Yes, it's a factor to cause fatigue of eyes. As we all known, caffeine acts as a stimulant, which is the main integrant of coffee and chocolate that can make us energetic in daily life. However, it would headache as well as cause eyestrain if you intake too much caffeine once, at the same time, it would affect the nervous system.
Caffeine is a stimulant that affects your central nervous system. Most of people take it to refresh when they feel tired. But too much caffeine also do harm to out body including eye health.But caffeine will not cause eye strain itself. However, If you drink too much caffeine, you may feel energetic and work or play for a long time. And the long time of working and playing may cause your eye strain.