The most common postural problem with desk-sitting and desk-reading is Postural Kyphosis (one type of kyphosis, aka "hunchback"). It is due to a lazy, slouched or slumped sitting posture with the head too far forward and upper back too rounded, but in time it continues as a lazy habit while standing and walking: slightly hunched and with shoulders forward.
In medicine, this posture has been nicknamed "Scholar's Hump" and "Dowager's Hump."
It is bad for your back and terrible for appearance - adds years to your appearance. You can try to strengthen postural muscles by sitting tall with your shoulders back. You have to sit on your "sitz bones," aka ischial tuberosities" and not on your behind. You also have to get rid of the habit of neck-leaning, peering forward or downwards.
Another help can be a straight-backed chair, if you use the back of the chair and resist peering forward.
Another corrective could be a lumbar support cushion or pillow. They keep your spine in a natural position and remind you to sit properly.
If your postural kyphosis is bad enough, add some exercises to attempt to strengthen your core to make it easier to correct it. The best are planks, deadlifts, and weighted squats.
Also, these exercises: Postural Muscles: How to Strengthen Them for a Stronger Back. That article makes the important distinction between postural and phasic muscles.
Ideally, you should be focusing on engaging your postural muscles all the time, regardless of what activity you’re pursuing. Whether you’re working out at home or at the gym, standing in line at the grocery store, or sitting at your desk working, you should make it a point to keep your abs pulled in, your shoulder blades rolling down the back so that your chest is up and forward, and your spine in one line.
