Which laser can cause corneal burns?

• A. Nd:YAG
• B. CO2
• C. Excimer
• D. Argon

Answer: (B)

When thinking about lasers and tissue, how the beam interacts with tissue depends on the wavelength. The cornea contains a lot of water, so lasers whose energy is strongly absorbed by water tend to heat and damage the surface. The CO2 laser emits energy at about 10.6 micrometers, a wavelength that is almost completely absorbed by water. That means the energy is deposited right at the surface of the cornea, rapidly heating and vaporizing tissue and producing a corneal burn if the beam is directed toward the eye or if protective measures are not used. Other common surgical lasers interact differently: some penetrate deeper before depositing energy, risking internal eye damage rather than surface burns, while others ablate tissue in a controlled way when used correctly. But the CO2 laser’s strong surface absorption by water makes corneal burns a notable risk, so it’s the most directly associated with causing corneal burns. Always use protective eye shielding and proper beam control to prevent ocular injury.