Let's talk about a few of those causes and see if there is really something we can do to eliminate that root cause and not just mask it. The methods I will suggest will not cost you much, only some time and a little effort. Methods anyone can at least try. When you read these methods they will make sense to you, just like rest and exercise will help other areas of your body.
The number one worst thing we can do to our eyes is to strain them. Society has changed over the years. Looking back years when society was more rural and agrarian more people worked out-of-doors. Our eyes thrived in that environment. They were exercised and moved as they like to.
Today, fewer of us work in that environment. Fewer of us exercise out-of-doors. We go to the gym to exercise more and more. We stay indoors and watch television and spend hours on the computer. Our eyes are not as happy. They don't get the exercise they need and want. They often become tired and strained.