Laser in Ophthalmology

1. Lasers in Ophthalmology
Presented by : Dr. Aakanksha V. Bele
Moderator : Dr. Praveena Kher Ma’am
Jawahrlal Nehru Medical Collage, Sawangi (M), Wardha

2. Light Amplification by Stimulated Emission of Radiation
Term coined by Gordon Gould.
“LASE” – absorb energy in one form & emit a new form which is more useful.

3. History
1960
Invented by Theodore
Maiman in 1960 using a
Ruby crystal medium.
1963
1st clinical ophthalmic
use of laser in humans
was done in 1963.
1968
L Esperance developed
argon laser in 1968.
1971
Neodymium yttrium
garnet (Nd. YAG) &
Krypton laser were
developed in 1971.
1973
In 1973 Beckman & Sugar
became 1st to use Nd.YAG
laser for iridotomy &
trabeculoplasty.
1980
In 1980 Mizuno coupled a
binocular indirect
ophthalmoscope to an
Argon laser via a fiber
optic cable.
1983
The Photorefractive
keratoplasty by corneal
ablation was 1st
demonstrated by Trokel
in 1983 in bovine cornea
& in 1987 on human
cornea.
1996
IN 1996 LASIK eye surgery
became officially
approved by US
government.

4. Properties
• Directionality
• Monochromaticity
• Coherence
• Brightness

5. Fundamentals
of LASER
Radiation

6. Types of LASER used in Ophthalmology
1. Gas Lasers
1.1 Atomic lasers
1.2 Ion lasers of rare gases
1.3 Molecular lasers
1.4 Excimer lasers
1.5 Metal Vapor lasers
1.6 Chemical lasers
2. Liquid lasers (Dye lasers)
3. Solid state lasers
3.1 Laser doped insulator or solid-state laser (Crystal)
3.2 Laser made of semiconducting materials (Diode Laser)

7. Laser
Classification
based on
Wavelength

8. LASER – tissue
interaction
• It can be classified into:
1. Photochemical effects
2. Photothermal effects
3. Photoablative effects
4. Plasma induced ablation
5. Photo disruption effects
• Factors influencing photobiological effects are:
1. Optical characteristics of tissue - Reflection coefficient,
Absorption coefficient, Dispersion coefficient & Thermal
properties
2. Properties of Laser light – wavelength, exposure time,
applied energy, spot size & power.

9. LASER- tissue
interaction
1. Photothermal
Effects
Parameter – Wavelength, power density/irradiance,
exposure time, spot size, repetition rate.
Optical characteristics of biological tissues –
reflection/ refraction, absorption, scattering.
3 Stages of the process of tissue heating & thermal
effect:
• Optical stage
• Thermal or heat transport stage
• Thermal denaturation stage
Effects of biological tissue healing: Hyperthermia,
Coagulation, Vaporization & Carbonization

10. LASER tissue interaction
2. Photoablation
• Photoablation– direct breaking of molecular bonds by high
energy UV photons.
• Mainly applied for REFRACTIVE CORNEAL SURGERY such as
correcting myopia, astigmatism & hyperopia by corneal
modeling.
• 1st described by Srinivasan in 1982.
• 2 Staged process : Excitation & Dissociation
• Only UV light photons (typically excimer lasers) have
sufficient energy to dissociate the molecular bonds.
• Absorption of UV energy in cornea occurs for wavelengths
lower than 300nm; it is primarily collagen that are
responsible for ablation & its effect.
• The major concern with this radiation is its potential
mutagenic & carcinogenic effects.

11. LASER – tissue
interaction
3. Photodynamic
Therapy
• The 3 components needed for PDT are :
1. Chromophore- photosensitizer – which
after administration is captured
selectively by target cells.
2. Light with a selected wavelength &
appropriate energy to induce desired
photochemical effect.
3. oxygen
• PDT effects occurs as:
1. Direct & immediate cytotoxic effect
2. Vascular effects – vasoconstriction
3. Hyperthermia
• Clinical application – intraocular tumor,
ocular neovascularization, age- related
macular degeneration, polypoidal choroidal
vasculopathy & chronic central serous
chorioretinopathy.

