But that is not the only reason. The process of reading up close requires a muscular effort. People who challenge the muscle may have what are called spasms of accommodation. Working in front of a computer also may induce other serious problems. Dr. Ronald Burd, director of ophthalmology at Albert Einstein College of Medicine-Montefiore Medical Center in the Bronx, said that computer monitors could occasionally trigger ocular migraines.
Some people are sensitive to red wine or blue cheese.
Some small group of people who have migraines are very sensitive to the computer. I think perhaps the rhythmicity of the pixels in the display stimulates them. Many optometrists view computer-related vision problems as a form of repetitive stress injury. Just like other forms of RSI, the problems take time to develop and lots of time for recovery. If I give a piano player glasses suitable for reading a book, the glasses won't work - he'll have to lean forward to get the score in focus.