Glaucoma laser Flashcards
Définition de l’abréviation LASER
Light Amplification by Stimulated Emission of Radiation
Propriétés d’un laser (x5)
Monochromatic
Coherence
Directionality
Polarization
Intensity
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
Indications d’un iridotomie au laser (x3)
Pupil block angle closure
Narrow/occluable angles
Pigment dispersion syndrome/glaucoma
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)
Gouttes à administrer pré-iridotomie au laser
Pilocarpine 2% (4% si iris foncé)
Alphagan/Apraclonidine
Topical anesthetic
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
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
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
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
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
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
Mécanisme d’action du ALT
Increased phagocytotic activity
Decreased resistance to outflow (increased DNA replication of cells + increased metallo-poteinase levels whitin trabecular meshwork)
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
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)
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)
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
Contre-indications de la laser trabeculoplasty
Uncooperative patient
Inadequate visualization
Complete angle closure
Mécanismes d’action ALT versus SLT
ALT :
- Augmente phagocytose
- Decreased resistance outflow
SLT :
- Selective targeting of pigmented TM
- Moins d’É que ALT
Evolution ALT versus SLT
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
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
Flat anterior chamber
Advanced corneal edema or opacification
Gouttes pré-Tx Laser Peripheral Iridoplasty
Pilocarpine 2% (4% si iris foncé)
Alphagan/Apraclonidine
Topical anesthetic
Site Selection of Laser Peripheral Iridoplasty
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