12. LASER – tissue
interaction
4. Plasma
generation &
Plasma induced
ablation
• Optical breakdown is the first step for plasma mediated
ablation, enabling:
1. Precise tissue removal
2. Absence of thermal effects
3. Absence of mechanical effect
• Plasma Generations :
- Q-switched pulses, in the nanosecond range, or mode
locked laser pulses, in the pico or femtosecond range,
can generate ionization & subsequent electron
avalanche of plasma induced ablation.
• The duration of laser pulse is fundamental in defining
the 2 possible process of plasma generation:
1. Thermionic emission
2. Multiphoton ionization

13. • Q – switched pulses originate thermionic emission;
hence ionization triggers the generation of free
electrons & optical breakdowns thus generated by
nanosecond duration laser pulses & is often
accompanied by non – ionizing side effects such as
heat.
• Mode locked pulses originate multiphoton ionization:
in pico or femtoseconds, several photons are
simultaneously absorbed originating the energy
needed for ionization required to create an induced
high electric field.
• Plasma generation can therefore be summarized in 3
steps:
1. Absorption of a photon by an atom resulting in its
ionization – duet positive ion – free electron
2. Free electrons absorb photons of beam, gaining
velocity
3. There accelerated electrons collide with another
atom, causing ejection of more electrons, in a
continuous process

15. Optical breakdown & plasma generation enables:
• Energy delivery to both pigmented & non-pigmented tissues
• Absorption of any amount of energy to increase the kinetic
energy of electron
• Swift & intense ionization, thus avoiding energy dissipation
before the electron avalanche, which is created by an ultrashort
& intense irradiation leading to optical breakdown.
Application : potential medical laser applications are
thus widened to transparent tissues like cornea & lens.
Relevant aspects of this laser-tissue interaction effect:
• Optical tissue breakdown
• Ultrafast duration & high energy density of pulse laser
• Minimal or no collateral damage in surrounding tissue
• Wider application to non- pigmented tissues
• Accuracy & precision of application

16. LASER – tissue interaction
5. Photodisruption

17. Mechanisms of
LASER delivery

18. Contact lenses
for LASER
treatment
• Contact lenses for anterior segment surgery
- LASER surgery for glaucoma & iris –
Abraham iridectomy lens, Goldmann 3
mirror lens, single mirror gonio laser lens &
Ritch trabeculoplasty lens
- LASER surgery for pupillary area & suture
lysis - Abraham capsulotomy YAG laser lens,
Peyman G. capsulotomy lens & Hoskins
nylon suture laser lens
• Contact lenses for posterior segment laser
surgery :
- Plano concave or negative lenses, Glodmann
fundus lens & 3 mirror lens, Krieger/ yanuzzi
lens, Convex, positive or high plus lenses,
Rodenstock panfundoscopic lens, Mainster
lens, Volk trans equator lens & Volk
quadraspheric lens

21. Laser
Safety
Checklist
Appropriate warning signs posted
Access to laser & treatment area is secure & controlled
Visually inspect & clean all optical connectors for dirt, debris, etc
Inspect laser for proper function
Inspect & clean all safety goggles
Extra goggles placed outside treatment room
Treatment protocol established for patient
Laser injury management protocol in place for accidental injury

23. LASER
surgery in
Cornea
Excimer Laser
Femtosecond LASER in
corneal surgery
Corneal
neovascularization

24. Excimer LASER or excited dimer
• Once laser encounters body tissue 4 distinct processes may take action : absorption,
transmission, reflection & dispersion.
• Absorption & transmission have the biggest impact on human cornea.
• 3 process may occur after photoabsorption : photothermal, photodisruptive & photochemical
effect.
• Photochemical events can be divided into photoradiation & photoablation.
• For refractive surgeries PHOTOABLATION is of interest.
• Delivery : scanning slit delivery, full beam delivery, flying spot delivery
• Indications : age >18yrs & stable refractive error in last 1 yr.

