The document discusses various retinal laser treatments used in ophthalmology, including pan retinal photocoagulation for conditions like diabetic retinopathy and retinal vein occlusions. It describes the different types of lasers and laser delivery systems, factors affecting retinal photocoagulation, and protocols for treating various fundus disorders. The laser treatments are aimed at reducing neovascularization, macular edema, and the risk of vision loss.

1. Retinal Lasers in Ophthalmology
Dr. Atul Dhawan (M.S., F.E.R.C.)
Vitreo-Retina Consultant
Dr. Agarwal’s Retina Foundation
Chennai

2. INTRODUCTION
LASER is an acronym for:
• L : Light
• A : Amplification (by)
• S : Stimulated
• E : Emission (of)
• R : Radiation
Term coined by Gordon Gould.
Lase means to absorb energy in one form and to emit a new form of
light energy which is more useful.

3. Gordon Gould [1959]

4. The Electromagnetic Spectrum

5. Incandescent vs. Laser Light
1. Many wavelengths 1. Monochromatic
2. Multidirectional 2. Directional
3. Incoherent 3. Coherent

6. These three properties of laser light are
what can make it more hazardous than
ordinary light. Laser light can deposit a
lot of energy within a small area.

8. Two things to produce laser
1. Population inversion
2. Stimulated emission

9. Stimulated emission
• Suppose an electron is in a higher energy level and a photon comes along
with an energy equal to the difference between the electron's energy and
a lower energy. What will happen is that the photon will stimulate the
electron to fall into the lower energy state, thereby emitting a photon.
This is pictured below.
• The emitted photon will have the same energy as the original photon, and
viewed as waves we will then have two waves emerging from the atom in
phase with the same frequency. Such waves will constructively interfere,
leading to a more intense wave.

11. Types of Lasers
LASERS
Gas Solid State Metal EXCIMER Dye Diode
Vapour
Argon Ruby Copper Argon Fluoride
Krypton Nd Yag Gold
Helium
Neon
Carbon Dioxide

12. Factors effecting retinal
photocoagulation
• Degree of scattering
• Absorption of energy by ocular pigments
• Spot size
• Power used
• Exposure time

13. Ocular pigments
• Melanin:
 RPE, Choroid
 Argon Blue, Krypton
 Pan Retinal Photocoagulation
 Haemoglobin:
 Absorb blue,green and yellow but poor for red light.
 Argon Green are absorbed, Krypton yellow. These laser are
found to be useful to coagulate the blood vessels.
• Xanthophyll:
 Macular area
 Maximum absorption is blue

14. Laser effects
LASER
TISSUE
Thermal Photo- Ionizing Effect
Effect chemical
 Photocoagulation  Photoradation
 Photoablation
. Photovaporization

15. THREE BASIC LIGHT TISSUE INTERACTIONS
(1) Photocoagulation:
Laser Light
transfer energy
Target Tissue[absorption by ocular pigments]
Generate Heat[transfer to tissue by thermal conduction]
Denatures Proteins
(Coagulation)
Rise in temperature of about 10 to 20 0C will cause coagulation of tissue.

16. PHOTOCHEMICAL EFFECT
PHOTORADIATION :
• Hematoporphyrin Derivatives administerd i.v. are selectively taken
up by metabolically active tissue
. subsequently irradiated by rhodamine dye laser[630 nm] 72 hours
injection .
This leads to formation of singlet oxygen which is cytotoxic.
e.g. Treatment of ocular tumour and CNV

17. THREE BASIC COMPONENTS
A Laser Exciting Optical Cavity
Medium Methods (Laser Tube)
• e.g. Solid, • for exciting • around the
Liquid or Gas atoms or medium
molecules in which act as
the medium a resonator
e.g. Light,
Electricity

19. MODES OF LASER OPERATION
Continuous Wave • It deliver their energy in a
(CW) Laser: continuous stream of photons.
• Produce energy pulses of a few
Pulsed Lasers: tens of micro to few mili second.
Q Switches • Deliver energy pulses of extremely
Lasers: short duration (nano second).
A Mode-locked • Emits a train of short duration
Lasers: pulses (picoseconds).

