| Eye Laser |
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Laser is the acronym of Light Assisted /Amplification by Stimulated Emission Of
Radiation.
Physics
Certain substances have the property to lase; i.e. to absorb energy in one form, and to
emit a new form of light. On pumping, these lasing substance is able to transfer electrons
from a lower orbit to higher metastable orbit (Bohr;s theory).The excited atoms in turns
decay back to their original orbit of lower energy, thus emitting a new form of photons. |
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This decaying can be spontaneous, or induced ( stimulated emission).These photons
are passed through a close system of mirrors, which leads to light amplification, and
delivered as LASER. |
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Common Types Of Laser |
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1- Ruby Laser (first laser) wavelength 550nm
2- Argon Laser
Blue – green wavelength 488 nm
Pure Green Wavelength 518nm
3- Krypton Laser
Wavelength 647 nm
4- Nd- Yag Laser Neodymium ;Yttrium Aliminium Garnet
Single Frequency Wavelength 1064 nm
Double Frequency (pulsed) Wavelength 532 nm
5- Diode Laser
Wavelength 810 nm (Produced from semi conductor crystals.Lasing Substance ;Gallium Aluminium
Arsanate)
6- Excimer (Excited dimmer) laser( lasing substance ;Argon Fluoride )
Wavelength 193
nm. |
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Properties of Laser |
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1- It is always monochromatic (has got one wavelength of light)
2- It is collimated (all photons run parallel).
3- It is coherent (always in the same phase).
4- It is polarised at high energy level. |
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Laser effects on ocular tissues. |
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1- Photo coagulation (controlled burn)- Argon laser, Diode Laser, Krypton laser.
2- Photo vaporization –Argon Laser ,Diode Laser
3- Photo disruption ( optical breakdown to disrupt tissues by the formation of plasma)
Nd Yag Laser.
4- Photo Ablation (ablation of corneal tissue without thermal damage) Excimer laser |
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Indications of Laser |
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1-Iridotomy for Angle closure glaucoma.
2-Pupilloplasty.
3-Argon laser trabeculoplasty(ALT) in primary open angle glaucoma
4-YAG Capsulotomy for posterior capsular opacification.
5-To create chorio retinal adhesions around the retinal breaks.
6-Pan retinal photocoagulation (PRP)for proliferative retinal diseases and rubeosis iridis.
7-Central Serous Retinopathy (CSR).
8-Direct photo-coagulation to treat the vascular abnormalities.
9-“Macular grid” photocoagulation to treat macular lesions.
10-Intra ocular tumours and malignancy.
11-Photo refractive Keratoplasty(PRK) in refractive errors, lasik by Excimer laser.
12-Photo therapeutic keratoplasty (PTK) with Excimer Laser for superficial corneal
scars.
13-Trichiasis (cilia –ablation)
14-Suture removal (suturo- lysis)
15-Pterygium(to treat the bare area).
16-Cyclo Photocoagulation in glaucoma.
17-Diagnostic Laser Interferometry with Helium Neon Laser to test the potential visual
acuity in presence of opacity in the media. |
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Author: Dr. Sanjay Dhawan
Last Updated on: 1 March, 2014 |
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