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1. LASERS IN RETINA Principles, Clinical Applications and Recent advances Moderator:Dr.Ravi.B Presenter:Dr. Sushma Presenter:Dr.Kavitha.L.T

2. OVERLAY Definition History Properties of Laser Types of Laser Components of Laser System, accessories (lens) Modes of Laser Output Clinical applications-DM retinopathy, Vein Occlusions, CSR, ROP , PDT, TTT Recent Advances

3. Definition L ight A mplification by S timulated E mission of R adiation Laser is a source of high intensity optical, infrared or ultraviolet radiation produced as a result of stimulated emission of photons, maintained within a medium, having same energy and phase (monochromatic and coherent) allowing it to be brought to a fine focus. Term coined by Gordon Gould. www.collinsdictionary.com

4. Early History 1620-1689 Theophilis Bonetus -medieval description central vision loss gazing sun 1867-Czerny- Retinal damage from sunlight 1917- Albert Einstein-Stimulated emission of Radiation 1949- Meyer Schwickerath- focussed sunlight on retina to treat melanomas. Only summer, other non solar source sought Saudi J Ophthalmol . 2015 Apr-Jun; 29(2): 137–146. Published online 2014 Sep 28. doi:  10.1016/j.sjopt.2014.09.001 PMCID: PMC4398802 PMID: 25892934 Modern retinal laser therapy Igor Kozak a,⁎ and Jeffrey K. Luttrull b

5. HISTORY OF LASER Invented in 1958 by Charles Hard Townes and Arthur Leonard Schawlow of Bell Laboratories.(Nobel prize in Physics 1964) • Was based on Einstein’s idea of the “particlewave duality” of light, more than 30 years earlier • Originally called MASER (m = “microwave”)

6. History 1956—Hans Littmann of Carl Zeiss Laboratories -Xenon-arc photocoagulator 1960—Theodore Maimon Hughes laboratories-Ruby Laser (694nm) 1964— William Bridges Argon Laser -blue 488nm , green 514nm (absorbed by Hb & melanin)

7. Ruby Laser Type to enter a caption.

8. PROPERTIES OF LASER Monochromatic -emit only one wave length Coherence -all in step with one another Polarized . - in one plane pass through media Collimated -i n one direction & non spreading High energy. - Intensity measured by Watt J/s

9. PROPERTIES OF LASER The light emitted from a laser is monochromatic , that is, it is of one color/wavelength. In contrast, ordinary white light is a combination of many colors (or wavelengths) of light. Nearly monochromatic light Example: He-Ne Laser λ0 = 632.5 nm Δλ = 0.2 nm Diode Laser λ0 = 900 nm Δλ = 10 nm Comparison of the wavelengths of red and blue light Monochromatic

10. Coherence Incoherent light waves Coherent light waves The light from a laser is said to be coherent , which means that the wavelengths of the laser light are in phase in space and time. Ordinary light can be a mixture of many wavelengths.

11. Polarization Polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization .

12. Conventional light source Divergence angle (θd) Beam divergence: θ d= β λ /D β ~ 1 = f(type of light amplitude distribution, definition of beam diameter) λ = wavelength D = beam diameter Lasers emit light that is highly directional , that is, laser light is emitted as a relatively narrow beam in a specific direction. Ordinary light, such as from a light bulb, is emitted in many directions away from the source. (Collimated) Unidirectional

13. LIGHT vs LASER Stimulated emission Monochromatic Highly energized Parallelism Coherence Can be sharply focussed. Spontaneous emission Polychromatic Poorly energized Highly divergence Not coherent Can not be sharply focused

14. Light consists of electromagnetic waves, emitting radiant energy in tiny package called ‘ quanta ’/ photon . Each photon has a characteristic frequency and its energy is proportional to its frequency. When light passes through certain materials, these photons excite electrons around the atoms into the next higher energy level. Two basic ways for photons and atoms to interact: Spontaneous Emission Absorption Stimulated Emission PHYSICS

15. Physics

16. Basic concepts for a laser Absorption Spontaneous emission Stimulated emission h n h n h n E 1 E 2 E 1 E 2 h n =E 2 -E 1

17. lasers Wavelength Krypton red 647 nm Krypton yellow 568 nm Frequency doubled 532 nm Nd YAG Argon green 514 nm Argon blue 485 nm Diode 680nm / 810nm TYPES OF OPHTHALMIC LASERS

18. Lasers used in our Institute Green 532nm—endolaser / SL single spot Red 810nm—LIO/endolaser Yellow 577nm—Micropulse multispot SL —single spot LIO

19. COMPONENTS OF A LASER SYSTEM 3 VITAL components Lasing medium Pumping source Optical Resonator 96%

20. 1.LASING MEDIUM Substances having the property to lase A collection of atoms/ molecules/ ions that emit radiation in the optical part of the electromagnetic spectrum. It may be a solid, liquid or gas Nature of the lasing medium determines the nature of the emitted radiation (wavelength /colour)

21. 2. PUMPING SOURCE A source of external energy that activates lasing medium Generates a stimulating photon which in turn causes stimulated absorption and population inversion. May be an electrical discharge, heat, flashlamp or ionising radiation.

