There is an eye disease called “macular degeneration”. My father has it, as do many, many other people. Normally a person with “macular” will lose their sight slowly over time, with each week being a little darker than the week before. It is only one of many eye illnesses which can cause eventual blindness.
As terrible as it is, what about ‘spiritual blindness’, especially what I call ‘practical-spiritual blindness’? It’s the inability for a person to recognize the love of God in the midst of deep personal pain, or inability to see the miraculous work of God or the miraculous timing of God in the circumstances of life.