What percent of the pre-modern world was blind?

Factual Questions
1

In 2010, about 289 million people had visual impairments (4% of world population) and 39 million were blind (about 0.2%). Numbers per: https://www.who.int/blindness/publications/globaldata/en/#:~:text=Globally%20the%20number%20of%20people,blindness%20is%20cataract%20(51%25). The larger number is those with “low vision” presumably affecting daily life and not correctable by ordinary glasses.

There are a lot of medical conditions that can cause blindness if not treated, which we now can control in the ordinary course of medicine - scarlet fever comes to mind. Some people still go blind from diabetes but before treatments for that condition were developed in the 20th century, many more people with diabetes would have suffered the full consequences of the illness. Cataract surgery has existed since ancient times but was not as reliable or available to non-elites as it is today.

I can’t find a scholarly accounting of what percentage of people in, say, ancient Rome, or 18th century Europe, were blind. What would be a good method to estimate this, if no one has already done so?

2

Diabetes was much less of a problem until recently, but smallpox frequently caused blindness by scarring the corneas. Things like trachoma could end in blindness, and even minor accidents could result in impaired vision due to a lack of suitable treatment, But, given the lack of reliable figures for just about anything in the premodern world, I think we can only say “more than today.” You could of course get some idea from the statistics from places such as rural Afghanistan.

3

People also went blind from conditions like glaucoma and cataracts that can be controlled now, but still cost people their vision in Third World countries. Safety standards at home and in industry weren’t what they are now, either.

Example: There’s a living-history village in the next town over, and that includes a blacksmith shop where they all use period tools, with one concession: They wear safety goggles. The shop has a sign stating that old-fashioned blacksmiths did not usually use eye protection, but modern safety standards required this.