A patient presents to you for a laser consultation for spots on face. You discuss the risk of ocular damage with the use of lasers and the importance of proper eye protection. Which of the following lasers is most associated with corneal/scleral damage?
A. KTP (532nm)
B. PDL (595nm)
C. Alexandrite (755nm)
D. Nd:YAG (1064nm)
E. CO2 (10,600nm)
Rationale: LASER stands for light implication by stimulated emission of radiation. Lasers are monochromatic, coherent, and collimated and the various media can determine the wavelength of light produced. The choice of which type of laser to use depends on the target chromophore.
Correct answer: E. CO2 (10,600nm)
Lasers that target water such as Nd:YAG (1320nm), Erbium:glass (1500nm), Erbium:YAG (2940nm), and CO2 (10,600nm) can cause corneal or scleral damage due to water content.
Incorrect answers: A-D
Lasers that target melanin or hemoglobin such as the KTP (532nm), PDL (585-600nm), Ruby (694nm), intense pulsed light, Alexandrite (755nm), Diode (800nm), and Nd:YAG (532 and 1064nm) can cause retinal damage, due to the heavily pigmented retina, as well as damage the uvea and iris.
Additional reading at Fitzpatrick's Dermatology Chapter 208: Fundamentals of Laser and Light-Based Treatments