Answer:

When eyes are exposed to lenses with multiple prescriptions such as varifocals, multifocals or progressives for the first time, it can take a while for the brain’s visual center to become adjusted.
 

If you are new to any of these types of lenses, it can take up to three weeks for your eyes to become fully adjusted to your new optics. The best and fastest way for your eyes to adapt to your improved vision is to wear your glasses consistently. If you are experiencing severe problems, start by only wearing your progressive lenses while you are seated. Then over time, you can start to incorporate them into everyday movements, such as climbing stairs, playing sports and eventually driving. 

A few other techniques you can use to adjust your eyes are: 

1) Move your head up and down to look through different areas of the lenses to focus on objects that are at different distances. This will help your brain understand better your lenses.

2) Look straight ahead to focus your eyes on objects that are far away

3) Look through the bottom of the lenses to focus your eyes on objects that are close to you

4) Turn your head and point your nose where you want to look. The optics in bifocals are vertically aligned so turning your head to face objects will improve your vision. 

5) Be patient –because adjustment periods are different for everyone.