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Lasers in Glaucoma 
Presenter:Dr.Parth Satani 
Moderator:Dr.Rita Dhamankar
Introduction 
 A laser is a device that emits light through a process of optical 
amplification based on the stimulated 
...
Lasers used in glaucoma 
 488 - 514 nm - Argon blue-green & green 
 810 nm Diode 
 1064 nm - Nd:YAG 
 10,600 nm - Carb...
Different types of laser 
Gas 
Argon 
Krypton 
Helium 
Neon 
Carbon Dioxide 
Solid State 
Ruby 
Nd Yag 
LASERS 
Metal 
Vap...
Three basic light-tissue 
interactions 
 Photocoagulation 
 Laser light is absorbed by the target tissue or by neighbori...
 Photoablation: 
 breaks the chemical bonds that hold tissue together, 
essentially vaporizing the tissue
Modes of operation 
 Continuous Wave (CW) Laser: It delivers the energy in a continuous 
stream of photons. 
 Pulsed Las...
Lasers in Open angle glaucoma 
 Outflow enhancement 
 Laser trabeculoplasty 
 Inflow reduction 
 Cyclophotocoagulation...
Lasers in Angle closure glaucoma 
 Relief of pupillary block 
 Laser iridotomy 
 Modification of iris contour 
 Laser ...
Lasers in Post-operative treatment 
 Laser suture lysis 
 Adjacent to trabeculectomy 
 Laser sclerostomy 
 Laser gonio...
Nd:YAG laser 
 Beckman and Sugar in 1973 were first to use Nd:YAG laser 
 Neodymium crystal is embedded in yttrium-alumi...
 Q-switched and mode locked regime 
 truly pulsed lasers with emissions of high power density in very 
short duration. 
...
Q-switched Mode lock 
Duration 10-20ns 30-70ns 
Irradiance 106 109 
Optical switching Pockel cell/dye Dye 
Efficiency Bett...
Laser iridotomy 
 Laser treatment to connect anterior and posterior 
chamber to relieve pupillary block. 
 Effective for...
indication 
 Definitive indications 
 Acute angle closure. 
 Chronic (creeping) angle closure 
 Mixed mechanism glauco...
 Relative indications 
 Critically narrow angles in asymptomatic patients 
 Younger patients, especially those who live...
Types of laser 
 Photodisruptive Nd:YAG laser,(Q-switched and mode-lock) 
 The photothermal argon lasers
Patient preparation 
 Pilocarpine 1% is instilled twice, 5 minutes apart; miosis helps to 
stretch and thin the iris. 
 ...
Lens choice 
 Abraham lens- 66D planoconvex button. 
 The Wise lens -103D planoconvex button, 
 concentrates the laser ...
Specific techniques 
 Place- peripheral iris under the upper eyelid to avoid ghost 
images that may arise through the iri...
Laser Iridotomy - position
Nd-YAG laser 
 The energy- 3–8 mJ, 
 Pulses- there are 1–3 per shot, and one or more shots are used 
for penetration 
 ...
Argon laser 
 Long pulses (0.2 seconds) for light-colored irides (blue, hazel, 
light brown), 
 short pulses (0.02–0.05 ...
Post laser management 
 Steroids are given 4 times a day for 7 days to reduce post 
laser inflammation . 
 Anti-glaucoma...
Argon versus Nd:YAG Laser 
 . 
Argon laser Nd:YAG laser 
Uptake of energy Require pigmented 
cells 
Doesn’t require 
Iris...
Combined Argon Nd:YAG 
technique 
 Used in sequential combination for dark brown irides or for 
patients who are on chron...
Complications 
 Intraocular Pressure Spikes 
 Laser-Induced Inflammation 
 Iridectomy Failure 
 Diplopia 
 Bleeding 
...
Laser peripheral iridoplasty 
 It is an effective means of opening an 
appositionally closed angle. 
 Procedure consists...
