Why do my eyes twitch after looking at a computer screen for more than 15 minutes?

Hi doctor,

I am a 66 year old male, who has a normal eyesight. Last week while I was watching a film on my laptop, suddenly both my eyelids started twitching (fluttering). After that, whenever I look at a computer for more than 15 minutes, the burning sensation starts. The same is true while I read for more than 15 minutes. Even while I type this message, there is twitching in both eyes. I cannot concentrate. I use reading glass + 4.75, and I am not diabetic. However, I have mild tinnitus in both ears from last year. MRI and other tests are normal. At present, I am taking some homeopathic medicine for tinnitus, which is working well. Soon after the twitching started, I had mild watery discharge in both eyes. Now it has stopped. I do not have reddishness in eyes and no butterflies and no black spots. I am in a very remote area, where no medical facilities available. I called a doctor, who is known to us, and he advised to use Refresh tears, one drop in each eye five times a day. I am doing that since last three days, and the burning sensation is a bit eased, but the twitching is the same. While I wake up in the morning, I feel better, as the eyes had rest while I slept. I have no problem with the light, but the eyelid (upper) is vehement when I work on the computer. Please advise. Regards.