25. • LASIK ( LASER assisted in situ keratomileusis) :
- Mild to moderate myopia <-8D sphere (<-14D); mild to moderate
hypermetropia <+4D sphere (<+6D) & mild to moderate astigmatism <5D
cylinder (<6D).
- Corneal pachymetry >500 µm, residual stromal thickness of 250 µm (
Percentage of tissue altered under 40%) & post op keratometry of 35/36 –
48/50 D are needed
• PRK (photorefractive keratectomy) :
- Mild to mod. Myopia <-6D sphere (<-12D); low hypermetropia <4D sphere;
low to mod. Astigmatism <4D cylinder.
- Situation where creation of corneal flap is not ideal.
• LASEK (LASER assisted sub- epithelial keratectomy) :
- Corneal pachymetry of less than 500 µm
- Deep set eyes or narrow palpebral fissure
- Post- LASIK correction of flap
- Previous intolerance to LASIK in fellow eye
- Case of recurrent epithelial erosion.

27. • Post LASER care & follow up:
- Topical antibiotic 4 times a day for 1 week 💧
- Topical corticosteroids 4 times a day for 1 week; then taper.
- Preservative free hyaluronic acid for 1- 4 months
- Topical NSAIDS in case of pain 😢
- Remove BCL after 3– 5 days.
- Topical mitomycin C as prophylactic to avoid corneal haze
- IOP monitoring
• Complications:
- LASIK – flap defects, incomplete or dislodged flaps with folds, epithelial defects & corneal perforation, refractive
complication, dry eye, etc
- PRK – insufficient epithelial removal, infection, monocular diplopia, ghost images, decreased contrast sensitivity,
halos & glare
- LASEK – free epithelial flaps, dissolution, fragments, folds & slips
• Result: LASIK permits treatment of high myopia, rapid & pain free recovery; PRK has lower incidence of corneal
ectasia but has difficult post op period; LASEK comparatively has lower complications
• Retreatment is required in 0- 6.7% along 4yrs.
• Patient satisfaction is seen in over 95%. 😃

28. Femtosecond
LASER in
corneal
surgery
• Unlike excimer laser which works on the principle of
photoablation, femtosecond laser works on the principle
of photodisruption.
• The Intralase femtosecond mode laser was designed to
address most limitations of current systems. This laser
system uses 1053nm (infrared) wavelength.
• Femtolaser is being used in following corneal surgeries:
- Lamellar keratoplasty
- Penetrating keratoplasty
- Intralase- enabled keratoplasty for laser designed shaped
incisions (mushroom incision, top hat, zig zag)
- Intracorneal ring segments
- Corneal biopsy
• Disadvantages : suction break, cost

29. Corneal Neovascularization
• Corneal neovascularization defines ingrowth of blood vessels into
the corneal tissue, which is normally devoid of vascular &
lymphatic structures.
• Indication : to treat corneal NV prior to keratoplasty in order to
reduces chances of graft rejection.
• Contraindication : no specific contraindication
• Laser used : Argon 514.5nm (green – blue), Nd: YAG KTP 532nm
(yellow – green), Yellow Diode 577 nm (yellow)
• Complication : temporary intrastromal hemorrhages, corneal
lesions, corneal thinning, descemetocele, iris damage, iris atrophy
& accidental lysis of keratoplasty sutures.
• Result : The main downside of this treatment is the frequency od
adverse reaction.
- Afferent vessel obliteration is less successful because of deeper &
narrower dimensions & rapid pulsatile flow.
- Other concerns include: cataract & damage to retina.

