Hi ..it is subconjunctival blood. Happens with minor trauma, BP, in patient with blood thinners etc.. If no decrese in vision, get BP checked, that should be fine. If you have not checked eyes for sometime, better to check once ....to rule out no bleeding inside . It will go in couple of weeks , doctor can prescribe some meds.

This can be because of sudden shoot up of BP if he is hypertensive or because of accidental trauma to the eye with the finger unknowingly. If he is on blood thinners, it can lead to this kind of picture at times. The increase in redness is actually the spreading of the clotted blood. No need to worry.