21. Laser delivery system
• SLIT LAMP
• LASER INDIRECT OPHTHALMOSCOPE
• ENDOLASER

22. Lenses for laser

23. PRP Lens
Image magnification: 1.96
FOV : 165 degree
LSMF: 0.51

24. VOLK AREA CENTRALIS
IImage magnification: 1.05
LSMF : 0.95
FOV : 82 degree

25. CLASSIFICATION OF CHORIORETINAL BURN
INTENSITY
• Light : Barely visible retinal blanching
• Mild : Faint white retinal burn
• Moderate : Opaque dirty white retinal burn
• Heavy : Dense white retinal burn

26. Pan Retinal Photocoagulation

27. LASER TREATMENT OF
FUNDUS DISORDERS
• Diabetic Retinopathy
• Retinal Vascular Diseases
• Choroidal Neovascularization (CNV)
• Eales disease
• Central Serous Retinopathy (CSR)
• Retinal Break/Detachment
• Tumour

29. India-Diabetic capital of the world
INCIDENCE BETWEEN 20-79 YRS HAS GONE UP 6 FOLD
IN THE LAST DECADE
Year
No. of people
2006
41 millions
2025
80 millions
Data Source
Dr J Brown,Chair,IDF Task Force

30. DIABETES CHALLANGE
EVERY ONE KNOWS SOMEONE
WHO HAS DIABETES.
“IT IS THAT COMMON IN INDIA”

31. Diabetic retinopathy
TYPE OF RETINOPATHY THERAPY
Maculopathy
Focal photocoagulation
CSME
Diffuse leakage around macula Grid laser
Circinate Focal photocoagulation
Pre-proliferative Retinopathy Frequent review
Proliferative retinopathy Pan retinal photocoagulation
Vitreoretinal surgery with
Advanced diabetic eye disease
photocoagulation

32. How it works?

35. Diabetic macular oedma
LEAK
DIFFUSE MIXED FOCAL
SRF/
NSD
IVTA MODIFIED
GRID FOCAL TO MA
,ANTIVEGF GRID
Periodic Periodic
FFA,OCT after
evaluation evaluation 2-3
4wks
3mths mths

36. ETDRS PROTOCOL
Focal Grid.
• 50 to 100u size 50 to 200u size.
• 0.05 to 0.1sec. 0.05 to 0.1 sec.
• Moderate intensity. Light to medium int
( mild RPE whitening)

38. Pan retinal photocoagulation
comprises of :
1. 2000-3000 application
2. in a scatter pattern of
3. 500 size with goldmann lense and 200-300
m size with panfunduscopic lens.
4. duration 0.05-0.10 sec.

39. Retinal Vein Occlusion

40. Introduction
Vascular obstructive disease of retina is a common vascular disorder, second only to
Diabetic Retinopathy in incidence
RVO
Central retinal vein Branch retinal vein
obstruction obstruction
Ischemic non ischemic

41. Venous Occlusion Causes elevation of
venous and capillary pressure
Stagnation of blood flow
Hypoxia of involved retina
Damage of capillaries endothelium
Extra vasation of blood
More pressure
Further more stagnation
Viscous cycle starts

42. C.R.V.O Study
Qn. What is the natural history of eyes with
perfused CRVO (<10 DD CNP areas) ?
Ans. 1/3rd of eyes with perfused CRVO became non-
perfused by 3 years
Majority of eyes classified as indeterminate
were non-perfused

43. C.R.V.O Study
Qn. Does early PRP prevent NVI in non-
perfused CRVO (>10 DD area CNP) ?
Ans. Prophylactic PRP does not prevent
Neovascularisation of iris or angle
Careful monitoring of INV/ANV and prompt PRP
is needed

44. C.R.V.O Study
Qn. Does early PRP is more effective than delaying
the Tt until ant. Segment neovascularization is
first seen in preventing NVG?
Ans. NO

45. C.R.V.O Study
Qn. Does macular grid PHC improve V.A. in
macular oedema due to perfused macular
edema ?
Ans. Grid PHC not recommended in perfused
macular oedema.

