Which type of laser is most likely to cause retinal damage to the unprotected eye?

The near infrared diode laser is most likely to cause retinal damage to the unprotected eye due to its wavelength, which typically falls in the range of 800-1,100 nanometers. This range penetrates deeper into biological tissues, including the retina, with less scattering compared to other wavelengths. The human eye is particularly sensitive to light in this range, as the lens can focus infrared light onto the retina. As a result, exposure to this type of laser without proper eye protection can lead to significant retinal injury.

On the other hand, CO2 lasers emit light at a wavelength that is primarily absorbed by water, making them less likely to cause retinal damage since they do not penetrate as deeply into tissue. Similarly, traditional diode lasers and YAG lasers operate at wavelengths that are less hazardous to the retina when proper protection is in place. Understanding these differences in how various lasers interact with biological tissues is crucial for safety in laser therapy practice.