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  3. The retinas of premature babies are not fully developed at birth. Because their

The retinas of premature babies are not fully developed at birth. Because their

游客2024-01-12  34
问题 The retinas of premature babies are not fully developed at birth. Because their retinas are so delicate, premature babies sometimes lose their sight. Methods for preventing this syndrome, which is called retinopathy of prematurity, have improved, but the proportion of premature babies who lose their sight because of this syndrome has increased.
Which of the following, if true, best reconciles the apparent discrepancy described above?
选项 A、When premature babies are born, their retinas are developmentally unprepared to deal with light and air in the environment outside the womb.
B、The oxygen that must be administered to premature babies at birth can sometimes have a damaging effect on the babies’ retinas, but the oxygen is now administered in less damaging concentrations than it used to be.
C、The effects of retinopathy of prematurity can be reduced by controlling the exposure of premature babies to light and oxygen, but this method cannot completely prevent the syndrome.
D、The improvement of methods to prevent retinopathy of prematurity has been a gradual process, and there is still a need for further knowledge.
E、Improved medical technology is saving the lives of premature babies who would previously have died, but these babies have even more delicate retinas than do other premature babies and are more apt to lose their sight.
答案 E
解析 What could reconcile the fact that, even though technology has improved the likelihood of saving premature babies sight, a greater percentage of premature babies are losing their sight than in the past?
Retinopathy of prematurity (ROP) can lead to blindness in babies born prematurely. However, methods for preventing ROP have improved. Given that, it is puzzling that the proportion
of premature babies who go blind due to ROP has increased.
It is important to carefully distinguish among three different groups: the proportion of premature babies who survive; the proportion who have ROP; and the proportion of those who have ROP who become blind as a result.
A change in the proportion of premature babies that have ROP does not necessarily imply a similar change in the proportion of ROP cases that lead to blindness. Thus, even with an increased survival rate of premature babies and improved prevention of ROP, a greater proportion of babies with ROP can go blind.
For example, suppose the severity of ROP at birth among surviving premature babies is greater. Then we could expect that a greater proportion of ROP cases would lead to blindness, absent a measure to prevent this occurring.
A    This choice does not explain why a greater proportion of ROP cases lead to blindness; it simply suggests some of the conditions in prematurity that can cause retinopathy.
B    This choice does not resolve the apparent contradiction described; it merely suggests one factor that can damage premature babies’ retinas.
C    This choice does not resolve the apparent contradiction; it merely indicates how some severe consequences of ROP may be moderated.
D    This choice does not resolve the apparent contradiction; it merely indicates that there is more for medical science to discover about how to prevent or treat ROP.
E    Correct. Among the ROP cases that
currently occur, a significant number of them are more severe than in the past. This is an indirect result of the increased survival rate of premature babies, which is also due to technological advances. The greater severity of the ROP among those babies who have it could easily explain the greater proportion of ROP cases that lead to blindness.
The correct answer is E.
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