Laser Iridoplasty 
Note the almost 
Ring like burns for laser 
iridoplasty
 Spot size : 100–200- μm 
 Power: 100–30o mW 
 Duration : 0.1 second. 
 Lighter irides will require slightly higher en...
Indication 
 Attack of angle closure glaucoma 
 Plateau iris syndrome commonest indication 
 Angle closure related to s...
Contraindications 
 Contraindication 
 Advanced corneal edema or opacification 
 Flat anterior chamber 
 Synechial ang...
Laser trabeculoplasty 
 Relatively effective,non-invasive. 
 Laser treatment to trabecular meshwork increase to 
increas...
Mechanism of action 
 Wise and Witter proposed that thermal energy produced by 
absorption of laser by pigmented trabecul...
Laser trabeculoplasty 
 Method 
 Argon laser trabeculoplasty 
 Selective laser trabeculoplasty 
 Lens 
 Goldmann 3 mi...
Argon laser trabeculoplasty 
 Laser parameter 
 Power -300-1200mW 
 Spot size—50μm 
 Duration -0.1 sec 
 Number of bu...
Argon laser trabeculoplasty 
 Ideally,spot should be applied 
Over schlemm’s canal avoding 
The iris root at the junction...
Selective laser trabeculoplasty 
 SLT target pigmented trabecular meshwork cells without 
causing thermal damage to non-p...
Selective laser trabeculoplasty (arrow) versus argon laser trabeculoplasty 
treatment (arrowhead). (Courtesy of M. Berlin,...
Comparison 
ALT SLT 
TYPE OF LASER Argon blue green 
488/514nm 
Double frequency 
Nd:YAG 532nm 
Spot size(μm) 50 400 
Dura...
Indications 
 Chronic open angle glaucoma 
 Exfoliation syndrome 
 Pigmentary glaucoma 
 Glaucoma in aphakia or pseudo...
Contraindications 
 Closed or extremely narrow angles 
 Corneal edema 
 Aphakia with vitreous in ant.chamber 
 Vascula...
Complications 
 Most common risk is IOP spikes in about 3–5% of patients 
 Iritis 
 Peripheral ant.synechiae 
 Hemorrh...
Comparison 
 ALT maintained IOP control in 67–80% of eyes for 1 year, in 35– 
50% for 5 years, and in 5–30% for 10 years ...
Lasers in malignant glaucoma 
 Argon laser 
 Power :200–800 mW 
 Duration :0.1 second 
 spot size :100–200- μm. 
 Thi...
 In aphakic ciliary block glaucoma the Nd:YAG laser can rupture 
the vitreous face and break the block. 
 Pseudophakic c...
Cyclophotocoagulation 
 Reduce aqueous production by destruction of ciliary 
epithelium 
 Techniques 
 Transscleral 
 ...
Cyclophotocoagulation 
 Trans-scleral cyclophotocoagulation 
 destroys ciliary epithelium and associated vasculature 
 ...
Cyclophotocoagulation 
 Trans-scleral Cyclophotocoagulation 
 Noncontact Nd:YAG laser cyclophotocoagulation 
 Contact N...
Cyclophotocoagulation 
 Noncontact Nd:YAG laser cyclophotocoagulation 
 Nd:YAG laser is mounted on slit-lamp 
 4–8 J/pu...
Cyclophotocoagulation 
 Contact Nd:YAG laser cyclophotocoagulation 
 Nd:YAG laser in the continuous mode via a fiber opt...
Cyclophotocoagulation 
 Semiconductor diode laser trans-scleral 
cyclophotocoagulation 
 most widely used method of cili...
ENDOSCOPIC LASER 
CYCLOPHOTOCOAGULATION
ENDOSCOPIC LASER 
CYCLOPHOTOCOAGULATION 
 Performed with an 810 nm diode laser 
 Xenon light source that provides illumi...
