Just Told Yesterday That 3/4 Of Vision In Right Eye

Just told yesterday that 3/4 of vision in right eye has been lost, but it still seems as if I can see pretty well? Why is this? Also that I will have laser treatment in the next two months, need more info about what laser treatment can do. I am clinical psychologist, 81 years old, didn't retire until 75, but since then seem to be going downhill fast? Thanks for taking time to answer, very helpful to have such a service!!