conventional surgical approaches)

What is the goal of Ciliodestructive Procedures if the central vision is already gone

lower IOP to save the globe from needing to be enucleated

Define "Ab externo"

cutting from outside of the eye, inward

Define "Ab interno"

create channel from inside of the eye (anterior chamber) into to the TM

(still have to cut into the eye to get to the anterior chamber obviously)

Define a "penetrating surgery"

intra-operative entry into the anterior chamber

Define a "non-penetrating surgery"

no entry into the anterior chamber

Ab interno is an example of a (penetrating/non-penetrating) surgery

penetrative

MIGs is an example of a (penetrating/non-penetrating) surgery

penetrating

Ab externo is an example of a (penetrating/non-penetrating) surgery

non-penetrating

Aqueous shunt is an example of a (penetrating/non-penetrating) surgery

non-penetrating

Laser iridotomy is used for (open/closed) angle glaucoma

closed

Surgical iridectomy is used for (open/closed) angle glaucoma

closed

Laser iridoplasty is used for (open/closed) angle glaucoma

closed

Goniosynechiolysis is used for (open/closed) angle glaucoma

clased

Filtering surgery is used for (open/closed) angle glaucoma

both!

Alternative Incisional Surgery is used for (open/closed) angle glaucoma

open

Laser trabeculoplasty is used for (open/closed) angle glaucoma

open

Table of the classifications of surgical procedures on slide 8th

if youre interested

Trabeculectomy is an example of a (penetrating/non-prenetrating) (anterior/posterior) filtering technique

penetrating posterior

Deep Sclerectomy is an example of a (penetrating/non-prenetrating) (anterior/posterior) filtering technique

non-penetrating anterior

Canaloplasty is an example of a (penetrating/non-prenetrating) (anterior/posterior) filtering technique

non-penetrating anterior

Describe how a Trabeculectomy is done

an opening is created into the anterior chamber from underneath a partial thickness scleral flap to allow for aqueous flow out of the anterior chamber

aqueous flows into the subconjunctival space, usually leading to an elevation of the conjunctiva, referred to as a filtering bleb

aqueous then exits the bleb through a variety of ways

image slide 13

List the 4 different ways aqueous exits the bleb formed in a Trabeculectomy

• filtration through the conjunctiva into the tear film

• absorption by vascular or perivascular conjunctival tissue

• flow through lymphatic vessels near the margins of the surgical area

• drainage through aqueous veins

Trabeculectomy is a procedure best for pt with (early/moderate/advanced) glaucoma damage

advanced

If referring a pt for a Trabeculectomy, you must first ensure which ocular structure is in pristine condition

conjunctiva

(T/F) Trabeculectomy should not performed on a pt who has a hx of past ocular surgeries

TRUE

ocular surgery would mean some kind of insult to the conj in the past

What is the benefit of forming a flap with a Trabeculectomy rather than a direct entry hole

slows the flow of the aqueous

if it was a direct hole the aqueous would just shoot straight out & you would risk hypotony

List 6 indications for Trabeculectomy

• Intolerable eye pain due to uncontrolled IOP

(Traumatic hyphema, emergency case)

• Progressive optic nerve damage due to uncontrolled IOP

• Visual Field loss due to uncontrolled IOP

• Uncontrolled IOP that is anticipated to worsen the ON, VF or visual function

• Intolerance to glaucoma medications

• Noncompliance to glaucoma medications

List 7 contraindications for Trabeculectomy

• cases that are likely to respond well to less invasive treatments (eg,medications, laser iridotomy)

• Eyes with previous failed trabeculectomy

• Eyes with severely scarred conjunctiva (e.g. chemical burns, Stevens-Johnsonsyndrome)

• Neovascular glaucoma with active neovascularization

• Uveitic glaucoma

(surgery would exacerbate this issue)

• Blind eyes

(benefit does not out weigh risk)

• Unstable systemic medical condition

(must be able to undergo sedation)

(T/F) Pt taking anticoagulants are contraindicated for trabeculectomy

FALSE

caution should be taken with them because bleeding complications are increased - but it is not contraindicated

List the 2 ways that antimetabolites are administered during a Trabeculectomy

- surgical sponge

- injection in subconjunctival space

List tehe 2 most commonly used antimetabolites in Trabeculectomy

• 5-fluorouracil (5-FU)

• Mitomycin C (MMC)

(5-FU/MMC) is more popular in the US, but less popular worldwide

MMC

What is the mechanism and purpose of antimetabolites in a Trabeculectomy

they interfere with DNA synthesis... this diminishes and prevents cell replication to prevent scarring

