In most cases, genetics is the main cause for eye issues. Most common for aging are cataracts. This clouding of the lens of the eye can cause blindness if left untreated. Keeping in mind that cataracts are not treated surgically until deemed necessary, at which time your eye doctor will schedule to have the lens replaced and sight is improved.
One man does not see everything.
Greek Proverb
Diabetics have a higher risk with the health of their eyes, and this can have a greater effect on the treatment of their diabetes. In both instances, it is best to have a yearly eye exam. If corrective devices are needed, like contacts or glasses, please ensure that you are using them as prescribed. It is for your benefit and will make the world a lot easier to see and navigate.