22. 3.OPTICAL RESONATOR Amplifies the generated radiation and creates a much powerful beam. Consists of Brewester windows that allows passage of light to a pair of mirrors, one totally reflective and the other partially reflective. The no.of resonating cycles varies greatly amongst the various lasers.

23. MODES OF LASER OUTPUT CONTINUOUS OUTPUT: delivers energy in a continuous stream over a long time low power pumping source constant

24. PULSED OUTPUT modest amount of energy concentrated into very brief time high power intermittent pumping source Ex. Nd YAG, excimer laser Q Switched Lasers: pulses 4 nanoseconds Mode-locked Lasers: pulses 4 picoseconds

25. continuous wave laser used in intermittent timed manner. in between, laser output is gated GATED PULSE DELIVERY:

26. LASER DELIVERY Instrument based Ruby Laser (monoocular direct ophthalmoscope) Slit lamp (contact lens based) Laser indirect ophthalmoscope(LIO) (IDO based) Endolaser (fibre optic probe in eye) Camera based navigated retinal photocoagulation with eye tracking (NAVILAS) Selective targeted photocoagulation (recent advances) Routes Trans pupillary Trans scleral Interaction with ocular tissue Contact Non contact

27. LASER INSTRUMENTATION LASER Components are - • Console : It contain laser medium and tube, power supply and laser control system. • • • • Control Panel : It contain dials or push buttons or touch screen for controlling various parameters. Aiming Beam Laser Switch Safety Filter Delivery System •

28. LENSES PLANO-CONCAVE Upright image High resolution of small retinal area Mirrors angulated at 59º, 69º and 73º suitable for focal laser prototype: Goldman 3 mirror HIGH POWER CONVEX Inverted image Mild loss of fine resolution, but provide a wide field of view suitable for pan-retinal photocoagulation. prototype: Mainster PRP 165 Selection of laser setting parameters (spot size, power, duration) depends on the area of retina to be treated, clarity of media, and fundus pigmentation. Macular laser treatment usually requires spot size of 100 μ, low power setting.

29. ACCESSORY COMPONENTS Corneal Contact Lenses for Laser use Goldman style 3-mirror lens for photocoagulation (PRP) lenses Volk-Superquard and pan 165 for PRP Mainster and Area centralis for focal and grid laser Indirect Fundus Lenses (20 D & 28D) for Indirect laser delivery

30. With these lenses, the view is inverted and reversed, and these allow for a magnification of the size of the burn delivered. The spot size setting on the slit-lamp delivery system must take into account the magnification factor. Therefore, 200-300 μ is used and the retinal spot size comes to approximately 500 micron due to laser spot magnification factor(LSMF).

31. Disinfection of Lens Cleaning • Use mild cleaning solution—diluted liquid soap and water, or alcohol and wipe with a soft cotton cloth. Disinfection a. Glutaraldehyde 2% b. Sodium hypochlorite (10 parts H2O, 1 part bleach) Sterilization Ethylene oxide sterilization is recommended. (Never autoclave or boil lenses).

32. USING THE OPHTHALMIC LASER PREPARATION OF THE PATIENT FOR LASER Topical Anaesthetic Position of the patient at Slit Lamp THE SURGEON : Comfortable position at Slit Lamp Semi-darkened Room Appropriate Contact Lens

33. Slit lamp biomicroscopic laser delivery • Most commonly employed mode for anterior and posterior segment. • ADVANTAGES : • Binocular and stereoscopic view. • Fixed distance. Increased magnification • Standardization of spot size is more accurate. • Aiming accuracy is good. Lens keeps the eyelids open constantly

34. Laser indirect ophthalmoscope Advantages : • Wider field(ability to reach periphery). Better visualisation and laser application in hazy medium. • Ability to treat in supine position . Disadvantages : • Difficulty in focusing. • Difficulty to standardize spot size . • Expensive. • Un co-operative patient . • Learning curve.

35. Spot size increases with increase in Image plane Power of hand held lens Hyperopia Complications: Choroidal hemorrhage Injury to cornea/ iris/ lens/ iol

36. Endo Laser

37. TYPES OF OCULAR PIGMENT Effective retinal photocoagulation depends on • how well light penetrates the ocular media • how well the light is absorbed by pigment in the target tissue Ocular pigments HAEMOGLOBIN Absorbs wavelengths of shorter range (Blue and Green), and longer wavelengths are minimally absorbed. Hence, RED laser is used to treat across regions of hemorrhage.