(5-FU/MMC) is more expensive

MMC

(5-FU/MMC) is more effective

MMC

(5-FU/MMC) is stable at room temperature

5-FU

List the 4 advantages of 5-FU antimetabolites

- cheap

- no dilution or dosage calculation

- stable at room temperature

- better safety margin

List 3 disadvantages of 5-FU antimetabolites

- less effectiv

- multiple injections

- high corneal toxicity

List 2 advantages of MMC antimetabolites

- more potent

- lower IOP

list 3 disadvantages of MMC antimetabolites

- expensive

- complicate storage (not stable at room temp)

- possibly more complications

(T/F) Mini bubbles on the top of a bleb are a bad sign

FALSE

seeing these mini bubbles is how you know the bleb is functioning (thats the AH leaving)

if there are no bubbles that doesnt necessarily mean its not working

check IOP to ensure if its working or not

List the 7 serious postoperative complications that may arise due to the penetrating nature of Trabeculectomy

• Hypotony

• Hyphema

• Flat anterior chamber

• Choroidal detachment

• Choroidal effusion

• Endophthalmitis

• Surgery induced cataract

The IOP drop after a Trabeculectomy surgery is not predictable and highly dependent on:

scarring/healing

List 2 types of non-prenetrating filtering surferies

- deep sclerectomy

- aqueous shunts

Deep sclerotomy is a (penetrating/non-penetrating) filtering surgery

non-penetrating

Which procedure involves exposure of schlemm's canal without fully penetrating the eye leading to creation of an intrascleral bleb

deep sclerectomy

Which procedure involves placing a flexible plastic tube with an attached silicone drainage pouch inthe eye to help drain aqueous

aqueous shunts

Aqueous shunt surgeries are usually done after _______________

a trabeculectomy that failed

During a Deep Sclerectomy, there is careful removal of the _______________ and the ___________________... the ______________ and the _______________ remain in place

removal:

- inner wall of schlemm's canal

- juxtacanalicular meshwork

remain:

- uveoscleral meshwork

- corneoscleral meshworks

What is the purpose of the spacer inserted during a Deep Sclerectomy

maintains intrascleral blebpatency and prevents collapse ofthe bleb

Space maintainer inserted during a Deep Sclerectomy dissolves over about __________

9 months

List the 2 different types of space maintainers used in Deep Sclerectomy procedures

• AquaFlow

• Collagen implant

What would warrant performing an Aqueous Shunt Surgery as a early tx option for a pt

if pt already has or is likely to form scar tissue in the eye

List the 3 different options for a choice of Aqueous Shunt implant

• Ahmed

• Baerveldt

• Molteno

An Ahmed shunt implant (does/does not) have a valve

does

image slide 30

A Baerveldt shunt implant (does/does not) have a valve

does not

image slide 31

A Molteno shunt implant (does/does not) have a valve

does not

image slide 32

Valved shunt implants have (lower/higher) risk for hypotony

lower

Non-valved shunt implants have (lower/higher) risk for hypotony

higher

Valved shunt implants have (lower/higher) risk for complications

lower

Non-valved shunt implants have (lower/higher) risk for complications

higher

Valved shunt implants leave (lower/higher) IOP

higher

Non-valved shunt implants leave (lower/higher) IOP

lower

Explain the mechanism of how aqueous shunts work

a tube traveling from the anterior chamber to a predetermined bleb area (plate) allows for the diversion of AH to the equatorial region and away from the limbal subconjunctival space

What are the two most common glaucoma surgeries worldwide

• Trabeculectomy

• Tube shunt surgery

The TVT study was introduced to observe whether tube-shunt devicesoffered advantages over trabeculectomy in patients who:

hadundergone previous glaucoma surgery

What was the conclusion made from the TVT study

both procedures:

- significant and sustained reduction in IOP

• reduced dependence on glaucoma meds following surgery

However...the trab group had significant higher failure rate after five year follow up

The TVT study found that the (tube/trab) group had a high rate of inadequate IOP reduction after 5yrs

trab

If a tube-shunt procedure fails, the pt surgical options are limited to what 2 things

• Place a second shunt inferiorly in the eye

• Cyclodestruction

What is the main take-home message from the VTV study

It is more efficacious to implant a glaucoma drainage device to control IOP than to perform a repeat trabeculectomy on patients who have previously had intraocular surgery, especially those who underwent trabeculectomy

A new TVT study has shown that :

Trabeculectomy with MMC had a (lower/higher) surgical success rate than tube shunt implantation after 3 years in the PTVT Study

higher

A new TVT study has shown that :

Trabeculectomy with MMC produced (lower/higher) IOP with use of (fewer/more) glaucoma medications compared with tube shunt surgery

lower

fewer

A new TVT study has shown that :

Tub shunt surgery resulted in (lower/higher) incidence of serious complications producing vision loss or requiring reoperation compared to trabeculectomy with MMC

lower