The writer states that people in modern societies …………

The human eye is nature's most intricate and delicate organ, and upon its development probably rests the high degree of development of man's society. When nature developed this intricate and adaptable organism, human eyes were used primarily for outdoor work and living. With the stress of indoor life and artificial lighting, abnormal strain is placed on eyes today. Sometimes more than nature's assistance is needed to keep eyes in shape for the many uses they serve in modern life. It is also true that we have extended man's normal life span to almost twice what it is in a primitive society. Visual deficiencies also increase with age, and eyes usually need some corrective care as one grows older. Undetected, uncorrected eye trouble can affect the entire personality structure and can make the difference between success and failure in one's working life or personal relations. Theodore Roosevelt, for instance, was slow and backward till it was discovered that his vision was bad. After his defective sight was corrected, he emerged as one of the leaders of his time.