You may need to check your eyes - it could be simple because of eye dryness (sicca) from prolonged gazing onto computer or tablet screens, and this can be managed with adequate eye hydration and rest: artificial tears eye drops applied regularly plus resting your eyes every couple of hours by getting off the computer screens for 15 minutes during which you shut your eyes for a couple of minutes and then try to look at objects at a far distance in order to allow the muscles the pull the lens to relax). The other possibility is that of poor visual acuity for which your vision should be assessed (reading the Snellen chart and eye exam).