Linked to depression.
Cataracts is the clouding of the eye.
A cataract is a clouding of the lens in the eye which leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression.
Wikipedia, Cataract, 2019
In older adults cataracts is linked to depression.
Cataracts in older adults may be linked to symptoms of depression, according to a new study published in a journal by Optometry and Vision Science. Worldwide, cataract is the number one cause of vision loss... According to the Mayo Clinic, almost half of all Americans in their 60s have some degree of cataracts. Depression, though it can be experienced by people of all ages, is becoming more prevalent in older adults...
Vesan Health, Cataracts In Older Adults Linked To Depression, 2017
Cataracts are linked to depression in the elderly. However this was portrayed in the Quran 1400 years before it was discovered. In the story of Joseph, his father's eyes turned white from sorrow while depressed.
[Quran 12:84] Then he turned away from them, and said, "My bitterness for Joseph." And his eyes turned white from sorrow, and he became depressed.
When his eyes turned white from sorrow he was an old man.
How could an illiterate man who lived 1400 years ago have known that cataracts are linked to depression in the elderly?