Eye inflammation is an everyday umbrella term, not a specific diagnosis. Redness can come from the conjunctiva but can also be seen with corneal ulcers, dry eye, foreign objects, inflammation inside the eye or raised pressure. Several of these conditions can look quite similar at home but are treated in completely different ways.
Watch for squinting, rubbing the face, heavy tearing, pus-like discharge, cloudiness or obvious sensitivity to light. The vet can examine the cornea with a dye, measure tear production and check the pressure in the eye if needed. This matters before eye drops are chosen, as some medicines are unsuitable with a corneal ulcer, for example.
Seek care the same day for obvious eye pain, cloudiness, trauma or sudden changes in sight. Do not use old eye drops from a previous occasion without the eye being assessed first.