In Norway, the optometric profession has been regulated as a healthcare profession since 1988. After a three-year bachelor program one can practice basic optometry. At least one year in clinical practice qualify for a post-degree half-year sandwich course in contact lens fitting, which is regulated as a healthcare specialty. A separate regulation for the use of diagnostic drugs in optometric practice was introduced in 2004.
To ensure the most up-to-date, comprehensive, and contemporary optometric examinations, the NBEO continuously reviews content and clinical skills as part of its ongoing pledge to public protection and meeting the needs of the optometric profession. As previously announced, the NBEO is excited to embark upon the restructuring of the Part III Clinical Skills Examination (CSE). More information will be forthcoming as this multi-year process develops.
Many types of optical instruments form images by natural light, but some, such as microscopes and projectors, require a source of artificial light. Tungsten filament lamps are the most common, but if a very bright source is required, a carbon or xenon arc is employed. For some applications, mercury or other gas discharge tubes are used; a laser beam is often employed in scientific applications. Laser light is brilliant, monochromatic, collimated (the rays are parallel), and coherent (the waves are all in step with each other), any or all of these properties being of value in particular cases.
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When a ray of light emerges obliquely from glass into air, the angle of refraction between ray and normal is greater than the angle of incidence inside the glass, and at a sufficiently high obliquity the angle of refraction can actually reach 90°. In this case the emerging ray travels along the glass surface, and the sine of the angle of incidence inside the glass, known as the critical angle, is then equal to the reciprocal of the refractive index of the material. At angles of incidence greater than the critical angle, the ray never emerges, and total internal reflection occurs, for there is no measurable loss if the glass surface is perfectly clean. Dirt or dust on the surface can cause a small loss of energy by scattering some light into the air.

The CBOO (Brazilian Council of Optics and Optometry), which is affiliated to the WCO (World Council of Optometry), represents Brazilian optometrists. In conjunction with organizations representative weight of Brazilian companies, including the National Commerce Confederation for goods, services and tourism (CNC), through the CBÓptica/CNC, its defense arm of optometric and optical industry, are defending the right of free and independent practice of optometrists, even if it is against the interests of ophthalmologists.

Because all paraxial rays from a given object point unite at the same image point, the resulting longitudinal distance (l′) is independent of the particular paraxial ray that is traced. Any nominal value for the height of incidence, y, may therefore be adopted, remembering that it is really an infinitesimal and y is only its relative magnitude. Thus, it is clear that the paraxial angles in equation (4) are really only auxiliaries, and they can be readily eliminated, giving the object–image distances for paraxial rays:
"We just love Dr. Bullard. He is so great with my son and we fill 100% confident that he has our best interests at heart. He recently performed surgery on Luke and it went incredibly well. We are thrilled with the great outcome! Top notch Dr. you have there. My son, Luke, has never been fond of dr visits: dentists, pediatricians, etc. but every time we have an eye appt he actually gets excited about going. Nick and Dr. Bullard are both so wonderful with him. He calls them his friends and he now wants to be an eye Dr. when he grows up so he can fix kid’s eyes like they do. This mother could not be more pleased with them!"
However, the German word brille (eyeglasses) is derived from Sanskrit vaidurya.[9] Etymologically, brille is derived from beryl, Latin beryllus, from Greek beryllos, from Prakrit verulia, veluriya, from Sanskrit vaidurya, of Dravidian origin from the city of Velur (modern Belur). Medieval Latin berillus was also applied to eyeglasses, hence German brille, from Middle High German berille, and French besicles (plural) spectacles, altered from old French bericle.[10]
A doctor's professional affiliations and memberships can help to indicate expertise in certain areas of practice; for example, ophthalmologists may belong to the American Society of Retinal Specialists   or the American Society of Cataract and Refractive Surgeons  . Some organizations have rigorous standards for membership or Fellowship, such as the American Academy of Optometry  .