In my opinion, the only difference is the fact that opthalmologists perform surgery and optometrists do not. All other training is equal. Optometrists may perform any vision research they choose, which is sometimes associated with the O.D/Ph.D programs available at most optometry schools.
The training is not entirely equal. Ophthalmologists must go through a 4-year residency program after medical school which includes one year of internship (i.e., general medicine). For optometrists, there is no required residency...only the four year graduate program leading to the O.D. degree. Optometrists receive little training in general medicine.
Optometrists are often considered the primary care providers for the eye. Apart from the treatment of refractive errors with glasses and contact lenses, optometrists are trained in many aspects of eye disease and treatment. Ophthalmologists are trained in all those aspects as well, but also in surgery and general medicine. In many states, optometrists are only licensed to prescibe eye drop medications while ophthalmologists are licensed to treat with any medication.
The research aspect is also quite different between the two professions. Optometrists generally do research in vision science and preventive care while ophthalmologists do more clinical and surgical related research.
I'm surprised OD's are limitied to eye drops in some states. In WI OD's can perscribe any medication that can effect the eye. My dad perscribes allergy medications somes times if the allergies cause the eyes to itch. He perscribes drops and pills.
MPPs description of ODs and OMDs is accurate. I might add that although residency is not required, many optometrists do a 1 year residency program after their 4 years in OD school. As mmp said, optometry may be considered primary care. Even primary care practitioners can be specialized, and there is always more to learn about specific areas in optometry if one desires. Residencies are available in pediatrics, low Vision, ocular disease, and specialty contact lens, to name a few.
I agree with mpp's description of the two professions. My blanket statement was probably too big of a blanket, but I do think that the training, though not entirely equal as you described, is comparable. The differences lie in the manner in which students of both professions get to the eye, and to the length of which study of the eye is carried to. OD students dive right in to the eye with ocular specific courses along with several of the general systemic courses that a first year med student would encounter. Are these general courses as rigorous or in-depth as the med school first year courses? I don't know, but many people might be suprised to find out exactly what OD students are required to learn. Of course, opthalmologists are completely trained in general medicine, as they rightfully should be to be performing surgery on the eye. In my opinion, it is the surgery aspect that most distinguishes the professions, and is the basis for my statement. mpp's statement would have been the more appropriate first response to the poster, I'll save my blanket opinions to later posts in the future. I apologize for the confusion, and I will be more specific with my opinions. As far as research, mpp's statement may be a correct generalization, but I believe optometrists research all aspects of vision including clinical, but probably not so much surgical research.
You are correct, TAL.. OD's do clinical research also. I know of quite a few clinical studies that are going on downstairs in clinic right now. But, the major of OD's research (mainly OD/PhD's or just PhD's) centers around vision science and phyisological optics.