Glaucoma laser Flashcards by Catherine Simard

Définition de l’abréviation LASER

Light Amplification by Stimulated Emission of Radiation

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Propriétés d’un laser (x5)

Monochromatic
Coherence
Directionality
Polarization
Intensity

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Interactions Laser-Tissue (x3)

PHOTOCOAGULATION : selective absorption of light energy and conversion of that energy to heat, with subsequent thermally included structural change in the target. Ex. ARGON

PHOTODISRUPTION : High-peak-power pulsed laser to ionize the target and rupture the surrounding tissue. Explosive disruption of tissue to create an excision. Ex. YAG

PHOTOABLATION : Break the chemical bonds that hold tissue together - vaporizing the tissue. Ex. EXCIMER LASER

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Indications d’un iridotomie au laser (x3)

Pupil block angle closure
Narrow/occluable angles
Pigment dispersion syndrome/glaucoma

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Contre-indications relatives de l’irodotomie au laser (x5)

Flat anterior chamber
Completely sealed angle
Angle-closure due to primary SYNECHIAL closure
Uncooperative patient
No view (corneal edema, corneal opacification)

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Gouttes à administrer pré-iridotomie au laser

Pilocarpine 2% (4% si iris foncé)
Alphagan/Apraclonidine
Topical anesthetic

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Site(s) de l’iridotomie au laser

Iris crypt
Area of thinning (choisir l’endroit le plus mince possible)
Temporal > Nasal (En supérieur : Dysphotopsie)
Éviter 3h et 9h : entrée des nerfs ciliaires

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Laser(s) utilisés pour iridotomie

YAG laser : le PLUS commun
- Lower closure rate compared to Argon
- Less energy compared to Argon

Argon : can be used to PRE-treat thick iris prior to YAG

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Post-operative care d’un glaucoma laser

IOP check 1-3 hours post-laser
Stéroïdes topiques : q2h x 2 jours, QID x 5 jours puis plus longtemps prn si persistance inflammation
Check IOP, AC reaction, patency 1-4 weeks after laser

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Complications de l’iridotomie au laser

IOP spike (le plus fréquent)
- 30-40% > 10 mmHg within 1-3 hours post LPI
- Uncommon with alpha-2 agonist prophylaxis
- Risk : increased baseline IOP, PAS > 180°
Anterior uveitis
Diplopia and glare
Hemorrhage
- 50% avec YAG, rare avec Argon
- FdR : rubeosis, anticoagulants, uveitis
Corneal damage
Pupillary abnormalities
Posterior synechia
Lens opacities (progression of cataract)
Closure of iridotomy
Retinal damage

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Types de Laser Trabeculopasty

Argon Laser Trabeculoplasty (AL)
Selective Laser Trabeculoplasty (SLT)
Micropulse Diode Laser Trabeculoplasty
Titanium Sapphire Laser Trabeculoplasty
Pattern Scan Laser (PASCAL) Trabeculoplasty

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Indications de la trabeculoplasty

Open angles
Adjunctive or 1st line treatment
OHTN (ocular hypertension)
POAG (primary open angle glaucoma)
PXG/PXF (Pseudoexfoliative glaucoma)
PDG/PDS (Pigmentary Glaucoma/Pigment Dispersion Syndrome)
NTG
Steroid induced

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Mécanisme d’action du ALT

Increased phagocytotic activity
Decreased resistance to outflow (increased DNA replication of cells + increased metallo-poteinase levels whitin trabecular meshwork)

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Evidence of ALT

20-30% IOP reduction in 75-85%
Efficacy decreases by 50% over 5 years, and 32% over 10 years
Repeat ALT success rates : 21-70% with additional decreased success over time (DONC pas vrmt répétable)
Largest IOP reductions and earlier failures noted in PXG

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Complications laser trabeculoplasty

IOP spike 30-50% (higher avec ALT, PDS/PDG)
Uveitis
Peripheral anterior synechia (PAS) formation (more common with ALT)
CME (rare)
Subretinal fluid (rare)
Choroidal effusion (rare)

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Mécanisme d’action du SLT

Selective photothermolysis with marked absorption by melanin pigment granules : avoid thermal damage to surrounding non-pigmented cells

Lower energy than ALT

(En pratique, on utilise plus SLT que ALT)

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Evidence of SLT

Succès rate over 70% achieved up to 30 months after treatment
Effective as using prostaglandins in first time treatment
REPEATABLE after prior SLT, even if initial response was limited
Pre-treatment with PGAs associated with decreased IOP-lowering response
Anti-inflammatory drops after SLT do not cause a significant reduction in inflammation or altered IOP lower efficacy

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Contre-indications de la laser trabeculoplasty

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Uncooperative patient
Inadequate visualization
Complete angle closure

Mécanismes d’action ALT versus SLT

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ALT :
- Augmente phagocytose
- Decreased resistance outflow

SLT :
- Selective targeting of pigmented TM
- Moins d’É que ALT

Evolution ALT versus SLT

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ALT :
- Diminution 20-30% IOP in 75-85%
- Efficacy 50% over 5 years
- PXG largest IOP reduction and earlier failure

