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Lasers in glaucoma - A Brief review
- 1. LASERS IN GLAU - COMA DR INDEEVAR V MISHRA GLAUCOMA AND ANTERIOR SEGMENT CONSULTANT M M JOSHI EYE HOSPITAL, HUBLI
- 2. PURPOSE… 1. DIAGNOSTIC 2. PROPHYLACTIC 3. THERAPEUTIC
- 3. DIAGNOSTIC 1. Optical coherence tomography (OCT) - Anterior segment imaging
- 5. 2. OPTICAL COHERENCE TOMOGRAPHY (OCT) - POSTERIOR SEGMENT IMAGING
- 8. MECHANISM PHOTOCOAGULATION - LASER LIGHT IS ABSORBED BY THE TARGET TISSUE OR BY NEIGHBORING TISSUE, GENERATING HEAT THAT DENATURES PROTEINS (I.E. COAGULATION) PHOTO DISRUPTION - POWER DENSITY IS SO GREAT THAT MOLECULES ARE BROKEN APART INTO THEIR COMPONENT IONS, CREATING A RAPIDLY EXPANDING ION ‘PLASMA.’ THIS IONIZATION AND EXPANDING PLASMA CREATE SUBSEQUENT SHOCK- WAVE EFFECTS WHICH CAUSE AN EXPLOSIVE DISRUPTION OF TISSUE TO CREATE AN EXCISION.
- 9. MECHANISM PHOTO ABLATION - BREAKS THE CHEMICAL BONDS THAT HOLD TISSUE TOGETHER, ESSENTIALLY VAPORIZING THE TISSUE
- 11. MODES OF OPERATION • CONTINUOUS WAVE (CW) LASER: IT DELIVERS THE ENERGY IN A CONTINUOUS STREAM OF PHOTONS. • PULSED LASERS: PRODUCE ENERGY PULSES OF A FEW MICRO TO MILLISECONDS. • Q SWITCHED LASERS: DELIVER ENERGY PULSES OF EXTREMELY SHORT DURATION (NANOSECOND). • MODE-LOCKED LASERS: EMITS A TRAIN OF SHORT DURATION PULSES (PICOSECONDS TO FEMTOSECONDS)
- 12. PROPHYLACTIC 1. LASER PERIPHERAL IRIDOTOMY (LPI OR PI) 2. ARGON LASER PERIPHERAL IRIDOPLASTY (ALPI)
- 13. LASER PERIPHERAL IRIDOTOMY (LPI OR PI) EAGLE TRIAL
- 14. PREPARATION •PUPILLARY CONSTRICTION •APRACLONIDINE / BRIMONIDINE •TOPICAL ANAESTHESIA •CORNEAL EDEMA MX
- 15. PROCEDURE •SELECTION OF SITE •LASER PARAMETERS – 4-6 MJ /1-3 PULSES PER BURST •POST PI MEDICATIONS
- 16. COMPLICATIONS •BLEEDING •CORNEAL BURN •IOP SPIKE INTRA OCULAR INFLAMMATION •RD, FOVEAL BURN
- 17. ARGON LASER PERIPHERAL IRIDOPLASTY (ALPI)
- 18. THERAPEUTIC – MINIMALLY INVASIVE PROCEDURES 1. ARGON LASER TRABECULOPLASTY (ALT) 2. SELECTIVE LASER TRABECULOPLASTY (SLT) 3. MICROPULSE DIODE LASER TRABECULOPLASTY (MDLT) 4. TITANIUM SAPPHIRE LASER TRABECULOPLASTY (TLT) 5. PATTERN SCAN LASER (PASCAL)TRABECULOPLASTY (PLT) LiGHT Trial
- 19. THERAPEUTIC – NON FILTERING GLAUCOMA SURGERIES OR/MAYBE/COULD BE “MIGS” 1. ND:YAG LASER GONIOPUNCTURE 2. EXCIMER LASER TRABECULOTOMY (ELT) 3. LASER ASSISTED DEEP SCLERECTOMY
- 20. CO2 – DEEP SCLERECTOMY
- 22. THERAPEUTIC - DESTRUCTIVE 1. TRANSSCLERAL CYCLOPHOTOCOAGULATION (TSCPC) 2. MICROPULSE DIODE LASER TRANSSCLERAL CYCLOPHOTO-COAGULATION (MICROPULSE TSCPC) 3. ENDOSCOPIC CYCLOPHOTOCOAGULATION (ECP)
- 23. THANK YOU!!!