38. Xanthophyll: Present in inner and outer plexiform layers, confined to fovea. Maximum absorption is blue. Yellow and red light are passed. Melanin: Present in RPE and Choroid Absorbs the entire range of visible spectrum , however less efficiently the lower infrared range. Argon Blue, Krypton yellow and ,double frequency YAG lasers used for Pan Retinal Photocoagulation, and Destruction of RPE

39. LASER TISSUE INTERACTION LASER VARIABLES : Wavelength Spot Size Power Density Duration TISSUE VARIABLES: Transparency Pigmentation Water Content

40. Laser Tissue Interactions

41. Photo coagulation Photo thermal phenomenon Pigment dependent Induces moderate sterile inflammation laser light on target tissue heating of the tissue temp raise: 10-20%C) tissue atrophy thrombus formation and collagen contraction Tissue atrophy beneficial in PRP Collagen shrinkage causes undesirable effect in a case of fibrovascular proliferation resulting retinal traction. However, it has a beneficial effect in peripheral iridoplasty Argon, Krypton, Dye, Diode, Frequency doubled YAG

42. Photo vaporisation Photo thermal phenomenon Pigment dependent laser light on target tissue Vaporization of tissue to CO2 and water(temp raise: 60-100 o C) Desirable effects in iridotomies , Femtolaser cataract sx. Undesirable for retinal pathologies, as they cause break in Bruch’s membrane and rupture of vessel wall resulting in hemorrhage.

43. Photo ablation Photo chemical Non pigment dependent Interaction at the molecular level Results in very clean edged incisions Basis of photorefractive and phototherapeutic keratectomy Excimer lasers [form of ultraviolet laser (193nm)] Risk of mutagenecity

44. Photo disruption Mechanical Effect Non pigment dependent Laser light Acoustic Shockwaves Plasma formation Tissue destruction Nd:YAG lasers typically emit light with a wavelength of 1064nm, in the infrared range. Used for posterior capsulotomy in capsular opacification and Peripheral iridotomy

45. Photo Dynamic therapy Predominant application is in malignancies Hematoporphyrins(verteporfin) injected intravenous, tag tumour cells low-power diode lasers (630 nm) Release of highly destructive singlet oxygen Destruction of tumour cells with sparing of surrounding normal tissue Choroidal melanomas have been succesfully treated.

46. Chorioretinal coagulation Grades STEP BY STEP LASERS IN OPHTHALMOLOGY JAPEE -Bikas Bhattacharya

47. Laser Beam

48. Laser Applications Iridotomy

49. Argon blue- green laser It is a mixture of 70% blue (488 nm) and 30% green (514 nm) light. Most commonly retinal photocoagulation & trabeculoplasty Photocoagulation aims to treat the outer retina and spare the inner retina to avoid damaging the nerve fiber layer Absorbed selectively at the RPE, Hemoglobin, choriocapillaries, layer of rods & cones and outer & inner nuclear layers. Readily absorbed by the melanin granules. Coagulates from RPE to nerve fiber layer Not used much due to more damage to nerve fiber layer as compared to db.freq.YAG green laser

50. Q Switching Nd:YAG produces 2 wavelengths, one in the infrared range (1064 nm) and the second beam of 532 nm wavelength which is useful for superficial skin lesions. Q-switching refers to the technique of making a high-intensity beam in very short pulses

51. Freq-doubled Nd:YAG laser • Produces a green beam. • Most commonly used laser • Often termed as “green laser” • Highly absorbed by Hb & the melanin pigment. • It coagulates from RPE to ONL. • It causes coagulation with least energy transmission & shows considerable safety in macular treatment also. In Q-switched mode, Nd:YAG produces 2 wavelengths, one in the infrared range (1064 nm) and the second beam of 532 nm wavelength which is useful for superficial skin lesions. Q-switching refers to the technique of making the laser produce a high-intensity beam in very short pulses

52. Krypton red laser • Melanin absorbs it readily. • It is not absorbed by xanthophyll & Hb and hence it is particularly suitable for macular photocoagulation. • Frequency 647 nm • It coagulates deeper into the RPE & choroids. It has insignificant effect on the vascular system of retina. • Disadvantage is that it is painful due to deeper penetration into choroid

53. Diode lasers It emits an infrared wavelength of 810nm/577nm It is absorbed only by melanin hence used for macular photocoagulation It also penetrates the sclera. Thus if retina is obscured from view through the pupil, coagulation may still be performed by placing the probe on the sclera. Used for grid laser, PRP, Transpupillary thermo therapy and Diode cyclophotocoagulation

54. Laser Hazards General complications Pain Seizures Anterior segment complications Elevated IOP Corneal damage Iris burns Crystalline lens burns IOL and PC damage Internal ophthalmoplegia

55. Complications Choroidal detachment and exudative RD Choroidal,subretinal and vitreous haemorrhage Thermal induced retinal vascular damage Pre retinal membranes

56. Complications Ischaemic papillitis Paracentral visual field loss and scotoma Photocoagulation scar enlargement Sub retinal fibrosis Iatrogenic choroidal neovascularisation Accidental foveal burns

57. Laser Safety Class 1—causing no biological damage Class 2—safe on momentary viewing but chronic exposure may cause damage Class 3—not safe even in momentary view Class 4—cause more hazards than class 3 LASER SAFETY REGULATION Pt safety ensured by correct positioning Danger to surgeon is avoided by safety filter system Safety of observers and assistants

