What is the difference between an optometrist and ophthalmologist?

If it is just for : New glasses, you can see an optometrist. For most any other eye problem see the ophthamologist. An ophthamologist is an M.D. And can perform surgical procedures, such as for cataracts and more.

Medical doctor: An ophthalmologist is a medical doctor first prior to specializing in the eye. He has to be educated in the entire field of medicine prior to then being trained to diagnose and treat eye problems. In this fashion, an ophthalmologist, unlike an optometrist who is not a medical doctor, can identify systemic diseases when he examines a patient's eyes and deal with it or refer the patient properly.

Medical doctor ophth: An ophthalmologist is a medical docotor and surgeon with the extensive medical and surgical training who unerstands the whole body issues and optics(glasses and contact lenses). An optometrist is train to do a general basic eye exam and optics. Most of the time optometrists refer more advance and complex cases to the ophthalmologist for the care.