Comparison
Complications 
 Conjunctival burn 
 Hyphema 
 Inflammation 
 Pain 
 IOP spike 
 Cataract 
 Pupil abnormality 
 Hyp...
CO2 Laser Assisted Sclerectomy 
Surgery 
 Similar to trabeculectomy 
 Major difference being that after the scleral flap...
CO2 Laser Assisted Sclerectomy 
Surgery
Drawbacks 
 Demands careful and delicate surgery 
 Relatively long learning curve 
 Can be performed only by highly ski...
Laser suture lysis 
 Subconjunctival trabeculectomy flap sutures can be lysed with 
the laser postoperatively if there is...
Method 
Laser suture lens. The device has a small convex lens that compresses the edematous 
conjunctiva permitting a clea...
 Dense hemorrhage in the tissues overlying the suture will 
absorb the energy, prevent treatment, and possibly cause 
con...
Reopening of failed filtration 
site  Filtering sites can close because of fibrosis on the external side 
 Membrane form...
Femto laser in the offing 
 Applications for the femto laser ab externo include 
 Creating trabeculectomy flaps, 
 Non-...
Excimer Laser 
 ab interno procedures include 
 ELT (excimer laser trabeculostomy) equivalent using 
docked gonio lens d...
Cyclodialysis and laser 
 Cyclodialysis clefts have been both opened and closed with laser 
 Argon laser photocoagulatio...
Laser synechiolysis 
 The argon laser can be used to pull early or lightly adherent 
peripheral anterior synechiae away f...
 The Nd:YAG laser can lyse iris adhesion. 
 Use- early irido–corneal–endothelial (ICE) syndrome to disrupt 
synechiae, 
...
Goniophotocoagulation 
 Use - anterior segment neovascularization 
 Goniophotocoagulation is useful to obliterate fragil...
Other uses of lasers 
 Goniopunctures in NPGS is mandatory, after a while, 
as during the surgical procedure itself, the ...
Goniopuncture 
Lasering the bleb
Lasers in Glaucoma - 
Summarizing 
 Lasers in glaucoma are an important part of the 
armamentarium in the management. 
 ...
Lasers in Glaucoma
Lasers in Glaucoma
Lasers in Glaucoma
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Lasers in Glaucoma

Lasers in Glaucoma, Dr.Parth Satani, Dr.Rita Dhamankar, Laxmi Eye Institute

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Lasers in Glaucoma

  1. 1. Lasers in Glaucoma Presenter:Dr.Parth Satani Moderator:Dr.Rita Dhamankar
  2. 2. Introduction  A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.  Properties of laser  Monochromatic  Coherent  Parallelism  Brightness
  3. 3. Lasers used in glaucoma  488 - 514 nm - Argon blue-green & green  810 nm Diode  1064 nm - Nd:YAG  10,600 nm - Carbon dioxide
  4. 4. Different types of laser Gas Argon Krypton Helium Neon Carbon Dioxide Solid State Ruby Nd Yag LASERS Metal Vapour Copper Gold EXCIMER Dye Diode Argon Fluoride
  5. 5. Three basic light-tissue interactions  Photocoagulation  Laser light is absorbed by the target tissue or by neighboring tissue, generating heat that denatures proteins (i.e., coagulation)  Photodisruption  Power density is so great that molecules are broken apart into their component ions, creating a rapidly expanding ion ‘plasma.’ This ionization and expanding plasma create subsequent shock-wave effects which cause an explosive disruption of tissue to create an excision
  6. 6.  Photoablation:  breaks the chemical bonds that hold tissue together, essentially vaporizing the tissue
  7. 7. Modes of operation  Continuous Wave (CW) Laser: It delivers the energy in a continuous stream of photons.  Pulsed Lasers: Produce energy pulses of a few micro to milliseconds.  Q Switched Lasers: Deliver energy pulses of extremely short duration (nanosecond).  Mode-locked Lasers: Emits a train of short duration pulses (picoseconds to femtoseconds)
  8. 8. Lasers in Open angle glaucoma  Outflow enhancement  Laser trabeculoplasty  Inflow reduction  Cyclophotocoagulation(for end stage disease)
  9. 9. Lasers in Angle closure glaucoma  Relief of pupillary block  Laser iridotomy  Modification of iris contour  Laser iridoplasty  Inflow reduction  Cyclophotocoagulation(end stage disease)
  10. 10. Lasers in Post-operative treatment  Laser suture lysis  Adjacent to trabeculectomy  Laser sclerostomy  Laser gonio-puncture  Adjacent to non-penetrating surgery
  11. 11. Nd:YAG laser  Beckman and Sugar in 1973 were first to use Nd:YAG laser  Neodymium crystal is embedded in yttrium-aluminium garnet  It can be operated in  Free mode  Q-switched  Mode locked regime  Free mode has thermal effect on tissue  While Q-switched and mode locked have photo disruptive effect.
