All lasers in ophthalmology with principles and uses

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This is a large topic. Ophthalmic lasers can be organized as:

Core laser principles
- Laser properties: monochromaticity, coherence, collimation
- Tissue interactions: photocoagulation, photodisruption, photoablation, and selective photothermolysis
- Factors determining effect: wavelength, pulse duration, spot size, power, and tissue pigmentation
Photocoagulation lasers
- Argon, frequency-doubled Nd:YAG (532 nm), krypton, diode, and yellow lasers
- Retinal photocoagulation for diabetic retinopathy, retinal tears, retinal vein occlusion, and retinopathy of prematurity
- Transscleral and endoscopic cyclophotocoagulation for refractory glaucoma
Photodisruptive lasers
- Q-switched Nd:YAG laser
- Posterior capsulotomy for posterior capsule opacification
- Peripheral iridotomy for angle-closure mechanisms
- Membranectomy, synechiolysis, vitreolysis in selected cases
Photoablative lasers
- Excimer laser
- PRK, LASIK, LASEK, PTK, and selected corneal surface disorders
Femtosecond laser
- LASIK flap creation
- SMILE
- Femtosecond laser-assisted cataract surgery
- Corneal incisions, intrastromal rings, keratoplasty cuts
Other specialized lasers
- Selective laser trabeculoplasty (SLT)
- Micropulse diode laser
- Pattern-scanning retinal laser
- Laser peripheral iridoplasty
- Laser suture lysis after trabeculectomy

High-level principle: ophthalmic lasers deliver focused light of a chosen wavelength and pulse profile. Depending on how tissue absorbs that energy, the effect may be controlled thermal coagulation, plasma-mediated mechanical disruption, or precise tissue ablation.

Which section should I cover in detail first: principles, retinal lasers, glaucoma lasers, Nd:YAG procedures, refractive/corneal lasers, or an exam-oriented comparison table of all lasers?

Table

Reading File

This is a large topic. Ophthalmic lasers can be organized as:

Core laser principles
- Laser properties: monochromaticity, coherence, collimation
- Tissue interactions: photocoagulation, photodisruption, photoablation, and selective photothermolysis
- Factors determining effect: wavelength, pulse duration, spot size, power, and tissue pigmentation
Photocoagulation lasers
- Argon, frequency-doubled Nd:YAG (532 nm), krypton, diode, and yellow lasers
- Retinal photocoagulation for diabetic retinopathy, retinal tears, retinal vein occlusion, and retinopathy of prematurity
- Transscleral and endoscopic cyclophotocoagulation for refractory glaucoma
Photodisruptive lasers
- Q-switched Nd:YAG laser
- Posterior capsulotomy for posterior capsule opacification
- Peripheral iridotomy for angle-closure mechanisms
- Membranectomy, synechiolysis, vitreolysis in selected cases
Photoablative lasers
- Excimer laser
- PRK, LASIK, LASEK, PTK, and selected corneal surface disorders
Femtosecond laser
- LASIK flap creation
- SMILE
- Femtosecond laser-assisted cataract surgery
- Corneal incisions, intrastromal rings, keratoplasty cuts
Other specialized lasers
- Selective laser trabeculoplasty (SLT)
- Micropulse diode laser
- Pattern-scanning retinal laser
- Laser peripheral iridoplasty
- Laser suture lysis after trabeculectomy

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ophthalmic lasers principles uses Nd:YAG argon diode excimer femtosecond AAO

