This document discusses the use of lasers in the treatment of glaucoma. It begins by introducing different types of lasers used, including Nd:YAG lasers. It then covers specific laser procedures for glaucoma such as laser iridotomy to relieve pupillary block, laser iridoplasty to modify the iris, and laser trabeculoplasty to increase outflow. It compares argon laser trabeculoplasty to selective laser trabeculoplasty. The document also discusses laser techniques for angle closure glaucoma, post-operative treatment, and cyclophotocoagulation to reduce aqueous production. Throughout, it provides details on laser parameters and outcomes of these procedures.

1. Lasers in Glaucoma
Presenter:Dr.Parth Satani
Moderator:Dr.Rita Dhamankar

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. Lasers used in glaucoma
 488 - 514 nm - Argon blue-green & green
 810 nm Diode
 1064 nm - Nd:YAG
 10,600 nm - Carbon dioxide

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. 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.  Photoablation:
 breaks the chemical bonds that hold tissue together,
essentially vaporizing the tissue

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. Lasers in Open angle glaucoma
 Outflow enhancement
 Laser trabeculoplasty
 Inflow reduction
 Cyclophotocoagulation(for end stage disease)

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. Lasers in Post-operative treatment
 Laser suture lysis
 Adjacent to trabeculectomy
 Laser sclerostomy
 Laser gonio-puncture
 Adjacent to non-penetrating surgery

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.  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.

14. 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.

15. 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

16. indication
 Definitive indications
 Acute angle closure.
 Chronic (creeping) angle closure
 Mixed mechanism glaucoma
 Phacomorphic with an element of pupillary block
 Iris bombé

17.  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

18. Types of laser
 Photodisruptive Nd:YAG laser,(Q-switched and mode-lock)
 The photothermal argon lasers

19. 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

20. 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.

21. 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

22. Laser Iridotomy - position

23. 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

24. 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

25. 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.

26. 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

27. 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.

28. Complications
 Intraocular Pressure Spikes
 Laser-Induced Inflammation
 Iridectomy Failure
 Diplopia
 Bleeding
 Lens Opacities
 Corneal Injury

29. 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

30. Laser Iridoplasty
Note the almost
Ring like burns for laser
iridoplasty

31.  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

32. 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

33. Contraindications
 Contraindication
 Advanced corneal edema or opacification
 Flat anterior chamber
 Synechial angle closure
 Complication:
 mild iritis
 Corneal endothelial burn
 Transient rise in IOP

34. Laser trabeculoplasty
 Relatively effective,non-invasive.
 Laser treatment to trabecular meshwork increase to
increase outflow.

35. 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.

36. Laser trabeculoplasty
 Method
 Argon laser trabeculoplasty
 Selective laser trabeculoplasty
 Lens
 Goldmann 3 mirror lens
 Latina trabeculoplasty lens:

37. 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.

38. 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

40. 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

41. Selective laser trabeculoplasty (arrow) versus argon laser trabeculoplasty
treatment (arrowhead). (Courtesy of M. Berlin, MD.)

42. 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

43. Indications
 Chronic open angle glaucoma
 Exfoliation syndrome
 Pigmentary glaucoma
 Glaucoma in aphakia or pseudophakia

44. Contraindications
 Closed or extremely narrow angles
 Corneal edema
 Aphakia with vitreous in ant.chamber
 Vascular glaucoma
 Acute uveitis
 Primary congenital glaucoma
 Angle recession glaucoma

45. Complications
 Most common risk is IOP spikes in about 3–5% of patients
 Iritis
 Peripheral ant.synechiae
 Hemorrhage
 Corneal complication
 Waning of response

46. 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.

47. 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.

48.  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

49. 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

50. 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

51. Cyclophotocoagulation
 Trans-scleral Cyclophotocoagulation
 Noncontact Nd:YAG laser cyclophotocoagulation
 Contact Nd:YAG laser cyclophotocoagulation
 Semiconductor diode laser trans-scleral cyclophotocoagulation
 Endoscopic cyclophotocoagulation

52. 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.

53. 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

54. 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

55. ENDOSCOPIC LASER
CYCLOPHOTOCOAGULATION

56. 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

57. Comparison

58. 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

59. 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.

60. CO2 Laser Assisted Sclerectomy
Surgery

61. Drawbacks
 Demands careful and delicate surgery
 Relatively long learning curve
 Can be performed only by highly skilled surgeons,

62. 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.

63. 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.)

64.  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

65. 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.

66. 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

67. 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.

68. 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.

69. 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.

70.  The Nd:YAG laser can lyse iris adhesion.
 Use- early irido–corneal–endothelial (ICE) syndrome to disrupt
synechiae,
 Side-effect is bleeding.

71. 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

72. 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.

73. Goniopuncture
Lasering the bleb

74. 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.