Would history be different if Messier had poor eyesight?

I was contemplating the idea of historical astronomers being able to identify deep space objects with relatively good precision. The fact that they lacked electronics, such as good camera sensors, semi-conductors, and computers - but were still able to pave the way for many frameworks and methods we use today is truly incredible.

Being someone who wears contact lenses and glasses, I've often wondered how my life would be if I was born in to an earlier time. Or perhaps if I was somehow to survive an apocalypse but lost my glasses. This is something we take for granted now, but being without corrective lenses is really a disability. Though other historical accounts exist, the first wearable eyeglasses appeared around 1284 attempting to correct for hyperopia (i.e., farsightedness). However, eyeglass frames with corrective lenses (e.g., spectacles) were invented in 1727. It wasn't until 1825 when Cylindrical lenses used to correct astigmatism, thanks to the invention by Sir George Airy.

Charles Messier lived from June 26th, 1730 to April 12, 1817. He was a French Astronomer and wasn't necessarily wealthy or upper class. In fact, he joined the French navy at a younger age. So can we assume that he either had (1) near perfect eyesight, (2) perfect eyesight, or (3) access to these newly created inventions which probably varied in their precision for correcting eyesight? It's hard to tell, but we can speculate.

It turns out that in most cases, someone without perfect vision can look through an optical telescope without their glasses on and adjust the telescope so they end up with 20/20 vision. Unless they have an astigmatism, and in that case they probably aren't able to adjust to perfect vision with the telescope alone. Since Messier died before 1825, we can assume that he either didn't have an astigmatism or that he had one and managed to conduct his work in tolerance of it.

Image Credit: Ansiaux (1729—1786) (??) - Stoyan R. et al. Atlas of the Messier Objects: Highlights of the Deep Sky. — Cambridge: Cambridge University Press, 2008. — P. 15.

"Arizona optical designer Richard Buchroeder devised this handy rule. If the amount of “cylinder” (in diopters) in your eyeglass prescription is D, you can remove your eyeglasses whenever the telescope’s exit pupil (in millimeters) is 1/√ D or smaller. A larger exit pupil means your uncorrected eye will contribute more than 1/4 wave of aberration, and image quality will noticeably suffer. Let’s say your eye needs a cylinder correction of 0.7 diopter (which is not much). The maximum exit pupil is then 1/√0.7, or 1.2 mm. Since the diameter of the exit pupil equals the aperture divided by the magnification, you’ll be able to use a 4-inch (102-mm) telescope at 85× or higher without wearing glasses." - Credit, Gary Seronik, Sky and Telescope

Here's something to ponder: What if Messier had poor eyesight, and continually obtained corrective lenses that were imbalanced - never allowing him to see the same clarity that others with perfect eyesight took for granted. Yet, the only time he could see with perfect eyesight was when he looked through a telescope.

That has had me smiling nonstop since I thought about it. Hope the idea brightens your day.

- Ira Bell, Founder @ Space Elements