Official Explanation

Argument Construction

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.