30. LASER
surgery in
Glaucoma
LASER iridotomy
Peripheral iridoplasty/ gonioplasty
Trabeculoplasty
LASER suture lysis
Anterior hyaloidotomy & transcleral
cyclophotocoagulation
Cyclophotocoagulation

31. Laser Iridotomy
• Indication : to prevent a suspected relative pupillary
block by creating a bypass for aqueous flow.
• Primary angle closure glaucoma, primary angle closure
suspects & acute angle closure
• Laser Technique : Nd:YAG Iridotomy at 11 or 1’o clock
position
• Abraham iridotomy lens is used.
• Reassess in 1-2 hrs (IOP spike)
• Complication : Iris hemorrhage, transient IOP elevation,
inflammation, corneal injury, accelerated cataract
formation, failure to perforate, ghost images, glare,
halos, cystoid macular oedema, etc
•

32. Peripheral iridoplasty/
gonioplasty
• Indication : failure of laser iridotomy
• Contraindication : corneal edema or
opacification, very shallow anterior
chamber, peripheral anterior synechiae
• Laser technique : Nd:YAG-KTP Laser (blue-
green) 488-515nm, spot size – 300-500 µm,
for 0.5- 0.7sec, power – 200- 500mW
• Post laser care : topical steroids 3-4 times a
day for 1 wk. Monitoring of IOP
• Complications : mild iritis, iris pigment
hypertrophy, increase IOP, Diffuse corneal
endothelial burn.

33. Trabeculoplasty
• Indication : uncontrolled open angle glaucoma, OAG with poor compliance or not willing to use medical
therapy
• Contraindication : angle closure glaucoma, glaucoma associated with uveitis, juvenile glaucoma
• Laser technique :
- ALT : Argon or Nd:YAG-KTP 532nm continuous wave (green) or Diaode 577nm (yellow); spot size – 50µm for
0.1 s; 50-100 spots separated by 3-4 burns with over 180- 3600.
- SLT : Nd:YAG-KTP 532nm Q-switched pulsed laser, spot size - 400µm for 3ns; 50-100 non- overlapping sots
over 180- 3600.
• Post Laser care :apply 1% apraclonidine immediately following the procedure. Reassess IOP after 1 hr.
Topical corticosteroids 4 times a day for 1 wk
• Follow up : weekly for 6 wks
• Complications : transient IOP elevation, mild inflammation, hyphema, peripheral anterior synechiae

34. LASER
surgery in
Iris/ Pupil
Pupilloplasty, photomydriasis
& synechiolysis
Persistent fetal vasculature
Corticolysis &
membranectomy

35. Pupilloplasty, Photomydriasis
& Synechiolysis
• Indication : miotic pupil, pupillary block glaucoma, synechia to lens
or its capsule or anterior hyaloid.
• Contraindications : active uveitis, cloudy cornea
• Laser technique : Nd:YAG-KTP 532nm in 2 stage.
- Stage 1 (inner margin): 3600 contiguous, concentric laser burns
adjacent to pupillary margin. Spot size – 200µm for 0.2s at power of
200-400mW
- Stage 2 (out margin): Spot size - 500µm for 0.4s at power of 400-
500mW
• Post laser care : Topical steroids, topical tropicamide for 1 wk
• Follow up : weekly
• Complications : Ocular hypertension, hyphema, pigment dispersion,
transient iritis, cataract, glare

36. Persistent
Fetal
Vasculature

38. LASER
surgery in
lens
Nd:YAG – Q-switch LASER anterior
capsuloplasty
Posterior capsulotomy
Pigment Nd:YAG ”Q-switch” LASER sweeping
Repositioning of posterior chamber IOL
Femtosecond LASER – assisted cataract
surgery

39. Anterior Capsuloplasty

40. Posterior Capsulotomy

41. Femtosecond LASER – assisted
cataract surgery (FLACS)
• Femtosecond laser use ultrashort-pulses near infrared wavelengths
to induce formation of plasma, allowing one to cut through tissue
while causing minimal damage to surrounding structures.
• With FLACS number, size, position, depth & tunnel morphology of
clear corneal incisions can be adjusted.
• Capsulorhexis by FS are more accurate & has more strength
compared to manual capsulorhexis.
• FS laser devices can lay out a pattern of cuts into the lens nucleus
that can effectively divide nucleus into small fragments, thus
allowing it to be more easily aspirated.
• Limitation : expensive, capsular block syndrome, dropped nucleus,
incomplete capsulorhexis, intra-op miosis & endothelial damage.