58. Post Laser Advice AIM- Reduce/Control venous pressure rise Avoid sneezing, cough,constipation Do not lift heavy objects/ exercises Head level to be above heart during sleep

59. CLINICAL APPLICATION OF LASERS IN RETINAL DISORDERS

60. PRE LASER WORK-UP Components Basic work up Selection of type of Lenses and Anaesthesia Patient counselling

61. BASIC WORK UP Detailed history Recording of the uncorrected and best-corrected visual acuity Anterior segment evaluation - FBs, KPs on endothelium, decompensation of cornea—decrease effectiveness - Cells/ flare/ blood in anterior chamber —decreases the visualization and also effectiveness. -Minimum pupillary diameter of at least 4-5 mm -Nuclear cataract — reflect the beam in various directions, therefore, a distinct focus cannot be attained

62. Vitreous examination • Opacities like blood clots/pigments/membranes—decrease effectiveness • If the area to be lasered is not seen clearly by indirect ophthalmoscopy, then no laser may be possible • Avoid pigment clumps, glial proliferation and membranes (because their treatment increases traction) Retinal evaluation • Retinal edema can result in increased energy requirement. • Hemorrhages lead to severe scarring due to excessive heat production • Avoid large/ blot/ deep hemorrhages Color photography • For documentation and academic purposes

63. Generally done under topical anaesthesia. The laser wavelength used often, helps to decide the type of anesthesia required. Infrared diode laser tr eatment (810 nm wavelength) often causes pain and may sometimes require a peribulbar block to obviate the pain ANAESTHESIA

64. PATIENT COUNSELLING Details of photocoagulation procedure Expected results and possible complications Explain that the laser is being done to arrest the progress of disease and help to maintain vision. Possibility of temporary or permanent visual loss, despite laser treatment. Number of treatment sittings. Specific questions asked by the patient should be carefully answered. Patient/Relative should be asked to sign a consent form that explains the purpose and scope of treatment.

65. Mydriasis-maximum pupillary dilatation using Tropicamide(1%) & Phenylephrine(5%) Anaesthesia- Topical Proparacaine Hcl(0.5%) Comfortable Sitting for both- Patient & Doctor Steady Fixation of head using head strap

66. LASER MANAGEMENT OF DIABETIC RETINOPATHY Photocoagulation has remained the only established non-invasive mode of treatment for diabetic maculopathy and proliferative retinopathy. The argon blue-green has been traditionally used, though more recently solid state frequency-doubled 532 nm YAG (green) lasers is used.

67. MECHANISM OF ACTION OF LASER PHOTOCOAGULATION In Proliferative Retinopathy Direct destruction of neovascular complex. Destruction of hypoxic/ ischemic area that produces vasoproliferative factors. Convert hypoxic retina to anoxic retina thereby more retinal blood is available to nourish the remaining retina. Decreased oxygen requirement of inner retina. Produce chorioretinal adhesion that resists against vitreo-retinal traction force.

68. Indications (HRC) Mild NVD, if associated with pre retinal or vitreous haemorrhage. **NVE (at least 1/2 disc areas in extent),if associated with pre retinal or vitreous haemorrhage. Other accepted indications; Rubeosis of iris and/or anterior chamber angle(irrespective of presence or absence of high risk characteristics. Eye with features of extensive retinal ischaemia i.e., retinal haemorrhages, capillary non perfusion and soft exudates. Patients with severe proliferative diabetic retinopathy (PDR) in the other eye.

69. Indications cont… In one eye where both eyes are approaching high risk proliferative stage. High risk proliferative stage. In pregnancy or after renal transplantation in patients with severe pre-proliferative diabetic retinopathy(PPDR) or proliferative diabetic retinopathy(PDR) even without high risk charatersitics. Contraindications Eyes with mild to moderate non-proliferative diabetic retinopathy (NPDR). Relative contraindication-If proliferative diabetic retinopathy coexists with clinically significant macular edema(CSMR) either focal or grid laser treatment of CSMR is done first followed by PRP 4-6 weeks later.

70. Panretinal photocoagulation Single spot Intensity—mod burn (150-250 mW) Duration—100ms Spot size—500μm Spacing—1 burn width Extent—major arcades to equator or anterior-500μm to disc nasally, 3000μm from centre of macula temporally Laser lesion—immediate greyish white mark Sittings—1200-1600 burns over 2-3 sessions Laser—532nm Nd-YAG or Argon Green Inferior half of the retina is photo coagulated first

71. Fundus photo showing scatter laser for diabetic retinopathy

72. PRP results in regression of NVD and and minimizes the risk of vitreous hemorrhage and later traction retinal detachment. Persistent NVD require fill-in treatment and this is extended more peripherally usually with the Goldmann 3-mirror lens or laser indirect ophthalmoscopy (LIO). Persistent or fresh NVE can also be treated with confluent laser burns. Post-PRP regressed NVE

73. Add on Lasers

74. Complications of PRP

75. Complications of PRP

76. FOLLOW UP The first routine follow-up visit is scheduled for 4-6 weeks following the completion of the PRP. Supplemental treatment (usually only after 6-8 weeks of completion of PRP) is recommended

77. ETDRS guidelines for F/U

78. DIABETIC MACULOPATHY Photocoagulation treatment is performed for macular thickening. This is often best picked up subjectively by a careful +90D or +78D Slitlamp biomicroscopic examination or more so objectively by the OCT. FFA and OCT values should be obtained in an effort to delineate the macular perfusion (and rule out macular ischemia) and guide the treatment pattern planned.

