Which organ's focusing and imaging properties make it particularly susceptible to laser damage, and it lacks pain sensory nerves?

Which organ's focusing and imaging properties make it particularly susceptible to laser damage, and it lacks pain sensory nerves?

• A. Retina
• B. Cornea
• C. Eye
• D. Lens

Answer: (C)

The main idea is that lasers threaten the tissue that ends up bearing the focused light image. Light entering the eye is bent by the cornea and focused by the lens to form a sharp image on the retina, a tiny spot where the neural signals are generated. Because a laser can deposit energy into that small retinal area, the energy density can be high enough to cause photothermal or photochemical injury even at relatively low exposure levels. The retina is also notable because it lacks pain-sensing nerves, so damage can occur without any sensation to warn you. This combination—eye optics concentrating light onto a small retinal region and the retina’s lack of pain receptors—makes retinal damage from lasers particularly dangerous. In contrast, the cornea has abundant pain fibers, so corneal exposure is likely to be painful, and the lens, while involved in focusing, does not form the image where tissue damage would be detected in the same way.

The main idea is that lasers threaten the tissue that ends up bearing the focused light image. Light entering the eye is bent by the cornea and focused by the lens to form a sharp image on the retina, a tiny spot where the neural signals are generated. Because a laser can deposit energy into that small retinal area, the energy density can be high enough to cause photothermal or photochemical injury even at relatively low exposure levels. The retina is also notable because it lacks pain-sensing nerves, so damage can occur without any sensation to warn you. This combination—eye optics concentrating light onto a small retinal region and the retina’s lack of pain receptors—makes retinal damage from lasers particularly dangerous. In contrast, the cornea has abundant pain fibers, so corneal exposure is likely to be painful, and the lens, while involved in focusing, does not form the image where tissue damage would be detected in the same way.