Final answer:
A progressive loss of transparency of the lens of the eye is termed a a. cataract. This condition causes clouding of the lens and can result in vision loss unless treated by replacing the lens. Laser eye procedures require rays to be parallel to accurately focus on the retina.
Step-by-step explanation:
A progressive loss of transparency of the lens of the eye is known as a a. cataract. Cataracts are a clouding of the lens that allows light into the eye, which can lead to a loss of vision. Treatment for cataracts typically involves replacing the cloudy lens with a plastic lens, which is a straightforward and successful procedure.
When laser light is used to repair a tear in the retina, the rays entering the eye must be parallel to ensure accurate focusing on the retina without being diffused by the eye's natural focusing system. This is essential for procedures like spot-welding the retina to the back of the eye.
It is also important to note that repeated exposure to UV-B radiation can lead to cataract formation, highlighting the need for proper UV eye protection, such as wearing sunglasses made of plastic, which are more effective at blocking UV rays than those made of glass.