Final answer:
The three types of multifocal contact lens designs are Bifocal, Trifocal, and Progressive, which enable vision at multiple distances. Cataracts disperse light, leading to diffused vision. Laser light used in eye surgery must be parallel for precise focusing during retinal repair.
Step-by-step explanation:
The three design types of simultaneous vision designs for multifocal contact lenses are: a) Bifocal, Trifocal, and Progressive. These designs allow a person to see at multiple distances simultaneously, by having different lens powers incorporated into one lens. For example, a bifocal contact lens will have two prescriptions in the same lens – one for close-up vision and another for distance.
A cataract is cloudiness in the lens of the eye, which causes light to be dispersed or diffused. This dispersion disrupts the clarity of vision, causing a diffuse, sometimes blurry image to be perceived rather than a sharp one.
When laser light is used to repair a tear in the retina, the rays entering the eye must be parallel to ensure that the light focuses precisely on the intended spot without diverging before it reaches the retina. This precision is necessary for effective spot-welding during the retinal repair procedure.