79. MECHANISM OF ACTION OF LASER PHOTOCOAGULATION In Macular Edema It appears to repair RPE cells. Reduces oxygen consumption by destroying the highly metabolically active outer retinal cells. Increasing oxygen diffusion from choroidal circulation. Preventing leakage by directly coagulating the leaky walls of microaneurysms. Induces endothelial cell division in the inner blood retinal barrier.

80. The pathway where laser photocoagulation acts in diabetic retinopathy

81. GRID PATTERN laser photocoagulation is employed generally; 50-200μm burns of light intensity with 100ms duration and 100 mW are placed 1 spot apart staying 500 μ away from the foveal center and the disc margin to upto 3000 μ from macular center. Modified macular grid (usually performed) excludes the area of the papillomacular bundle. Modified C grid laser in an eye with diabetic maculopathy

82. FOCAL Laser FOCAL TREATMENT of leaking microaneurysms , if indicated 500μm to 3000μm from centre of macula Conventional— 50-100μm spot, 0.1sec duration Argon green (514 nm or 532 nm) and yellow wavelengths ar e the preferred laser wavelengths for treatment of diabetic maculopathy. Focal laser in an eye with early CSME Focal laser around neovascular tuft

83. Adequate treatment of the maculopathy results in obliteration of the microvascular lesions, resolution of edema, absorption of hard exudates and stabilization or improvement of visual acuity. ADVERSE EFFECTS Inadvertent foveal burn Secondary choroidal neovascularization (inappropriately high laser power and small spot sizes close to the fovea leading to rupture of Bruch’s membrane). When maculopathy coexists with PDR it is better to treat macular edema and wait 4 to 6 weeks before panretinal photocoagulation. This reduces the risk of exacerbation of edema after panretinal photocoagulation.

84. Recent Advances PASCAL Targeted Laser Photocoagulation Micro pulse Laser Selective Retinal Therapy Subthreshold Diode micro pulse Laser NAVILAS

85. PASCAL(Multispot) Pa ttern sca n l aser uses microprocessor driven scanner with scalable patterns Multispots simultaneously in pre determined pattern Frequency doubled Nd YAG solid state Laser 532nm,20ms ,1800-2400 burns or Yellow laser 577nm ADV-Short time ,less damage, less pain, uniform spots, rapid learning time, single session DIS ADV-single session ,macular oedema ,exudative RD, CD, less efficacy

86. Pre determined Settings

87. Dis advantage of Pascal

88. Targeted Laser Photocoagulation Selective photocoagulation of areas of capillary non perfusion detected on FFA and abnormal perivascular leak and borders, feeder vessel photocoagulation in choroidal neovascularization, focal laser photocoagulation in the treatment of DME, Minimal complications, spare better-perfused areas from laser induced necrosis Takes care of ischaemic areas and resultant ME in Refractory cases Done with conventional laser or PASCAL

89. Micro-pulse laser Laser application sub threshold levels ,micro pulses Shorter than thermal relaxation time of RPE (0.1ms) Duty cycle low(5% of 0.2s) ,off time between pulses high Damage to RPE, photoreceptors, choriocapillaris spared No visible burns or scars VF changes reduced, improved macular sensitivity Infra red diode laser(810nm) or yellow laser(577nm)

90. Used in macular diseases, namely CSC, diabetic macular edema (DME), and retinal vein occlusion (RVO). Diode lasers 810 nm, near-infrared range of the spectrum.deep penetration into the choroid, but it is not clear if is relevant in micropulse treatment. Treatment near the foveal avascular zone, the 810-nm laser has the advantage that the laser energy will relatively spare the inner neurosensory retina and affect mainly the deeper layers Micro-pulse laser

91. Subthreshold diode micro pulse laser( SDM) “Subthreshold” refers to photocoagulation that does not produce clinical or histologic evidence of retinal damage. Micro pulsed laser parameter High Density / Low intensity RPE not damaged Transfoveal treatment Saudi J Ophthalmol . 2015 Apr-Jun; 29(2): 137–146. Published online 2014 Sep 28. doi:  10.1016/j.sjopt.2014.09.001 Adv Ther . 2017; 34(7): 1528–1555. Published online 2017 May 24. doi:  10.1007/s12325-017-0559-y

92. 810nm diode Micropulse

93. Yellow laser ,577nm, Micropulse treatment has the advantage that xanthophyll, the pigment which is located in the inner and outer plexiform layers of the macula, absorbs the yellow light only minimally so treatment near the fovea is relatively safe.