42. LASER
action in
Retina
LASER in diabetic retinopathy
Photocoagulation therapy for vascular vein occlusion
Phototherapy for AMD
Non damaging retina laser in central serous chorioretinopathy
Subthreshold micropulse laser in central serous
chorioretinopathy
Idiopathic macular telangiectasia
Coat’s disease
Retinal microaneurysm
Ocular ischemic syndrome
Eales’ disease
Idiopathic choroidal neovascularization

43. LASER treatment for Proliferative Diabetic
Retinopathy - PRP
• Treatment goal : new vessel regression or inactivation.
• PRP in PDR with coexisting DME can be vision threatening, hence
focal or grid laser photocoagulation should be carried out prior to
PRP.
• Side effects : pain, impairment of color vision & contrast sensitivity;
peripheral visual field constriction, exacerbation of DME.

44. Photocoagulation therapy for vascular vein occlusion
(BRVO or CRVO)
Macular Grid Laser
• Indication : macular edema secondary to BRVO
• Laser technique :
- Conventional laser : 100µm size, 0.05-0.1s at low power of 60mW. Apply burns one width apart
- Micropulse laser
- Sector scatter photocoagulation
- Complications : premacular fibrogliosis, visual field defects, pigmented epithelium atrophy
Panretinal photocoagulation
• Indication : ischemic complications – rubeosis & retinal neovascularization
• Laser technique : 500µm size, 0.1-0.2 s & power should be sufficient to give medium white burns. 1 burn apart & total
1200-2500 spots.
• Complications : choroidal hemorrhage, premacular membrane, accidental burn of fovea, macular edema, visual field
defects & night vision problems.

45. Laser therapy in Central Serous Chorioretinopathy
• Indication : chronic or recurrent CSC
• Contraindication : Subthreshold laser should not be applied over areas of hemorrhages or intense
pigmentation that could cause photocoagulation of photoreceptors
• Laser technique : Micropulse laser technique (LASER 577 nm yellow) &PASCAL endpoint management
laser technique (532 nm green or 577 nm yellow)
• Follow up : 3 monthly
• Usually no complications are seen
Titration Micropulse
Spot size 200µm 200µm
Duration 200 ms 200 ms
Spacing Single spot High density
Energy 100% Micropulse mode

46. Ocular Ischemic
Syndrome
• Laser technique : Nd:YAG-KTP 532nm (green)
- Start with 400-500 µm spot size on retina, 0.1 s exposure
time & 350-400mW power.
- More than 700-800 spots are avoided in single session
• Complications : pain, impairment of color vision &
contrast sensitivity; peripheral visual field constriction

47. Endolaser
&
Vitrectomy
LASER delivery in operating room
Laser in RD
Peripheral RD & tears
Retinal lesions with difficult access

48. Laser in retinal
detachment
• Laser for RD without vitrectomy, or
demarcation laser photocoagulation refers to
placement of confluent laser photocoagulation
burns along margins of RD.
• Indications : Shallow RD or asymptomatic
patients
• Contraindication for DLP : PVR, large or
bullous RD, Macular or near foveal
detachment, detachment near optic disc

49. Peripheral Retinal detachment & tears
Prophylactic Treatment : Laser retinopexy is primary treatment for retinal breaks. The goal is to
create a firm chorioretinal adhesion around the tear in the attached adjacent retina, thus
preventing progression to RRD.
Laser Technique : power – 300-500 mW, duration – 0.1-0.2sec, spot size – 300-500 µm in retina.
3- 4 rows of creamy white contiguous laser burns are placed.
Complications : choroidal effusion, angle closure glaucoma, epiretinal membrane formation,
anterior segment laser burns, hemorrhage in retina, vitreous or choroid, formation of new
breaks
Follow up : after 1-2 wks