  12. 12.  Q-switched and mode locked regime  truly pulsed lasers with emissions of high power density in very short duration.  Q-switched system  energy within the laser cavity is raised several times by making the usually partially reflective mirror totally opaque.  Then suddenly making it transparent again by using polaroid filters  So there is rapid depletion of energy confined within laser cavity.
  13. 13. Q-switched Mode lock Duration 10-20ns 30-70ns Irradiance 106 109 Optical switching Pockel cell/dye Dye Efficiency Better Poor •In pockel cell - optical switching occurred by electrical modulation •While in dye - optical switching occurs when the energy buildup becomes very high •So dye driven switches are inefficient and prone to malfunctioning.
  14. 14. Laser iridotomy  Laser treatment to connect anterior and posterior chamber to relieve pupillary block.  Effective for pupillary block  Relatively non invasive  Preferable to surgical iridotomy
  15. 15. indication  Definitive indications  Acute angle closure.  Chronic (creeping) angle closure  Mixed mechanism glaucoma  Phacomorphic with an element of pupillary block  Iris bombé
  16. 16.  Relative indications  Critically narrow angles in asymptomatic patients  Younger patients, especially those who live some distance from medical care or who travel frequently  Narrow angles with positive provocative test  Iris–trabecular contact demonstrated by compression gonioscopy
  17. 17. Types of laser  Photodisruptive Nd:YAG laser,(Q-switched and mode-lock)  The photothermal argon lasers
  18. 18. Patient preparation  Pilocarpine 1% is instilled twice, 5 minutes apart; miosis helps to stretch and thin the iris.  Proparacaine 0.5% drops are instilled immediately before the procedure
  19. 19. Lens choice  Abraham lens- 66D planoconvex button.  The Wise lens -103D planoconvex button,  concentrates the laser energy more  it minimizes the spot and magnifies the target even more  difficult to focus.  Advantage of the Abraham lens -energy delivered to both cornea and retina is four times less than that with Wise lens.
  20. 20. Specific techniques  Place- peripheral iris under the upper eyelid to avoid ghost images that may arise through the iris hole.  Iris crypts represent thinner iris segments and, as such, are penetrated more easily.  The superonasal position (at 11 and 1 o’clock) is the best position to use to prevent inadvertent irradiation of the fovea
  21. 21. Laser Iridotomy - position
  22. 22. Nd-YAG laser  The energy- 3–8 mJ,  Pulses- there are 1–3 per shot, and one or more shots are used for penetration  The Q-switched mode is used  Place-between the 11 and 1 o’clock positions,  Iris blood vessels are avoided
  23. 23. Argon laser  Long pulses (0.2 seconds) for light-colored irides (blue, hazel, light brown),  short pulses (0.02–0.05 seconds) for dark brown irides.  Power; 1000 mW  Spot size ; 50 μm  single area is treated with superimposed applications until perforation is obtained  pigment flume is found to move forward (“smoke sign” or “waterfall sign”) Del Priore L.V., Robin A.L., Pollack I.P.: Neodymium:YAG and argon laser iridectomy: long term follow-up in a prospective randomized clinical trial. Ophthalmology 1988; 95:1207-1211
  24. 24. Post laser management  Steroids are given 4 times a day for 7 days to reduce post laser inflammation .  Anti-glaucoma medication like B-blockers are given 2 times a day for 7 days to reduce chances of post laser IOP spike.  Patient is re-checked after 7 days for IOP and patency of iridotomy.
