The word cataract actually refers to waterfalls, or any sudden downpouring of rain. The first use of the word in reference to the common visual malady came as a description. Patients often said their vision slowly began to develop the appearance of a waterfall coursing through it.
Initially, patients may not notice cataracts, but gradually will experience a milkiness or clouding of their vision. Imagine looking through glass that is slowly being fogged over by your breath. In time, it becomes more difficult to see at night, and then to read, and then to distinguish anything but vague lights and shapeless colors.
This is a natural occurrence, but just because middle age means things start to get a little foggy, it doesn’t have to mean it stays that way. Middle aged should mean you have half of your life left to see.