Redness in the eyes may be due to allergies.
It can be related to dry eye.
Dryness can cause the surface of the eyes to become inflamed and blood vessels to dilate, causing increased redness.
Prolonged use of AC,computers,TV etc can result in dryness in eyes.
In some cases redness in eye can be due to infection(Viral or bacterial)
As such you should consult your doctor for further diagnosis and management.
The line of treatment may include
Antihistaminic eye drops.
If infection is suspected antibiotic eye drops may be advised.
I hope this helps