3 ms·
Actually you're supposed to look slightly down as far as I can tell. The hard rule seems to be 'just avoid looking up'.
by darklajid 15y ago
Actually you're supposed to look slightly down as far as I can tell. The hard rule seems to be 'just avoid looking up'.
- wyclif 15y agoYes, it's been shown that looking "up" causes increased eye fatigue, since the tear ducts have to work harder. 0-20 degrees below horizontal is optimal.