Editor's Notes
- epending on the properties of the light source (superluminescent diodes, ultrashort pulsed lasers, and supercontinuum, optical coherence tomography has achieved sub-micrometer resolution.
- Anterior segment optical coherence tomography image of the right eye of a 50-year-old woman before (A) and after (B) cataract surgery. The angle-opening distance (AOD), The trabecular-iris space areas (TISA), The trabecular-iris angle (TIA).
- Accurate and reliable measurements of RNFL thickness and knowledge of the normal limits of RNFL is of clinical importance in early glaucoma diagnosis.
- The Heidelberg Retina Angiograph HRA (Heidelberg Engineering) uses an Argon- Blue-Laser (488nm) for excitation and a barrier filter for detection of emitted light above 500 nm. An increase of parapapillary autofluorescence in patients with ocular hypertension in comparison to the control group could indicate a cumulative deposition of lipofuscin material as potential precursor of increasing parapapillary atrophy and an early indicator for progression in this disease
- LPI has been widely used to treat angle-closure for over 20 years. This procedure is used to prevent or treat pupillary block in conditions such as angle closure glaucoma (AACG), primary angle closure suspect (PACS), pigmentary dispersion syndrome, phacomorphic glaucoma, aqueous misdirection, nanophthalmos, and plateau iris syndrome Nd:YAG laser is typically preferred because it is simpler to apply with fewer applications and may be more tolerable for patients. It also uses less energy and has lower closure rates On the other hand, argon LPI is less likely to cause hyphema since it is thermal and therefore coagulative and may be preferred in patients who are using anticoagulant medications or have visible iris vessels that are more prone to bleeding EAGLE Study Group compared lens extraction and LPI in newly diagnosed PAC or PACS
- Studies have found LI to be as effective or even more effective than conventional systemic and topical medications in reducing IOP levels in AACG and phacomorphic angle-closure, Residual appositional closure, caused by plateau iris syndrome, With a single laser application, 85-90% of angles remained open for up to 10 years of follow-up Complications of LI included mild iris inflammation, iridolenticular or angular synechiaes, iris atrophia, atonic pupils and rarely corneal endothelial burns
- ALT - IOP is typically lowered by 20-30% in 75-85% of patients treated by ALT. The efficacy of this procedure, however, diminishes over time by 50% over 5 years and 32% over 10 years. SLT - Given its efficacy, safety, repeatability and potential cost savings, it may be prudent to suggest SLT as an alternative to medications when discussing treatment options with a newly diagnosed glaucoma patient….its repeatable, safe and the initial 2 times is predictable….the third try usually fails to have much of an effect. MDLT – MDLT sub diode laser pulses - is suggested as a safe treatment modality with minimal anterior segment inflammation, however, further studies are needed to compare its efficacy with other laser treatment modalities, such as SLT. (TLT) - uses near infrared energy - TLT seems like another promising laser treatment modality, long term outcomes and possible complications should be further investigated. PLT - PLT results in less thermal damage than ALT, but does not effectively prevent late scarring of the trabecular meshwork. A pilot study found a 24% reduction in IOP, without IOP spikes or inflammation, over 6 months of follow-up. Long term results pending.
- Laser goniopuncture is an adjunctive procedure for non-filtering glaucoma surgery such as viscocanalostomy, deep sclerectomy and canaloplasty. The principle of ELT technology is to enhance the aqueous outflow by creating microperforations in the trabecular meshwork and the inner wall of the Schlemm’s channel , uses a xenon chloride excimer laser ab interno with a duration of 80 ns and a wavelenghth of 308-nm.
- Cyclophotocoagulation procedures have traditionally been reserved for glaucoma patients who are resistant to or not candidates for medical or surgical therapies, or are blind and suffer from eye pain due to end-stage diseases, especially neovascular glaucoma. Recently with the improvement in technology, these procedures no longer may reserved only for patients not candidates for medical or surgical therapy or having end-stage glaucoma. Reduce aqueous production by destruction of ciliary epithelium.