An ophthalmologist is either a medical doctor (MD) or an osteopathic doctor (DO). They provide comprehensive eye care. This includes exams, diagnosis, and treatment for many eye disorders. They are skilled in all types of eye care. They can prescribe eyeglasses and contact lenses, as well as do complex eye surgery. Many also specialize in one disease or part of the eye (such as glaucoma specialist or cornea specialist).
An optometrist is a doctor of optometry (OD) who specializes in eye care. They give exams, and diagnose and treat many eye disorders. They don’t often do surgery. But in a few states they can do minor surgical procedures and laser surgery. Some specialize in low vision, contact lenses, or vision rehabilitation.
An optician is a technician. They fit, adjust, and fill the prescriptions for eyeglasses and contact lenses prescribed by ophthalmologists and optometrists.
An ocularist is a skilled professional. They make and fit artificial eyes (called prosthetic eyes or ocular prostheses). They also give people instructions on how to care for their prosthesis.