94. Selective retina therapy 1992 Reginald Bimgruber-shorter microsec continuous wave laser pulse Frequency doubled Nd:Yttrium Lithium Fluride, 527nm,1.7ms, 30 pulses per laser shot Laser gets absorbed by melanosomes in RPE Thermo-mechanical disruption with micro bubble formation Stimulates migration and proliferation of RPE In vascular leakage areas, seals leaking retinal barrier Photoreceptors and choriocapillaries not affected

95. NAVILAS (Inc. Germany) uses retinal navigation and fundus camera based delivery. This 532-nm pattern-type eye-tracking laser integrates live color fundus imaging, red-free and infra-red imaging, fluorescein angiography with photocoagulator system. After image acquisition and making customized treatment plans by physicians including marking areas which will be coagulated the treatment plan is superimposed onto the live digital retinal image during treatment. The physician controls laser application and the systems assist with prepositioning the laser beam. In accuracy of laser delivery, it significantly outperformed conventional laser photocoagulation with 96% of laser applications being delivered within 100 μm from the target spot. This platform allows for digital documentation of treatment for future reference. For the first time physicians are able to deliver fast and painless laser through camera system and monitor treatment progress on wide screen. Retinal navigation has resulted in significant increase in treatment accuracy in comparison to conventional slit-lamp lasers.

96. Retinal Regeneration Therapy(2RT) Subthreshold Laser with Micropulse laser, 532nm, 3- nano second pulses Stimulates renewal of RPE, Treatment without damage to opposed tissues Sublethal injury to targeted RPE ,rather than destroying Cytokine release by recovering RPE

97. End Point Management Programme for 577 pascal laser Mapping tissue damage values to laser energy Defining laser power at 20ms pulse duration to produce barely visible burn within 3 sec of laser pulse This energy level is defined as 100% ,all others are expressed as percentage of this titration threshold

98. PETER PAN study AIM- To investigate short term effects of high density 20-ms laser on macular thickness using Pascal- TRP(targeted) and reduced fluence/ minimally traumatic PRP (MT-PRP) compared to standard intensity (SI-PRP) in PDR CONCLUSION High density 20ms pascal TRP and MT-PRP using 2500 burns did not produce increase macular thickness or any ocular adverse events during short term

99. LASER TREATMENT IN VENOUS OCCLUSIONS Branch and central vein occlusion represent the second most frequent cause of retinal vascular disturbance, after diabetic retinopathy. The amount of visual and retinal damage is related to the geographic area drained by the occluded vein, the extent of occlusion, and the ability of the surrounding vessels to develop collaterals.

100. BRVO The two most significant vision-threatening complications of branch vein occlusion are macular edema and retinal/ optic disc neovascularization.

101. Indications 1. Grid Laser —Persistent macular edema responsible for ≤ 6/12 (or 20/40) vision with intact perifoveal capillary network, late accumulation of flouroscein at the fovea, in BRVO of at least 3 months duration. 2. Scatter/PRP —Retinal neovascularisation (NVE and or NVD), in BRVO of at least 3 months duration. Contraindications 1. Macular nonperfusion, i.e. ischemia demonstrated on FFA. 2. Reduced visual acuity due to RPE changes demonstrated on FFA.

102. Technique proper- GRID LASER-IN BRVO Parameters Exposure time—100msec. Spot size—100-200 μm Intensity of burn-light, 1 burn/spot size width apart Location and pattern—Same as for grid laser in diabetic maculopathy – The grid laser may extend upto the border of the FAZ i.e.; 500 μm from the macular center and from arcade to arcade. – Areas of capillary leak. – Areas of papillomacular bundle. – Areas of retinal hemorrhages avoided.

103. Technique Proper- Scatter/PRP-In BRVO Sectoral laser It may be done either in combination with grid laser or alone for treatment of NVE and or NVD. New vessels are found usually at the junction of the normal and ischemic retina. Parameters Exposure time—100msec. Spot size—200-500 μm Intensity of burn-moderate, 1 burn/spot size width apart. Location and pattern of scatter-Same as for scatter/PRP in diabetic retinopathy. Only the sector/segment of retina affected by capillary nonperfusion in BRVO.

104. Follow up schedule—Every 4 months 1st follow up-4 months post laser * FFA is a must in 1st follow up *If macular edema persists along with diminished visual acuity, additional grid photocoagulation may be considered. *If neovascularization persists or aggravates additional scatter laser may be considered. 2nd follow up-8 months post laser.

105. Sector laser in an eye with long standing superotemporal BRVO and macular exudates

106. CRVO In CRVO, the collaterals develop on the optic disc between the retinal and choroidal circulation. In ischemic CRVO, new vessels usually develop on the iris (NVI) and angle of the anterior chamber/trabecular meshwork (NVA). Timing of laser CRVO patients should be examined at monthly interval during immediate 6-month post CRVO period. Routine undilated slit-lamp examination and gonioscopy is a must to detect early new vessels iris (NVI) and angle of the anterior chamber/trabecular meshwork (NVA) in monthly check ups.

