How does continuous wave (CW) lasers primarily cause eye damage?

Continuous wave (CW) lasers primarily cause eye damage through tissue heating. When the focused beam of a CW laser enters the eye, it can lead to thermal effects due to the absorption of the laser energy by ocular tissues. The tissues, particularly in the retina, can become heated to the point of damage, resulting in a thermal injury that can lead to permanent vision loss.

This mechanism of damage is particularly dangerous because it does not necessarily require immediate and intense exposure; prolonged exposure, even at lower intensities, can accumulate thermal energy, leading to significant tissue injury over time. The heating effect can disrupt cellular structures and cause a range of visual impairment, including potential scarring or complete retinal detachment.

Other options like creating instant retinal burns are associated more with high-intensity pulsed lasers rather than with continuous wave lasers, which operate over an extended period. Light flicker may cause discomfort or temporary visual disturbances, but it does not lead to the same direct tissue damage seen with heating. Prolonged photophobia, while a concern for eye health, is primarily a symptom and does not represent a direct cause of tissue damage linked to CW lasers.