Ling, a 75-year-old grandmother, complained that her vision was becoming obscured. Upon examination by an ophthalmologist she wa
s told she had cataracts. What are cataracts, how do they occur, and how are they treated?
a. A cataract is a clouding of the lens. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, diabetes mellitus, or exposure to UV rays over time. The lens can be removed and replaced
with an artificial lens.
b. A cataract is a clouding of the cornea. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, diabetes mellitus, or exposure to UV rays over time. A corneal transplant can be performed to replace the damaged cornea.
c. A cataract is increased intraocular pressure. This occurs when drainage of the aqueous humor is blocked. They are treated with eyedrops that increase the rate of aqueous humor drainage or decrease its production.
d. A cataract occurs when there are unequal curvatures in different parts of the cornea or lens. This is a congenital condition. Specially ground lenses or laser surgical procedures are used to correct this problem.
Answer:a. A cataract is a clouding of the lens. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, diabetes mellitus, or exposure to UV rays over time. The lens can be removed and replaced
Some objects in space are created from clouds of gas and dust. A star forms when the mass of the dust cloud is large and has enough hydrogen to start creating a protostar and sustain the nuclear fusion reaction within the core of the protostar. If the dust cloud is not dense enough, then the star formation does not take place, rather a nebula is formed, example the Horse-head nebula. So the answer is (B) A star will not form.
