<unk>  is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities.<unk> sts are health care professionals who typically provide comprehensive primary eye care. In the United States and Canada,<unk> sts are those that hold a Doctor of<unk>  degree. They are trained and licensed to practice medicine for eye related conditions, in addition to providing refractive (optical) eye care. In the United Kingdom,<unk> sts may also practice medicine (and provide refractive care) for eye related conditions. The Doctor of<unk>  title can also be used in the UK for those that hold the postgraduate O.D. degree. Within their scope of practice,<unk> sts are considered physicians and bill medical insurance(s) (example: Medicare) accordingly. Moreover, many participate in academic research for eye related conditions and disease.<unk> sts are the only health care professionals with a first professional degree specific to eye care; ophthalmologists are physicians who typically hold a four-year college degree, a medical degree, and at least three years of residency training after medical school, obviating the need for an eye-specific degree.
Optometry
Audiometry
Dosimetry
Biodosimetry
Eye chart
Dolorimeter
Snellen chart
Micrographia 