I have to ask if you are using the Valsalva Maneuver while lifting the heavy weights. According to the article I linked to, blurry vision is a side effect of taking the Valsalva Maneuver too far. Every lifter is different, and that phenomenon only happens when you are pushing your limits.
The bad news is that as the weight gets heavier, the risk of passing out due to the Valsalva maneuver increases. For bench presses, the safest bet is to press in a power rack with the safety bars above your neck. If you do pass out you won't get injured.
However, it is a useful tool to get those heavy weights up. In some cases its the only way to get those heavy weights up.
You may be able to lessen the impact if you incorporate aerobic exercise after your weight lifting. Aerobic exercise like jogging will help your heart become larger and pump more volume of blood per beat--somewhat easing the circumstances that cause Valsalva retinopathy.