46. PRP Protocol
• 500 or 1000 µ size, duration 0.2 sec
• Burns 0.5 – 1 burn width apart
• More than 2 DD from center of the fovea till equator
or beyond in all quadrants, nasally >500 µ from disc
• Around 2000 spots
• Avoid retinal hemorrhages or large retinal vessels

47. Treatment Recommendations –
Non-perfused CRVO
Nonperfused CRVO Nonperfused CRVO with TC-INV
without INV/ANV or any ANV
Panretinal
PHC
No PRP unless monthly follow
up not possible Follow up every 2-4weeks
If INV/ANV increases
Supplemental panretinal
PHC

48. Neovascularisation B.R.V.O
In BRVO
• Areas of CNP >5DD
(NVD or NVE : first 3 yrs)
– 60% do not develop NVE
• 40% develop : NVE
• 60% of NVE Vit. hge

49. • For this reason it is recommended that laser
photocoagulation should be delayed till NVE
develops.

50. B.R.V.O
Recommendations
1. Vision 20/40 or less
2. Wait for 3-6 months: Clearance of Hges : Good FFA
3. Evaluation of FFA: Macular oedema Vs Ischaemia
4. Recommend grid treatment : Macular oedema FFA
proven
5. Macular Non perfusion : No laser

51. Eale’s Disease
HENRY EALES – 1980

52. Etiopathogenesis
• Unknown
• Factors - Tuberculosis
- Focal sepsis
- Berger’s disease
- Leprosy
- Brusellosis
- Sarcoidosis
- Behcet’s disease

53. Clinical features
SIGNS –
1. Inflammation
- Venous dilatation, tortuosity of veins
- Perivascular exudates, sheathing
- Superficial retinal haemorrhage
- Cells in vitreous, aqueous
- Keratic precipitates

54. Clinical features
2. Nonperfusion
- Intraretinal haemorrhage
- Collaterals around occluded vessels
- Microaneurysms
- A-V shunts
- Venous beading
- Hard exudates , cotton wool spots

55. Clinical features
3. Neovascularisation
- 10% Patients
- NVD
- NVE
- Rubiosis iridis
- Neovascular glaucoma

56. Clinical features
4. Other abnormalities
- Pigmentation – healed chorioretinitis
- Vitreous codensation, PVD
- Macular changes – Macular oedema
- Ischaemia
- Hole
- ERM

57. Management
AIMS - Reduce perivasculitis
- Reduce Vitritis
- Reduce chance of vitreous
haemorrhage

58. Management
1. Corticosteroids
2. Anterior Retinal Cryotherapy
3. Photocoagulation
4. Vitrectomy

60. Photocoagulation
• Flat new retinal vessel: direct laser to vessel
• Elevated neovascularization: laser the feeder
vessel
• NVD: Pan retinal photocoagulation
• Capillary non perfusion area: scatter laser

61. Central Serous Retinopathy

62. HISTORY
• First recognized by von Graefe in 1866
& named central recurrent retinitis
• Different names given by diff. persons
• ICSC given by Gass et al in 1967s

63. Idiopathic central serous
chorioretinopathy (ICSC)
• Patient is usually of Type A personality
• Organ transplantation , pregnancy
• Less common in high degree of myopia
• Young 20—50 yrs
• Male : Female 10 : 1 [ Age 30 – 50 yrs ]
• Male : Female 2 : 1 [ Age > 50 yrs ]
• WHITE > BLACK

64. SYMPTOMS
• Sudden onset Blurring of vision
• Metamorphopsia, micropsia
• Seeing a dark patch (central scotoma )

65. Signs
• Ophthalmoscopy—circumscribed round
or oval area of retinal elevation at post. pole
, outlined by a glistening reflex
• Foveal reflex—Absent / attenuated

66. Central serous retinopathy ( CSR )

67. FFA
• Pin-points site of RPED & site of leakage of
serous fluid from RPE into SR space
• In 95% of cases one area of leakage of dye
are seen -INK BLOT APPEARANCE
• Only in 10% cases the classic “smoke
stack pattern” is seen due to convection
currents & high sp. gr. of SR exudate

68. FFA
• Majority of leaking sites are within 1 DD of
fovea, but foveola is affected in < 10%
• Incidence of leakage sites is greatest in
upper nasal quadrant >lower nasal >lower
temporal
• 25% of leaks in PM bundle

69. Smoke-stack appearance

70. Smoke-stack
appearance
Later dye passes into
subretinal space and Subsequent lateral spread
vertical ascend until entire area filled

71. FFA of CSR
Early hyperfluorescent spot Subsequent concentric spread until entire area filled
Ink-blot appearance

73. TREATMENT
• Laser Photocoagulation at the site of leak
destroying leaky vessels, debrides
diseased RPE, allows growth of healthy
RPE.
• Laser causes early recovery but final VA is
same.

