Do you think there's a connection between studying too much and your eyesight getting worse?
Do you think a person's eyesight declines if they spend too much time studying?
この場合、次のような言い方ができますよ。
ーDo you think there's a connection between studying too much and your eyesight getting worse?
「勉強のしすぎと視力の低下に関連があると思いますか？」
Do you think there's a connection between A and B? を使って「AとBに関連があると思いますか？」と言えます。
ーDo you think a person's eyesight declines if they spend too much time studying?
「もし勉強しすぎたら人の視力は低下すると思いますか？」
to decline で「低下する・衰える」
ご参考まで！
カナダ 
