Epidemic is used for some things like obesity, which are not infectious but are increasing. I restrict the use of epidemic to increases of an infectious disease in a particular group of people or particular location.
I am not aware of any infectious cause affecting long-distance eye sight. Of course things like the age distribution of the population (more people are living longer) and the widespread use of screens may well affect the prevalence of vision problems.
There are infectious causes of blindness, but they don’t lead to a loss of distance vision.
It is a natural tendency for our eyes to become more long-sighted as we age, due to the way the muscles that help us to focus age and also because our eye balls change shape.
I’m not aware that there are increasing numbers of people who are near-sighted. It is possible that globally more people are wearing glasses as access to eye tests increases, or a need to see small text up close increases with literacy / gadget use in a population.
Hi A.Lee, this is an interesting question! I hadn’t heard about this before so I did some Googling. It seems that more people now need glasses, and that scientists are not certain as to what is causing this. It may be something to do with our modern lifestyles, but I’m afraid I don’t know any details about this.
Like Christl said, I tend to use the word epidemic for infectious diseases and I don’t think wearing glasses is infectious! But you’re right, it does seem that more and more people are requiring glasses.