107. Indication 1. Prompt /immediate PRP Laser—(a) In ischemic CRVO with rubeosis iridis (NVI) and or NVA. (b) In ischemic CRVO with NVE and or NVD. 2. Prophylactic PRP Laser—In CRVO when close follow up is not possible. Macular grid laser has got no role even in CRVO with macular edema. Only PRP is done in CRVO when indicated. High-risk characteristics in CRVO • Visual Acuity <6/60 (or 20/200) • Angiographically extensive areas of capillary nonperfusion.

108. Technique Proper- PRP/Scatter Laser-In CRVO Parameters Exposure time— 100-500msec . Spot size— 500 - 1000 μm Intensity of burn-moderate, ½-1 burn spot size width apart No. of burns— 1200 - 2000 Location and pattern—Same as for scatter/PRP laser in diabetic retinopathy. * Presence of extensive areas of unresolved hemorrhage may prevent full laser application in all quadrants. *Photocoagulation should be avoided over areas of retinal hemorrhages, unless diode or krypton laser is used.

109. Follow up schedule Every month till regression of new vessels 1st follow up-1 month post laser • Undilated Slit-lamp examination and gonioscopy is a must to detect regression of new vessels (NVI and NVA). After regression of new vessels the follow up is carried out at 3 months interval.

110. Adequately lasered eye in a case of CRVO

111. PHOTOCOAGULATION IN RETINAL VASCULITIS Indications 1. Eales’ disease—Mainly indicated for ischemic and proliferative stages (Stage II and III). 2. Other causes of retinal vasculitis: • Pars planitis • Sarcoidosis • CMV retinitis • Behcet’s disease. Contraindication 1. Presence of active inflammation, i.e. phlebitis. 2. Stage I and IV of Eales’ disease.

112. Timing of Laser Photocoagulation is done in Eales’ disease/retinal vasculitis only after the inflammation subsides or is brought under control by oral steroid. In Eales’ disease/retinal vasculitis photocoagulation can be delivered through Slit-lamp biomicroscope/ Binocular indirect ophthalmoscope/Endolaser.

113. Photocoagulation Technique Proper Technique of “Anchoring photocoagulation “ is employed to eliminate or lessen complications. Photocoagulation of new vessels around posterior pole. Parameters Spot size—200-300 μm Intensity-Moderate to strong Placement-Focal burns around the neovascular tissue along temporal arcade are used. All neovascular extensions are similarly covered with focal photocoagulation burns. Additional sector PRP may be done prophylactically, if vitreous hemorrhage is anticipated.

114. CENTRAL SEROUS CHORIORETINOPATHY Formerly known as central serous retinopathy (CSR). Noninflammatory in nature,Characterized by serous macular detachment. Defect(s) in the RPE allows choroidal fluid to leak into the subretinal space. About 80% of eyes with CSCR undergo spontaneous resolution of subretinal fluid and a return to normal or near normal visual acuity within 1-6 months. Remaining 20% last longer but resolve within 12 months.

115. Indications 1. Persistent CSC of > 4-6 months duration. 2. Recurrent CSC with visual acuity < 6/12. 3. Chronic CSC. 4. Occupational need of the patient requires prompt recovery of vision. 5. Well-defined leaks > 500 μm away from the foveal center with a visual acuity of < 6/12.

116. Photocoagulation Technique Proper(focal laser) Parameters • Spot size-100-200 μm • Exposure duration-0.1 sec • Power—100-200 mW • Intensity—Grade 2 • Pattern—3-5 confluent burns. Follow up Schedule 1st – 2 weeks postlaser – OCT may be considered. 2nd– Every 2 weeks post 1st follow up.

117. Central serous detachment, early smokestack leak visible on FFA Focal laser of 2 pinpoint leaks > 500 μm away from the foveal center in CSC (Schematic drawing) 1 = FAZ (500 μm in diameter), 2 and 3 = Confluent 4- 5 laser spots

118. Subthreshold micro pulse laser In chronic CSCR 577nm, spot size 200-300 μm, 5% duty cycle upto 1000MW PLACE Trial- ICG guided high density 810nm ,5% duty cycle ,1800MW

119. RETINOPATHY OF PREMATURITY ROP is characterized by proliferation of abnormal vessels in premature infant’s peripheral retina. Blinding sequelae of ROP can be prevented only by timely intervention in infants at high-risk for progression. The intervention includes proper and complete ablation of the avascular retina by either cryoretinopexy or photocoagulation of all affected retinal quadrants.

120. Indications Threshold ROP (Stage 3, Zone 1 or 2, Extent 5 contiguous or 8 cumulative). Timing of Laser Within 24 to 48 hours of diagnosis. Photocoagulation Technique Proper Parameters • Spot size—100 μm • Exposure duration—0.3 sec • Power—300 mW • Intensity—Grade 2

121. Follow up Schedule 1st – 1week-post laser – Look for skipped areas – Look for signs of regression Flattening of mesenchymal ridge Disappearance of mesenchymal ridge 2nd – 2weeks-post laser – Look for signs of regression ( visible within 2 weeks post laser) – Retreatment may be considered in the absence of signs of regression – Treat skipped areas Every 2-4 weeks interval post regression of ROP.