  25. 25. Argon versus Nd:YAG Laser  . Argon laser Nd:YAG laser Uptake of energy Require pigmented cells Doesn’t require Iris colour Dark brown Light and medium colour iris Late closure High chance Less chance
  26. 26. Combined Argon Nd:YAG technique  Used in sequential combination for dark brown irides or for patients who are on chronic anticoagulant therapy  First, the argon laser (short-pulse mode) is used to attenuate the iris to about one fourth the original thickness and to coagulate vessels in the area.  Then Nd:YAG laser is used, with the beam focused at the center of the crater; one or more bursts are used to complete the iridectomy.
  27. 27. Complications  Intraocular Pressure Spikes  Laser-Induced Inflammation  Iridectomy Failure  Diplopia  Bleeding  Lens Opacities  Corneal Injury
  28. 28. Laser peripheral iridoplasty  It is an effective means of opening an appositionally closed angle.  Procedure consists of placing contraction burns in the extreme periphery to contract the iris stroma between the site of burn and the angle so it physically opens an angle.  Argon laser are used with the lowest power setting that creates contraction of the iris
  29. 29. Laser Iridoplasty Note the almost Ring like burns for laser iridoplasty
  30. 30.  Spot size : 100–200- μm  Power: 100–30o mW  Duration : 0.1 second.  Lighter irides will require slightly higher energy levels than darker  Ten to twenty spots evenly distributed over 360º of the iris are usually sufficient
  31. 31. Indication  Attack of angle closure glaucoma  Plateau iris syndrome commonest indication  Angle closure related to size or position of lens  Nanophthalmos  Facilitate access to the trabecular meshwork for laser trabeculoplasty  Minimize the risk of endothelial damage during iridotomy
  32. 32. Contraindications  Contraindication  Advanced corneal edema or opacification  Flat anterior chamber  Synechial angle closure  Complication:  mild iritis  Corneal endothelial burn  Transient rise in IOP
  33. 33. Laser trabeculoplasty  Relatively effective,non-invasive.  Laser treatment to trabecular meshwork increase to increase outflow.
  34. 34. Mechanism of action  Wise and Witter proposed that thermal energy produced by absorption of laser by pigmented trabecular meshwork caused shrinkage of collagen of trabecular lamellae this opened up intertrabecular space in untreated region and expanded schlemm’s canal by pulling the meshwork centrally  Elimination of some trabecular cells posttrbeculoplasty.this stimulate remaining cells to produce different composition of extracellular matrix with lesser outflow obstructing properties.
  35. 35. Laser trabeculoplasty  Method  Argon laser trabeculoplasty  Selective laser trabeculoplasty  Lens  Goldmann 3 mirror lens  Latina trabeculoplasty lens:
  36. 36. Argon laser trabeculoplasty  Laser parameter  Power -300-1200mW  Spot size—50μm  Duration -0.1 sec  Number of burns-30-50 spots evenly placed over 180deg. remaining in subsequent visit.
