In laser classifications, which class poses the highest risk for eye safety?

• A. Class 1
• B. Class 2
• C. Class 3B
• D. Class 4

Answer: (D)

Class 4 lasers pose the highest risk for eye safety due to their ability to cause immediate and serious damage to the eyes and skin upon exposure. These lasers emit high levels of power, which can result in the creation of hazardous conditions for both direct and scattered beams. Because they can produce a wide range of wavelengths and are capable of causing burns and fire hazards, strict safety precautions are necessary when working with Class 4 lasers.

In contrast, Class 1 lasers are considered safe under all conditions of normal use, and Class 2 lasers, while they can lead to minor injury with prolonged exposure, are mostly safe since the human reflex is often to flinch or avert one's gaze. Class 3B lasers can cause eye injury with direct exposure but are generally less hazardous than Class 4, as they do not typically generate the same degree of intensity and risk to both the skin and the eyes.