74. Laser Photocoagulation
• Vn of less then 6/12
• Well defined leakage point on FFA atleast 500
micron from the fovea
• More then 4 month
• Recurrent CSR
• Bilateral CSR
• OCCUPATIONAL NEED of the Pt

75. AGE RELATED MACULAR
DEGENERATION

76. TYPES OF ARMD
• NON EXUDATIVE
– (dry / non neovascular)
– slowly progressive
– 90% of ARMD
• EXUDATIVE
– (wet / neovascular)
– less common
– 88% of legal blindness due to ARMD
Both may occur in combination

77. Exudative AMD
Drusen and AMD - progression
Atrophic AMD

78. Classical CNV
•Well defined memb. fills with dye in “LACY”
pattern in early phase, fluoresces brightly during
peak dye transit then leaks into subretinal space
and around CNV within 1—2 min
•Fibrous tissue of CNV stain to give late Hyperf.
•Subdivided into 3, with relation to foveola

79. Classical CNV
1. EXTRA-foveal >200 um from FAZ center
2. JUXTA-foveal <200 um from FAZ but
sparing the foveola
3. SUB-foveal Involving foveola either by
nearby extension or direct origin underneath
(70% of CNV extend to subfoveal position within 1 yr)

80. Occult CNV
• Poorly defined membrane gives late leakage
Occult divided into two By MPS
1. Fibrovascular RPED
2. Late leakage of fluorescein from
undetermined source

81. TREATMENT OF WET ARMD
1. Photocoagulation
2. Radiation therapy
3. TTT
4. TSDLP
5. Photodynamic therapy (PDT)

82. TREATMENT OF ARMD
6. Pharmacological agents
7. Micronutrients
8. Gene therapy
9. Foveal translocation/ Macular rotation
10. RPE / IPE cell transplantation

83. TREATMENT OF ARMD
1. PHOTOCOAGULATION
For complete oblitn of CNV
Focal—Extra, Juxta, selected subfoveal CNV
For recurrent CNV similar parameters
Argon Green laser(514 nm) recommended by
MPS. Diode infrared if covered by thin
haemorrhage

84. Disadvantages of laser T/t
• Only for well defined CNV
• Significant fall in VA depending on site
• High recurrence rates
• Benefit occurs after long period (months)
• Breach of Bruch’s membrane can trigger
similar pathgenesis as the ds. itself.

85. PHOTODYNAMIC THERAPY
• Photochemical injury to the target
• Drug is conc. in rapidly dividing cells & NV
tissue
• T1/2 of dye 5—6 hrs
• Excreted in stools (urine not discolored)

86. • Singlet oxygen & free radicals damage cellular
str. by platelet activation, vessel occlusion,
destruction of fibrovascular tissue

87. PDT
Photosensitizers— working at wave length
• Benzoporphyrin derivatives (vertiporfin)-690
• Tin ethyl etiopuritin (Purlytin)-664 nm
• Lutetiutexaphyrin (Lu-tex)-732 nm

88. Eligibility criteria for PDT
1. Lesions involving FAZ
2. Lesion size < 5400 um
3. CNV > 50% of the lesion
4. Classic component >50% of CNV
5. > 200 um from disc edge
6. VA 20/200—20/40

89. C/I of PDT S/E of PDT
Extravasation
• Allergic to the dye Rash
• H/O porphyria Headache
• Severe liver disease VA reduction
• Severe Heart disease Decreased fields
Dry eye
• Uncontrolled HT Conjunctivitis
Cataract
Hemorrhages

90. Procedure of PDT
1. 15 mg visudyne powder + 7 ml dist. water
2. Dark green soln (protect from light)
3. Store at 20-25o C, use within 4 hrs
4. Dose 6 mg/m2 . Dilute in 5% DNS to make 30
ml soln
5. Inject 3 ml/min over 10 minutes
6. Rinse IV line by 5 ml of 5% DNS
7. After 15 min (the vessels fill completely)

91. Procedure of PDT
8. Diode laser 689 nm
9. 50—60 J/cm2 at intensity of 600 mw/cm2
10. Duration—83 seconds
11. Spot size—GLD + 1000 um
(GLDgreatest linear dimension of lesion by
FFA)
12. Protective dark glasses, hat, clothing &
avoiding sunlight/bright light for 5 days