A cross-sectional study of the relationship between blood type and the risk of cataracts may produce misleading results because you cannot tell the correct temporal relationship between the exposure (blood type) and disease (cataracts). True or False?

Answer: True

Explanation:

A cataract is a clouding of the lens of your eye. As one ages, proteins in the lens begin to break down and the lens becomes cloudy. One may not even realize they have a cataract because it usually grows very slowly and may not impede vision early on. While cataracts are rarely dangerous, after a number of years they will likely affect vision. Its important to note also that cataract is not caused by overuse of the eyes and it does not travel from one eye to the other.

Risk factors include aging, family history, high blood pressure, previous eye injury, smoking, obesity, heavy drinking and diabetes.

Therefore, from the above risk factors, we could expound that blood type (exposure) has no relationship with cataract.