could the long hours - developers spend staring at glaring screens,
result in them needing specs?
these breed look at tubes more than couch potatoes.
is it inevitable? like if one does this thing for 20 years ?

sacrifice to make for hardcore programmers, Most Programmer Ended up Using Glasses But Who Cares ALmost Every Body Need Glasses at some Certain Age,

NOpe. might not if you take care of yourself well. The older generation didnt know the hazards of the profession hence the glasses and the RSI (Repetitive Strain Injury). Nowadays we treat ourselves better. there's info available on the web for preventing that.

You have nothing to fear.

It is well.

Tip : If you notice you are unable to coup with the screen, there are screen filters out there you can purchase and use. Also Try purchasing for yourself a very good pair of sunglasses, preferably one with UV100 filters. Where them when you are outside and when working in front of your computer(anytime you start to feel the strain on your eyes). I started doing that a couple of years ago and I now spend so many hours in front of my machine without even pain.