I have myopia and my glasses are -6.50(spherical),-0.75 (Cyl) [Right eye] and -6.00(sph), -1.50(cyl) [left eye]. I am a 23 years old man. I do physical exercises like push ups, sit ups, crunching, etc. Recently I have joined a gym and I am interested to start weight lifting exercises. I have heard that hard exercise can worsen the eye sight of high myopic patients. Should I continue with it? I really want to do those exercises but I don't want my eyes to suffer for that. Please help!
I looked into that on Wikipedia, article here.
Basically the risk would be retinal detachment (which is really, really, bad), for which myopia and doing the valsalva maneuver would be risk factors. Given that I would suggest focusing more on gradually increasing the weight you can lift, and aiming for lower weights - if you can still breathe normally while going up and down (or down and up depending on the exercise), you haven't done the valsalva maneuver, so there wouldn't be any greater risk of retinal detachment than your everyday activities. I would also recommend against pushing yourself to the point where you can barely finish your set - such as in lifting for high endurance. You would want to make sure that your last rep of every exercises is in as perfect form as your first rep.
Don't expect to be able to lift as heavy weights, or as many reps as someone else who's lifting for the same length of time as you.