- Laser = Light Amplification by the Stimulated Emission of Radiation
- Laser emissions are:
- Collimated - parallel output beam results in little energy loss
- Coherent - waves are all in phase resulting in little loss of energy
- Monochromic - all of the same wave length
- Effects of laser depends on photochemical, photomechanical and photothermal effects
- Tissue penetration increases with wavelength
- Pulsing of output can reduce thermal damage
Uses of lasers
| Laser |
Wavelength (nm) |
Pulse length |
Uses |
| Carbon dioxide |
10,600 |
continuous |
tissue cutting |
| Neodymium-YAG |
1064 |
continuous |
coagulation |
| Neodymium-YAG
|
1064 |
10 ns |
posterior capsulotomy |
| Ruby |
694 |
100 mss |
tattoo removal |
| Argon |
488-514 |
continuous |
coagulation |
| Excimer |
308 |
10 ns |
photorefractive keratotomy |
Laser safety
- Lasers are classified according to the amount of damage they can cause
- Class 1 - generally safe
- Class 2 - safe within the time of the blink reflex
- Class 3 - cause blindness after short exposure from mirrored surfaces
- Class 4 - unsafe even with reflection from non-mirrored surfaces
- All medical lasers belong to class 4
- Both patients and operators require to wear goggles
Risks associated with lasers
- To patient
- Excessive burning
- Scar formation
- Visceral perforation
- To the operator
- Accidental skin exposure
- Corneal or retinal burns
Bibliography
McBurney E I. Side effects and complications of laser therapy. Dermatol Clin 2002;
20: 165-176 |