Final answer:
Cataracts are graded using systems like the LOCS III, and they can disperse light, causing blurred vision. Parallel laser rays are used in eye surgery to precisely target the retina without damaging nearby areas.
Step-by-step explanation:
Cataracts are a medical condition characterized by the clouding of the lens in the eye, which can lead to decreased vision and potential blindness. Cataracts need to be graded to understand their severity, which is typically done using a classification system that looks at various aspects such as the density of the lens opacity and its impact on vision.
One common grading system is the Lens Opacities Classification System III (LOCS III), which utilizes slit-lamp images to grade the intensity of the cataract on a scale. The condition may diffract or disperse light rather than transmitting it directly, leading to blurred vision.
For surgical procedures such as the repair of a retinal tear using laser light, it is crucial for the rays entering the relaxed, normal-vision eye to be parallel. This is because parallel rays will focus correctly on the retina, allowing precise spot-welding required for the repair without damaging surrounding tissues.