Final answer:
A morganian cataract is an advanced type of cataract characterized by the liquification of lens proteins and significant vision impairment. Cataracts disperse or diffuse light, causing visual disturbances. Laser used in eye surgery requires parallel rays to accurately repair a retinal tear without damaging other eye structures.
Step-by-step explanation:
A morganian cataract is a type of advanced cataract where the lens proteins have become completely liquified, causing the denser proteins to settle to the bottom, resembling a snow globe. This type of cataract can cause significant vision impairment because it leads to cloudiness in the lens of the eye. Regarding the question about how a cataract affects light, cataracts generally cause light to be dispersed or diffused, creating visual disturbances such as blurring and sensitivity to glare.
Concerning the use of laser light for repairing a retinal tear, the rays entering the eye must be parallel for precision. Parallel rays ensure accurate focusing and spot-welding of the retina without damaging other parts of the eye. This precision is crucial for the success of the repair procedure and maintaining the health of the eye.