  37. 37. Argon laser trabeculoplasty  Ideally,spot should be applied Over schlemm’s canal avoding The iris root at the junction of Anterior 1/3 to posterior 2/3 of Meshwork.  The energy level should be set To induce a reaction from a Slight transient blanching of The treated area to small Bubble formation
  38. 38. Selective laser trabeculoplasty  SLT target pigmented trabecular meshwork cells without causing thermal damage to non-pigmented cells or structure.  Laser :Frequency doubled Q switched ND:YAG laser  Pulse :3nsec.  Spot size 400 μm  Power :o.8 mJ power  No.of spots :apprx.50 spots are applied  End point :minimal bubble or no bubble
  39. 39. Selective laser trabeculoplasty (arrow) versus argon laser trabeculoplasty treatment (arrowhead). (Courtesy of M. Berlin, MD.)
  40. 40. Comparison ALT SLT TYPE OF LASER Argon blue green 488/514nm Double frequency Nd:YAG 532nm Spot size(μm) 50 400 Duration 0.1s 3ns Power 300–900 mW 0.6–1.2 mJ Degrees 180 180–360
  41. 41. Indications  Chronic open angle glaucoma  Exfoliation syndrome  Pigmentary glaucoma  Glaucoma in aphakia or pseudophakia
  42. 42. Contraindications  Closed or extremely narrow angles  Corneal edema  Aphakia with vitreous in ant.chamber  Vascular glaucoma  Acute uveitis  Primary congenital glaucoma  Angle recession glaucoma
  43. 43. Complications  Most common risk is IOP spikes in about 3–5% of patients  Iritis  Peripheral ant.synechiae  Hemorrhage  Corneal complication  Waning of response
  44. 44. Comparison  ALT maintained IOP control in 67–80% of eyes for 1 year, in 35– 50% for 5 years, and in 5–30% for 10 years (i.e., an attrition rate of 6–10% per year).  With SLT, IOP lowering occurs within 1–2 weeks; IOP lowering can continue for up to 4–6 months post-treatment and also continues for 3–5 years with a similar attrition to ALT Shingleton B.J., Richter C.U., Belcher C.D., et al: Long-term efficacy of argon laser trabeculoplasty. Ophthalmology 1987; 94:1513-1518 Weinand F.S., Althen F.: Long-term clinical results of selective laser trabeculoplasty in the treatment of primary open angle glaucoma. Eur J Ophthalmol 2006; 16:100-104.
  45. 45. Lasers in malignant glaucoma  Argon laser  Power :200–800 mW  Duration :0.1 second  spot size :100–200- μm.  This may restore the normal forward flow of aqueous, especially when accompanied by aggressive cycloplegic, mydriatic, and hyperosmotic therapy  The Nd:YAG beam is directed at the anterior hyaloid face between the ciliary processes using a single burst at power settings used for posterior capsulotomy.
  46. 46.  In aphakic ciliary block glaucoma the Nd:YAG laser can rupture the vitreous face and break the block.  Pseudophakic ciliary block glaucoma can also be treated with a Nd:YAG laser by rupturing anterior hyaloid .  Rupture of the posterior capsule may be needed to break the block in some cases
  47. 47. Cyclophotocoagulation  Reduce aqueous production by destruction of ciliary epithelium  Techniques  Transscleral  Transpupillary  Endolaser  Indication  Failure of multiple filtering surgeries  Primary procedure to alleviate pain in neovascular glaucoma with poor visual potential.  Painful blind eye  Surgery not appropriate
  48. 48. Cyclophotocoagulation  Trans-scleral cyclophotocoagulation  destroys ciliary epithelium and associated vasculature  decreased aqueous humor production.  Nd:YAG laser –  good scleral penetration  light energy is absorbed by blood and pigment of the ciliary body.  Diode laser (810 nm) has lower scleral transmission than the Nd:YAG laser (1064 nm) but greater absorption by melanin.  So use of 50% less energy compared to the continuous wave Nd:YAG laser to achieve the same effect
  49. 49. Cyclophotocoagulation  Trans-scleral Cyclophotocoagulation  Noncontact Nd:YAG laser cyclophotocoagulation  Contact Nd:YAG laser cyclophotocoagulation  Semiconductor diode laser trans-scleral cyclophotocoagulation  Endoscopic cyclophotocoagulation
  50. 50. Cyclophotocoagulation  Noncontact Nd:YAG laser cyclophotocoagulation  Nd:YAG laser is mounted on slit-lamp  4–8 J/pulse,  duration :20 ms  placed 1.0–1.5 mm posterior to the limbus total of 30–40 spots  3 and 9 o’clock positions spared to avoid long posterior ciliary arteries  A contact lens may be used to blanch blood vessels to improve the focus  Atropine 1% and prednisolone acetate 1% are prescribed four times a day; these are tapered as inflammation subsides.