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Quick answer

Laser / wavelength	Main tissue effect and principle	Common ophthalmic uses	Key points
Argon laser 488 nm blue, 514 nm green	Photocoagulation. Absorbed by melanin and hemoglobin, producing thermal coagulation.	Retinal photocoagulation for proliferative diabetic retinopathy (PDR), macular edema, retinal tears, branch retinal vein occlusion; trabeculoplasty.	Green is preferred over blue because blue light is more absorbed by macular xanthophyll and can be more damaging. Largely replaced by 532 nm frequency-doubled Nd:YAG.
Frequency-doubled Nd:YAG (532 nm, green)	Photocoagulation	Panretinal photocoagulation (PRP), focal/grid laser, sealing retinal breaks, laser treatment in retinal vascular disease.	Widely used retinal laser. Strong absorption by hemoglobin and melanin.
Krypton laser 568 nm yellow, 647 nm red	Photocoagulation	Retinal photocoagulation, especially near the macula; selected choroidal lesions.	Red krypton penetrates through blood and xanthophyll relatively well, useful when media contain blood. Less commonly used now.
Yellow laser 561-577 nm	Photocoagulation	Macular edema, retinal vascular lesions, PRP, focal treatment.	Good hemoglobin absorption with relatively low xanthophyll absorption. Can be useful for macular work.
Diode laser 810 nm infrared	Photocoagulation	Retinal photocoagulation, retinopathy of prematurity, treatment through mild media opacity, transscleral cyclophotocoagulation (TSCPC), endoscopic cyclophotocoagulation.	Infrared penetrates sclera and pigmented tissues well. Important for refractory glaucoma through cyclodestruction.
Micropulse diode laser commonly 577, 810, or 532 nm	Repeated short “on” pulses separated by “off” periods, limiting thermal spread.	Subthreshold macular laser for diabetic macular edema/central serous chorioretinopathy; micropulse transscleral cyclophotocoagulation for glaucoma.	Aims to reduce collateral retinal pigment epithelium or ciliary-body damage compared with continuous-wave laser.
Pattern-scanning laser 532/577 nm	Photocoagulation, delivered as rapid pre-set arrays of spots.	PRP and macular retinal photocoagulation.	Faster delivery, shorter pulse duration, and more uniform pattern placement.
Nd:YAG laser 1064 nm, Q-switched	Photodisruption. Very short high-energy pulse creates plasma and shock waves, mechanically disrupting tissue.	Posterior capsulotomy for posterior capsule opacification; peripheral iridotomy for pupillary-block angle closure; membranectomy, selected synechiolysis, selected vitreolysis.	Main complications: transient IOP spike, inflammation, IOL pitting, retinal tear/detachment rarely after capsulotomy, and corneal endothelial injury.
Argon laser peripheral iridotomy	Photocoagulation causing thermal tissue destruction.	Alternative method for peripheral iridotomy in angle closure.	More difficult in thick/dark irides; often requires multiple burns. Nd:YAG is usually preferred.
Argon laser trabeculoplasty (ALT)	Photocoagulation of trabecular meshwork.	Primary open-angle glaucoma, pigmentary glaucoma, pseudoexfoliative glaucoma.	Produces structural thermal changes/scarring. Usually treats 180-360° of trabecular meshwork.
Selective laser trabeculoplasty (SLT) 532 nm, Q-switched	Selective photothermolysis of pigmented trabecular meshwork cells, with minimal coagulative damage.	First-line or adjunct treatment in open-angle glaucoma and ocular hypertension.	More repeatable than ALT. Lowers IOP by improving aqueous outflow. May cause temporary IOP rise or inflammation.
Laser peripheral iridoplasty (LPIp) usually argon or diode	Photocoagulation causes peripheral iris contraction.	Plateau iris configuration/syndrome; persistent appositional angle closure after patent iridotomy; selected acute angle-closure cases.	Not the same as laser peripheral iridotomy. Iridoplasty widens the angle by pulling peripheral iris away from trabecular meshwork.
Diode transscleral cyclophotocoagulation	Photocoagulation/cyclodestruction of ciliary processes, reducing aqueous production.	Refractory glaucoma, painful blind eye with high IOP, poor visual potential, selected difficult glaucomas.	Risks: inflammation, hypotony, phthisis bulbi, pain, vision loss. Micropulse variants aim to lower these risks.
Endoscopic cyclophotocoagulation (ECP)	Direct laser coagulation of ciliary processes, usually with diode laser.	Glaucoma, often combined with cataract surgery in selected eyes.	Direct visualization enables more targeted treatment than transscleral CPC.
Excimer laser 193 nm ultraviolet	Photoablation. Breaks molecular bonds with minimal thermal injury.	PRK, LASIK stromal ablation, LASEK, transepithelial PRK, phototherapeutic keratectomy (PTK) for superficial corneal scars, recurrent corneal erosion, band keratopathy, and selected dystrophies.	Removes corneal tissue with high precision. Does not cut a flap itself.
Femtosecond laser about 1053 nm infrared	Photodisruption with cavitation bubbles, allowing precise tissue separation.	LASIK flap formation; SMILE lenticule creation; femtosecond laser-assisted cataract surgery; arcuate keratotomy; corneal pocket/channel creation for rings; keratoplasty cuts.	Creates planes and incisions, unlike excimer laser, which ablates tissue.
Holmium:YAG laser 2100 nm	Thermal corneal tissue shrinkage.	Historically, laser thermal keratoplasty for hyperopia/presbyopia.	Largely obsolete because of regression and variable outcomes.
Er:YAG laser 2940 nm	Photoablation with high water absorption.	Limited/selected corneal surface applications.	Much less routine in ophthalmology than excimer laser.
Ruby laser 694 nm	Photocoagulation	Historically used in retinal photocoagulation.	Obsolete in routine ophthalmic practice.
Xenon arc photocoagulator not a laser	Intense thermal photocoagulation.	Historical retinal photocoagulation.	Replaced by lasers because it caused more pain and collateral tissue damage.

Rapid exam comparison

Laser category	Examples	Mechanism	Main uses
Photocoagulative	Argon, 532 nm green, krypton, yellow, diode	Heat-mediated protein coagulation	Retina, trabeculoplasty, cyclophotocoagulation, iridoplasty
Photodisruptive	Nd:YAG, femtosecond	Plasma formation and shock-wave tissue separation/disruption	YAG capsulotomy, YAG iridotomy, LASIK flap, SMILE, femtosecond cataract surgery
Photoablative	Excimer	Molecular bond breakdown	PRK, LASIK ablation, PTK
Selective photothermolysis	SLT	Selective absorption by pigmented trabecular cells	Open-angle glaucoma
Subthreshold/micropulse	Micropulse diode/yellow	Intermittent energy with less thermal spread	Macular disease and glaucoma cyclophotocoagulation

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