Noticing Newbies

Hello Everyone,

I'm new here and before attempting any writing I'm curious about everyone's reading capacity.
Specifically how long can you read before your eyes get fatigued or irritated ?

I ask because up until age 30 I could read (or read and write, the two being inseparable) for much longer than I can now at age 71.
Younger me would read late into the night before bed, often after several hours of schoolwork.
Now I've given up reading after dark, it's too likely too cause next-day irritation.
I've had regular eye checkups by the eye professionals: (ophthalmologist and optometrist) and physically all is OK.

Everyone, young or older, feel free to chime in with your status and any suggestions (artificial tears, blue-blockers, etc) .

Thanks,
Agnosticus