SLT :
- Diminution 25-30% in 70% up to 30 months
- Effective as PGAs in first line Tx
- Repeatable after prior SLT even if initial response limited

Indications Laser Peripheral Iridoplasty

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Medically unbreakable attack of ACG
Plateau iris syndrome
Nanophtalmos
Preparation for laser trabeculoplaty when iriocorneal angle is narrow
Phacomorphic angle closure

Contre-indications Laser Peripheral Iridoplasty

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Flat anterior chamber
Advanced corneal edema or opacification

Gouttes pré-Tx Laser Peripheral Iridoplasty

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Pilocarpine 2% (4% si iris foncé)
Alphagan/Apraclonidine
Topical anesthetic

Site Selection of Laser Peripheral Iridoplasty

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Peripheral location

Laser utilisé pour Laser Peripheral Iridoplasty

Argon 85-90% angles remained open for up to 10 years in plateau iris after 1 session

Post-operative management of Laser Peripheral Iridoplasty

IOP check 1-3 hours after Topical steroids (q2h x 2 jours, QID x 5 jours et plus longtemps prn)

Complications of Laser Peripheral Iridoplasty

IOP spike Anterior uveitis Iridolenticular or angles synchiaes Iris atrophy Atonic pupil Corneal endothelial burns Urrets-Zavalia syndrome - prolonged mydriasis unresponsive to pilocarpine (usually resolves spontaneously within 1 year)

Indication d'une cyclophotocoagulation transsclérale

High risk of failure with filtering surgery or GDD - Failed filtering surgery/GDD - NVG (glaucome néovx) - Post traumatic glaucoma - Post PKP - Post chemical/thermal burn - Silicone oil - Aphakic glaucoma - Uveitic glaucoma Poor VA potential No visual potential Refusing surgery

Operative considerations with cyclophotocoagulation transsclérale

Retro/peribulbar block (car très douloureux) Retro-luminate globe to determine position of ciliary body Setting : SPARE 3 & 9 o'oclock

Post-operative management of cyclophotocoagulation transsclérale

Stéroïdes ++ : Pred q2h x 1-2 weeks with taper (slow taper sur des mois) Atropine 1% BID Continue all glaucoma medications, except miotics Can retreat at 1 month

Complications du cyclophotocoagulation transsclérale

Higher energy = increased risk of complications Mild : - Iritis - Conjunctival edema - Transient pain Severe: - Phthisis bulbi - Permanent hypotony - Anterior segment hemorrhages - Decreased vision - Sympathetic ophtalmia --> 007%

Différence entre la cyclophotocoagulation transsclérale MICROPULSE versus transsclérale?

MICROPULSE : Similar effectiveness as cyclophotocoagulation transsclérale with LESS side effects No hypotony or visual loss reported

Types de cyclophotocoagulation

Transsscleral cyclophotocoagulation Micropulse Cyclocryotherapy Endoscopic cyclophotocoagulation

Quel cyclophotocoagulation affects nerves of cornea? Quel est l'avantage?

Cyclocryotherapy : affects sensory nerves of cornea benefit in painful eye

Quel est l'avantage de la cyclophotocoagulation endoscopique?

Decreases risk of overtreatment and phthisis bulbi compared to trans-scleral technique Applied diode laser energy directly to the ciliary processes via fibre optic endoscope Can be combined with CEIOL (cataract extraction & IOL) : showed decrease in IOP at all time points after 35 months Can be used to mechanically rotate ciliary processes to open angle further in plateau iris

Complications de la cyclophotocoagulation endoscopique?

IOP spike Inflammation CME Hypotony Phthisis Choroidal hemorrhage Retinal detachment Fibrin deposition in AC

Quel laser utilise-t-on pour une lyse des sutures de nylon?

Argon : lysis of nylon sutures in trabeculectomy to titrate filtration

Complications de la lyse de sutures au laser dans un contexte de trabeculectomy?

Over-filtration with flat AC Conjunctival perforation

Indication de l'anterior hyaloid disruption?

Treatment of malignant glaucoma Phakic eyes : Argon Pseudophakic/Aphakic : YAG

Indication et fonctionnement du Laser Goniopuncture

Adjunctive procedure for non-filtering glaucoma surgery : deep sclerectomy, viscocanalostomy, canaloplasty Creates holes in the trabeculo-desmet window to allow for greater IOP lowering Achieve 20% IOP reduction and stable for a least 2 year in about 50% of cases

Complications du Laser Goniopuncture

Complications (low) : Hyphema Iritis Peripheral synechiae Iris incarceration Hypotony Late bleb leak

Objectif du Laser Assisted Deep Sclerectomy

Aim to simplify the manual deep sclerectomy procedure Technique : Manual creation of superficial flap Repeated laser applications to cause progressive ablation of the thin layers of deep scleral tissue until aqueous percolation is achieved

Autres types d'utilisation de laser

Pupilloplasty Photomydriasis Sphincterotomy Goniophotocoagulation Cyclodialysis cleft Epithelial down growth Shrinkage of conjunctival blebs

Glaucoma laser Flashcards

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