50. Retinal Lesions with difficult
access
• Indications : small pupil, focal opacities, gas bubbles in eye, peripheral retinal pathology (retinal breaks, lattice
degeneration or peripheral neovascularization) or in patients who cant sit on slit lamp
1. The indirect ophthalmoscope consists of a standard argon/ Nd:YAG KTP 532nm laser console joined to the
ophthalmoscope via a quartz fiber.
Contraindications : macular photocoagulation
Laser technique : Nd:YAG KTP 532nm laser/ Argon 514.5 nm laser for 0.05s- 2s at power of 200mW-400mW at
continuous pulse.
Tips :
- same laser energy given over a longer pulse duration is less likely to cause choroidal hemorrhage than repeated
shorter pulses
- Cornea must be kept moist
- With air filled phakic eye 20 D lens should be moved away from the patients eye to obtain a reasonably small spot
size
Complications : Choroidal hemorrhage & macular or foveal burns

51. 2. Transscleral diode laser photocoagulation
have replaced cryotherapy in treatment of very
peripheral retinal lesion or in eyes with media
opacities
Contraindication : Macular or very posterior
lesions
Laser technique : Diode laser 810nm infrared
laser beam for 100ms-3s at power of 100-
1000mW
Complications :scleral thermal effects, apparent
ruptures of Bruch’s membrane & intra ocular
hemorrhage.

52. LASER in
Pediatric &
Hereditary
conditions
Retinopathy of
prematurity
Familial exudative
viteroretinopathy

53. Retinopathy of Prematurity
• ROP is a vasoproliferative disease, secondary to an inadequate vascularization of immature retina in pre-term
infants.
• In 1980s, transscleral cryotherapy became the first effective treatment for avascular retinal ablation in ROP.
• In 1990s, development of laser system coupled with an indirect ophthalmoscope allowed retinal laser ablation
by photocoagulation of avascular retina.
• Indication : ETROP study recommends early treatment in high risk or type I pre-threshold ROP within 48hrs.
• Laser used : Diode laser 810nm & Nd:YAG KTP 532nm. Diode laser 819nm has advantage as it has less risk of
cataract formation, synechiae & vitreous contraction.
• Post laser care & follow up : Topical antibiotic, corticosteroid & cycloplegic. Evaluate one day after treatment,
then after 1 wk & then fortnightly depending on response to treatment.
• Complications :
- Ocular – pain, cornea iris or lens burns, hyphema, myopia,
inflammation, epiretinal membrane
- Systemic – Apnea, bradycardia & need for intubation.

54. Familial exudative
Vitreoretinopathy
• FEVR is a disease with ocular findings similar to those
of ROP but occurring in full – term newborns.
• It is a rare inherited disorder of retinal angiogenesis,
seen in full term babies.
• Therapeutic options : laser photocoagulation,
cryotherapy & vitreoretinal surgery.
• Indication : Neovascularization & retinal exudation
• The treatment, complication, post laser care & follow
up are similar to that of ROP.

55. LASER in
Retina/
Choroid :
Tumors
Malignant melanoma
Retinoblastoma
Retinal capillary hemangioma
Pigmented lesions of retina &
choroid accessible to OCT

56. Malignant melanoma
Transpupillary thermotherapy is mainstay for small tumors
Indications : small tumors (as primary treatment); 12mm or less basal diameter, 4 mm or less thickness, located
posterior to the equator of eye.
Contraindication : pupil is not dilated, tumor in far periphery, anterior or posterior segment opacities,
overhanging optic disc.
Laser technique : Near infrared diode 810nm; spot size of 2-3mm for 60 secs, with power of 300-600 mW. The
goal is to have grayish discoloration of tumor.
Follow up : 2 months
Complications : retinal & choroidal vascular occlusion, retinal hemorrhage, tractional RD, epiretinal membrane,
cystoid macular edema, retinal neovascularization, retinal breaks, iris atrophy & post laser pain.

