The redness of the cat’s orbital rim may be caused by inflammation, irritation, improper diet, internal heat, allergies, or bacterial infection. You can use saline to rinse the cat’s eyes, improve its diet, and feed it some light food. Cats, observe for a few days to see if there is improvement. If not, it is best to take the cat to the pet hospital for examination to avoid worsening of the condition and affecting the cat's health.