In the United States, an optometrist is an eye doctor who has earned the Doctor of Optometry (OD) degree. An optometrist generally must complete a four-year college degree program in the sciences, plus four years of post-graduate professional training in optometry school. In this regard, the educational requirements of an optometrist are similar to those of a dentist.
In the United States, Optometrists examine eyes for both vision and health problems, and correct refractive errors by prescribing eyeglasses and contact lenses. Some optometrists also provide low vision care and vision therapy.
Optometrists in the United States also are licensed to prescribe medications to treat certain eye problems and diseases. The scope of medical care that can be provided by optometrists is determined by state law. (For details about the scope of practice of optometrists where you live, visit the website of your state's board of optometry.)
As stated above, in the USA all optometrists have a license granted by the state. This sets the limits or scope of what the optometrist may treat. Over time, the optometry field has expanded and grown to include specialization or a focus in a certain aspect of care. An optometrist may focus on:
A focus on the first 3, pediatrics, vision therapy/binocular vision, and neuro-optometry have a significant amount of overlap. Optometrists that work in this field are sometimes referred to as a developmental optometrist, vision therapy optometrist (VTOD), or neuro-optometrist. The type of patient addressed by optometrists in this field is quite diverse - but often these patients struggle with binocular vision for some reason or another. This could be due to amblyopia, strabismus, vergence disorders, a traumatic brain injury, visual processing disorder, and others.
Optometrists that focus on specialty contact lenses often work with difficult contact lens cases. Quite often their patients have some sort of irregularity to the cornea, the front, clear window tissue of the eye. This could be due to a disorder such as keratoconus, pellucid degeneration, or other corneal diseases, or could be due to trauma from an accident or surgery. Although the vast majority of optometrists fit contact lenses, optometrists that work with patients such these often use specialty-made lenses called scleral or semi-scleral. These are really large, hard contact lenses that are fit to vault (or rise over) the damaged tissue and fit on the white part of the eye (the sclera). The lens is filled with saline, which is then mixed with tears over the course of wear. This, in essence, creates a new surface for the visual system when the patient is wearing the lens and can make a big difference in some patient's vision.
Many optometrists are capable of diagnosing, managing, and treating disorders of the eye. Some optometrists work in clinics that focus primarily on ocular disease - and as you can imagine, geriatric care. Many of these optometrists work together with ophthalmologists, or may work in hospital or Veteran's Affairs clinics that treat a higher proportion of sick eyes.
In short, there's no one test that makes an optometrist a specialist. Sometimes all it takes is years of experience! However, in recent years optometry has adopted a medical-model of additional training after 4-years of optometry school. This extra training is often a one-year long residency in a specific focus as listed above.
You may also see some additional letters behind an optometrist's name (besides the OD that stands for doctor of optometry). Some common additional letters are:
FNORA: a fellow of the Neuro-Optometric Rehabilitation Association - these optometrists have completed a fellowship with the Neuro-Optometric Rehabilitation Association, which consists of case presentations, review, and an oral examination; often these optometrists work within a vision therapy/binocular vision/neuro-optometry setting