How old is your son? Does he have any medical conditions like diabetes or hypertension?
44 years old
high blood pressure
The back lining of the eye is called the retina. This is the layer that receives images and transmit them to the brain for you to see. The center of the retina is called the macula. This is the area responsible for central reading vision and color vision. Sometimes, conditions like high blood pressure, diabetes, hardening of arteries can cause one of the blood vessels going into the retina to get blocked off (like a little stroke). When this happens the blood vessel just leaks blood and fluid into the macula. This causes the macula to swell up (macular edema). This will decrease your vision. Sometimes, the body can absorb this blood and fluid (over several months); and your vision improves. Sometimes, we have to go in and do laser treatments to dry up the blood and fluid.
Hope this helps.