The intelligence level of the average adult decreases with age. The same is true of visual function, which also decreases as we get older. A review of published literature shows vision impairment corresponds with cognitive deterioration and aging. So, German researchers set out to see whether a link between the two existed. Specifically, does restricted vision at least partially explain age-related reduction of intelligence?

The researchers conducted a controlled, longitudinal study among five groups of senior citizens who have cataracts. The participants were divided into two categories, those who would undergo cataract surgery and those who would not. Intelligence testing prior to surgical intervention showed that cataract patients achieved lower than normal levels of mental efficiency when compared with the average population.

But a few weeks after IOL implantation, these patients showed statistically significant increases in tested intelligence levels, while the control group showed no change.

The researchers concluded that surgical removal of cataracts may have a considerable effect on the patients I.Q.

Gertsmeyer K, Lehrl S. [Cataract-related changes of intelligence. An innovative aspect. Ophthalmologe 2004 Feb;101(2):158-63.