57. Retinoblastoma
• Indication :
1. primary treatment of small tumors up to 3mm thickness & 3-4.5 mm in diameter
2. adjunctive treatment after systemic or intra—arterial chemotherapy.
• Relative contraindication :
- Tumor >4.5 mm in diameter or >2.5mm in thickness
- vitreous seeding;
- tumor located anterior to equator
- tumor touching optic disc.
• Laser technique :
1. ND:YAG KTP 532nm laser given continuously at power of 80-100mW
2. Diode Laser 810 nm given for 0.5-9secs at power of 500-700mW
• Follow up : Several treatment sessions may be required
• Complications : Tumor seeding into vitreous, retinal fibrosis & traction, retinal vascular occlusions, vitreous hemorrhage, retinal hole,
transient retinal detachment, iris atrophy & focal cataract

58. LASER in
vitreous
Anterior segment
vitreolysis
Posterior
vitreolysis

59. Anterior segment vitreolysis
• Indication : vitreous strands in the anterior chamber adherent to corneal wounds causing
pupillary distortion or originating posterior vitreous traction with cystoid macular edema.
• Contraindication : untreated retinal tear, active intraocular inflammation or uncontrolled
ocular hypertension.
• Laser technique:
- Nd:YAG 1064nm Q-switch laser given as single pulse, spot size 8 µm for 4 ns with power of
1.4 to 2.5mJ.
• Post laser care & follow up : topical steroids with NSAIDs; follow up after 5 days of
treatment & thereafter as needed.
• Complication : corneal edema & leukoma, ocular hypertension, hyphema, iris atrophy,
increased anterior chamber inflammation & macular edema.

60. Posterior Vitreolysis
• Indication :
1. Removal of symptomatic vitreous opacities in the optic axis or preventing a proper fundus
examination
2. Removal of vitreous traction over retina
3. Facilitation of vitreous hemorrhage clearing
• Contraindication : active inflammatory vitreous or retinal pathology, vitreoretinal traction, high
lenticular astigmatism, RD, young patients with multiple small opacities close to retina, active
retinal neovascularization.
• Laser technique : Nd:YAG 1064nm Q-switch laser (QS-YAG)
• Post laser care & follow up : Topical steroids. Follow up weekly
• Complications : cataract, retinal pigment epithelium, retinal hemorrhage, retinal scarring.

61. LASER in
Oculoplastic
surgery
CO2 laser: blepharoplasty & resurfacing
Trichiasis
Periocular benign skin lesions
Ablative LASER treatment for pigmented lesion
Periocular lesions associated to HPV
Periocular vascular skin lesion
Conjunctival lesions
TCLA DCR (Transcanalicular diode LASER – assisted
dacryocystorhinostomy)

62. CO2 Laser
blepharoplasty &
resurfacing
• Skin resurfacing with the CO2 10600nm laser system remains the
gold standard technology for the most photodamaged & scarred
facial skin.
• Using CO2 laser for skin resurfacing yields an additional benefit of
collagen tightening through the heating of dermal collagen.
• Operative technique for ablative resurfacing laser selection :
- erbium-YAG laser emits 29400nm & CO2 emits 10600nm.
- 80µm of tissue will be ablated per pass.
• Complications : bacterial cellulitis, pruritis, milia, post-
inflammatory hyper or hypo-pigmentation, scarring & persistent
reythema
• Avoid topical antibiotics.
No. of pass
Forehead 2-3
Intraorbital eyelids 1
Cheeks 2-3
Perioral lips 2-3
Angle of mandible 2
Upper neck 1

63. Trichiasis
• Indication : for upto 6 eyelashes
• Laser technique : Nd:YAG-KTP 532nm laser or Yellow
diode 577nm laser.
- Done in 2 stages : stage 1 – the first burns & stage 2 –
coagulation of the bed of follicle.
• Complication : recurrence, mild hypopigmentation,
notching, lid margin retraction & mild contour
abnormalities.

