If not used properly, steroids can cause glaucoma - a disease that raises the pressure in the eye, damaging the optic nerve and causing permanent vision loss that starts with the peripheral vision and works its way to the center I've seen this problem in my clinic and it is the last thing that a patient expects. The only way to catch it before it's too late is to see your optometrist for an eye exam.
There are so many things that can sneak up on your health. People need to see their doctors (not just optometrists) regularly so that issues like this can be nipped in the bud. I bet dentists could tell similar stories. Another point is that doctors shouldn't stray beyond their comfort zone or level and area of expertise. When in doubt, refer the patient.
Eye drops image courtesy of marin / FreeDigitalPhotos.net.