Final answer:
The cloudiness in the lens of the eye is called a cataract, which causes light dispersion or diffusion leading to blurred vision. Parallel laser light is necessary for precise retinal repairs. After cataract removal, a spectacle lens of about 16 D is typically prescribed for vision correction.
Step-by-step explanation:
The cloudiness of the crystalline lens is called a cataract. When the lens becomes cloudy due to a cataract, it can cause light to be dispersed or diffused, which leads to blurry vision. To address certain eye conditions, such as repairing a tear in the retina, laser light is used in a very precise manner. The rays entering the eye must be parallel to precisely focus on the affected area and effectively 'spot-weld' the retina back onto the back of the eye. If the lens is removed due to cataracts, an individual may need an external lens with about 16 diopters (16 D) to correct their vision since the natural lens is no longer focusing light onto the retina.