64. Periocular
benign
skin
lesions

65. Conjunctival
lesions
• Indication : conjunctival nevus & warts
• Laser technique :
- Conjunctival nevus : 532nm (green) QS-
KTP laser, spot size – 200µm, duration –
0.1s; power- 300-340mW
- Conjunctival warts : CO2 laser in
continuous mode, starting power at 6.0W
• Post laser care : Topical corticosteroids
Patient with conjunctival
wart
1st day after CO2 LASER treatment
1 wk after treatment
Presence of
conjunctival burns
2 wks after treatment
Non- visible papillomatous lesion,
along with partial conjunctival healing

66. Transcanalicular diode
laser-assisted
dacrocystorhinostomy
(TCLA DCR)
• Indication : epiphora
• Contraindication : acute or chronic dacryocystitis,
sac mucocele, bone fracture, dacryolithiasis,
lacrimal fistula, lacrimal sac or nose tumors,
extensive polyposis, allergic rhinitis
• Laser technique : laser diode with wavelength of
810-980 nm given by optical fiber.
• Complications : canalicular stenosis, necrosis of
medial canthus, temporary changes of olfaction

67. Diagnostic
LASER
• OCT (optical coherence
tomography)
• SS – OCT (LASER swept source
OCT)
• cSLO (confocal scanning LASER
ophthalmoscope)
• OCT Angiography
• Wavefront aberrometry

68. LASER
Simplified
Laser interaction Mechanism of
action
Clinical effect Example
Photothermal
(Photocoagulation &
Photoevaporation)
Coagulation of
proteins
Tissue burns Argon
Nd: YAG
Photoablation Breakage of
interatomic bonds
Tissue etching Excimer
Photo radiation Generation of
cytotoxic free
radicals
Oxidative tissue
damage
Photodynamic
therapy
Photo disruption Stripping of
electrons from
atoms, the
formation of
plasma/ shock wave
Cuts tissue Nd: YAG (Q
switched)

69. LASERS
Simplified
• ND YAG NICKS & ARGON is an ADHESIVE
(Nd YAG laser cuts & argon laser seals)
• Uses of Nd YAG – cutting/ tomy
- After cataract
- Iridotomy
- Vitreolysis
• Uses of ARGON – coagulation/ plasty
- PRP
- Trabeculoplasty
- Iridoplasty
wavelength of Nd YAG is 1064 nm and that of ARGON LASER
is 514 nm so if we double the frequency of Nd YAG laser then
its Wavelength will become half which is in range of argon
laser so DOUBLE FREQUENCY Nd YAG has same use as argon
laser

70. LASERs
Simplified
• DIODE & KRYPTON LASER has same function as of argon
laser in retinal photocoagulation
• EXCIMER OR ARGON FLUORIDE LASER ( 193 nm): it is used
in LASIK , LASEK , PRK ie refractive surgery

71. Lets solve
MCQs

72. In the LASER machines used in ophthalmology, the
atomic environment used consists of:
a. Crystal rod
b. Fluid – filled cavity
c. Gas – filled cavity
d. Any of the above

73. Photo disruption is the basic mechanism of
action of:
a. Argon laser
b. ND: YAG laser
c. Excimer laser
d. All of the above

74. All the following are indications for pan retinal
photocoagulation except:
a. Pre- proliferative diabetic retinopathy
b. PDR
c. Ischemic CRVO
d. CRAO

75. LASER photocoagulation is useful in all of the
following macular disorders except:
a. Exudative age – related macular degeneration
b. Central serous retinopathy
c. Focal type of diabetic maculopathy
d. Aphakic cystoid macular edema

76. YAG Laser is used in the treatment of
a. Retinal Detachment
b. Diabetic Retinopathy
c. Open angle glaucoma
d. After cataract

77. The laser procedure, most often used for
treating iris neovascularization, is:
a. Goniophotocoagulation
b. Laser trabeculoplasty
c. Panretinal photocoagulation
d. Laser iridoplasty

78. A premature baby on examination shows bilateral ROP
(Zone1, Stage 2 with plus disease). How will you manage
the patient?
a. Follow up after 1 week
b. Laser photocoagulation of both eyes
c. Laser photocoagulation of worse eye
d. Vitreoretinal surgery

79. Photo disruption is the basic mechanism of
action of:
a. Argon laser
b. ND: YAG laser
c. Excimer laser
d. All of the above

80. References
Laser manual in ophthalmology by Jose Henriques. 1st edition
www.Eophtha.com
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799025/laser
safety guidelines