  51. 51. Cyclophotocoagulation  Contact Nd:YAG laser cyclophotocoagulation  Nd:YAG laser in the continuous mode via a fiber optic system in direct contact with the conjunctiva  The fiber optic laser probe is positioned perpendicularly on the conjunctiva with the anterior edge 0.5–1.0 mm posterior to the surgical limbus.  power level of 4–9 W and duration between 0.5 and 0.7 seconds
  52. 52. Cyclophotocoagulation  Semiconductor diode laser trans-scleral cyclophotocoagulation  most widely used method of ciliary ablation with reported success rates ranging from 40% to 80%.  it is semiconductor diode laser (wavelength 810 nm)  1500–2500 mW for 1.5–3 seconds and a total of 18–24 spots
  53. 53. ENDOSCOPIC LASER CYCLOPHOTOCOAGULATION
  54. 54. ENDOSCOPIC LASER CYCLOPHOTOCOAGULATION  Performed with an 810 nm diode laser  Xenon light source that provides illumination and a helium-neon laser aiming beam  starting settings are 0.25 W with continuous exposure time.  The actual time of exposure is based on visual effect of ciliary process shrinkage and whitening  Typically, as much of the ciliary process is treated as possible, as there is a significant portion posteriorly that is usually not treated  cycloplegics are not necessary and steroids are used in the usual postoperative dosing
  55. 55. Comparison
  56. 56. Complications  Conjunctival burn  Hyphema  Inflammation  Pain  IOP spike  Cataract  Pupil abnormality  Hypotony  Need for re-treatment  Loss of visual acuity  Vitreous hemorrhage  Choroidal detachment  Phthisis
  57. 57. CO2 Laser Assisted Sclerectomy Surgery  Similar to trabeculectomy  Major difference being that after the scleral flap is raised, the remaining sclera over the Schlemm’s canal and trabecular meshwork is dissected by the CO2 laser probe until aqueous percolated over the entire dissected bed.  Aimed to prevent intra ocular complications.  Performed under sub-conjunctival anesthesia.
  58. 58. CO2 Laser Assisted Sclerectomy Surgery
  59. 59. Drawbacks  Demands careful and delicate surgery  Relatively long learning curve  Can be performed only by highly skilled surgeons,
  60. 60. Laser suture lysis  Subconjunctival trabeculectomy flap sutures can be lysed with the laser postoperatively if there is inadequate filtration  Dark nylon or proline sutures can usually be severed with the argon laser  settings of 200–1000 mW for 0.02–0.15 second with a 50–100-μm spot size  feasible from about 3–15 days after surgery or up to at least 2 months or more after mitomycin-C use Singh J, et al: Enhancement of post trabeculectome bleb formation by laser suture lysis, Br J Ophthalmol 80:624, 1996.
  61. 61. Method Laser suture lens. The device has a small convex lens that compresses the edematous conjunctiva permitting a clear view of the tiny nylon suture underneath the conjunctiva. This suture then can be cut easily with a 50-μm spot laser beam using 400 mW of energy for 0.1 second. (Photo courtesy of John Hetherington Jr, MD, University of California, San Francisco.)