122. PHOTODYNAMIC THERAPY

123. Contraindications to PDT

124. Mode of Action Verteporfin (Visudyne) is lipophilic (binds with LDL in the blood) and preferentially accumulates in the capillary endothelial cells of neovascular membrane. The accumulated dye absorbs specific wavelength (689 nm) of rays from laser emission. The light activated verteporfin converts normal oxygen to ‘singlet oxygen’. The highly energized ‘singlet oxygen’ and reactive free radicals destroy the endothelial cells of the CNV leading to occlusion of the neovascular membrane without collateral damage to the overlying photoreceptors.

125. DOSE

126. Schematic diagram showing injection of dye

127. Photodynamic Therapy Technique Proper Fifteen minutes after commencement of verteporfin infusion, i.e. 5 minutes after conclusion of dye infusion, the CNV is illuminated with light from diode laser (689 nm). Parameters Spot size-500 μm Size of the beam—The perfectly circular beam should cover the lesion entirely and is adjusted to extend 500 μm beyond the margin of the CNV membrane. So, size of the beam = 1000 μm + Greatest linear dimension of the lesion. Exposure time-83 seconds Intensity- 600 mW/cm² Total laser Energy-50J/cm² Dose of the Dye-6 mg/m² Unlike thermal laser (photocoagulation), visible retinal changes are not seen during laser application in PDT. In bilateral cases, the other eye may be treated immediately

128. TRANSPUPILLARY THERMOTHERAPY Transpupillary ThermoTherapy (TTT) is an alternative to Photodynamic Therapy (PDT) for treatment of subfoveal choroidal neovascular membrane (CNV) secondary to wet AMD. Mode of Action Intralesional marginal hyperthermia (max.10°C) occurs following exposure to large spot size, low irradiance over longer period of time from diode laser (810 nm-Infrared). This probably causes endothelial thrombosis and occlusion of the neovascular membrane, through release of free radicals, without collateral damage to the overlying photoreceptors.

129. Indications Occult subfoveal choroidal neovascular membrane (CNV) in Wet AMD Occult juxtafoveal choroidal neovascular membrane (CNV) in Wet AMD Retinoblastoma Choroidal hemangioma Choroidal melanoma. Contraindication Dry AMD Choroidal neovascular membrane (CNV) within 200 μm of the optic disc. Subfoveal choroidal neovascular membrane (CNV) with good visual acuity.

130. Timing of Laser TranspupillaryThermoTherapy (TTT) is done within 72 hours post recent FFA. Transpupillary Thermo Therapy (TTT) Technique Proper The CNV is illuminated with light from diode laser (810 nm). The perfectly circular beam should cover the lesion entirely. Parameters Spot size-0.8 mm/1.2 mm/2 mm/3 mm Exposure time-60 seconds (fixed) Power-200- 600 mW. It is titrated by placing a test burn in nasal retina. Absence of reaction or minimal reaction at the level of the RPE indicates optimum power requirement. The power also depends on the spot size. Smaller spot size requires less power. Indian eyes being more pigmented (contains more melanin pigments) require less power in comparison to European /Caucasian eyes.

131. TTT is delivered through a slit lamp using infrared diode laser at 810 nm Include a SLA, LIO and operating microscope adapter (OMA) indicated for all retinal photocoagulation including transpupillary thermotherapy (TTT) when used with an Oculight infrared system.

132. ENDOLASER PHOTOCOAGULATION Endophotocoagulation is used exclusively during a vitrectomy procedure. The endolaser photocoagulation is used primarily for treatment of bleeding from surface neovascularization, for retinopexy and for panretinal photocoagulation (PRP). Endophotocoagulation is used usually for surface bleeders from point sources.

133. Limitation: The only limitation of endophotocoagulation is that elevated areas cannot be treated. Advantage: Endophotocoagulation is a non-contact method and therefore dispersion of RPE cells, choroidal bleeding, retinal tears and subsequent increased size of the break associated with endocryopexy is avoided. Argon laser endophotocoagulation is preferable to xenon, because of greater probe-retina distance, better imaging in air, and more rapid firing.

134. The endophotocoagulation probe may have only a laser fiber, or may incorporate an aspirating port to help remove subretinal fluid. It may be angled or a straight probe. This probe is usually a 20-gauge instrument with an outer diameter of 0.89 mm. The usual spot size produced is approximately one mm. The power is set to minimum producing graying or just visible burn. Multiple solitary spots may be placed.

135. Other uses of LASER in Retina Barrage laser for peripheral retinal degenerations and tears PRP in peripheral chorioretinal tumours- Melanoma, Retinoblastoma, Angioma

136. Barrage Lasers for Peripheral retinal Degenerations

137. Lasers in Retinal breaks

138. Lasers in Peripheral Chorioretinal Tumours Angiomatosis Retinae Retinoblastoma Malignant Melanoma

139. Lasers for Angioma

140. Lasers in Retinoblastoma

141. Lasers in Malignant Melanoma

142. THANKS