  62. 62.  Dense hemorrhage in the tissues overlying the suture will absorb the energy, prevent treatment, and possibly cause conjunctival perforation.  fluorescein-stained conjunctiva limits argon laser energy transmission to the sutures and may cause conjunctival perforation.  thick, inflamed Tenon’s capsule may also preclude successful LSL  After laser steroid is given to reduce external scarring  Additional suture can be lysed 1-2 days after
  63. 63. Reopening of failed filtration site  Filtering sites can close because of fibrosis on the external side  Membrane formation or iris incarceration on the internal side of the sclerostomy  Argon or Q-switched Nd:YAG laser can vaporize it With the argon laser, settings of 300–1000 mW at 0.1–0.2 second with a 50–100-μm spot  The Nd:YAG laser is also useful in opening an obstructed sclerostomy  Single bursts of 2–4 mJ are delivered via a Nd:YAG coated goniolens to disrupt any translucent membrane obstructing it. Kandarakis A, et al: Reopening of failed trabeculectomies with ab interno Nd:YAG laser, Eur J Ophthalmol 6:143, 1996.
  64. 64. Femto laser in the offing  Applications for the femto laser ab externo include  Creating trabeculectomy flaps,  Non-penetrating procedure flaps,  Near-perforating deep excisions under flaps,  Removal or thinning of trabecular meshwork and the inner wall of Schlemm’s canal, and creating suprachoroidal fistulae
  65. 65. Excimer Laser  ab interno procedures include  ELT (excimer laser trabeculostomy) equivalent using docked gonio lens delivery systems  To Create full thickness or near full thickness scleral windows for trabeculectomy  To create suprachoroidal fistulae.
  66. 66. Cyclodialysis and laser  Cyclodialysis clefts have been both opened and closed with laser  Argon laser photocoagulation using thermal burns of 0.1 second 100-μm spot size, and 500 mW can be used to close cyclodialysis clefts and reduce hypotony  Nd:YAG is used to open cleft. Closure of a cyclodialysis cleft. The beam is aimed deep into the cleft to create an inflammatory response and generate closure. Postoperative mydriasis and cycloplegia may aid this process.
  67. 67. Laser synechiolysis  The argon laser can be used to pull early or lightly adherent peripheral anterior synechiae away from the angle or cornea.  (400–800 mW, 0.1–0.2 second,50–100-μm spot size  It is simillar to iridoplasty  Helpful to break and arrest formation of iridocorneal adhesions after penetrating keratoplasty or other forms of peripheral anterior synechiae.  Chronic synechiae can be very resistant to argon iridoplasty.
  68. 68.  The Nd:YAG laser can lyse iris adhesion.  Use- early irido–corneal–endothelial (ICE) syndrome to disrupt synechiae,  Side-effect is bleeding.
  69. 69. Goniophotocoagulation  Use - anterior segment neovascularization  Goniophotocoagulation is useful to obliterate fragile vessels in a surgical wound like in cataract incisions or trabeculectomy or goniotomy wounds  Argon laser 100-μm spot size for 0.1–0.2 second and 300–500 mW of energy will usually obliterate these vessels  Bleeding is common,  Gross hyphema may occur
  70. 70. Other uses of lasers  Goniopunctures in NPGS is mandatory, after a while, as during the surgical procedure itself, the AC is left alone.  Goniopunctures are done with a YAG Laser  These help passage of aqueous into the scleral lake.  Blocked inner ostium can be freed by Yag Laser, post trabeculectomy.  Vitriolysis , in case of a vitreous tag sticking out, can be done using a YAG laser.  Modifying bleb by lasers after staining the bleb with gention violet.
  71. 71. Goniopuncture Lasering the bleb
  72. 72. Lasers in Glaucoma - Summarizing  Lasers in glaucoma are an important part of the armamentarium in the management.  Several situations exist when laser therapy may prove beneficial to the control of intraocular pressure, in association with medical therapy and may enhance quality of life by preserving visual function.

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Lasers in Glaucoma, Dr.Parth Satani, Dr.Rita Dhamankar, Laxmi Eye Institute

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