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 same law can be applied to determine the oblique illumination due to a lens, assuming a uniform extended diffusing source of light on the other side of the lens. In this case, however, the exit pupil will not in general be a perfect circle because of possible distortion of the iris by that part of the optical system lying between the iris and the image. Also, any mechanical vignetting in the lens will make the aperture noncircular and reduce still further the oblique illumination. In a camera this reduction in oblique illumination results in darkened corners of the picture, but, if the reduction in brightness is gradual, it is not likely to be detected because the eye adapts quickly to changing brightness as the eyes scan over the picture area. Indeed, a 50 percent drop in brightness between the centre and corners of an ordinary picture is scarcely detectable.
Optometrists have a four-year doctoral degree, but they are not medical doctors. Ophthalmologists are medical doctors who specialize in ophthalmology. Ophthalmologists are qualified to diagnose and treat a broader range of medical eye conditions than optometrists, and they can tackle more complex cases. Unlike optometrists, ophthalmologists are qualified to perform eye surgery.
Average Americans work well into their 60s, so workers might as well have a job that's enjoyable and a career that's fulfilling. A job with a low stress level, good work-life balance and solid prospects to improve, get promoted and earn a higher salary would make many employees happy. Here's how Optometrists job satisfaction is rated in terms of upward mobility, stress level and flexibility.
The NBEO will be replacing the slit lamps used for the Part III Clinical Skills Examination (CSE) beginning August 1, 2019 with the Haag-Streit BI900. More information about this slit lamp can be found in the 2020 Site Information and Equipment List for the CSE on our website here. Candidates are encouraged to familiarize themselves with the features of this model.
I came to Standard Optical specifically for a laser surgery consult. My initial consult was with a male optometrist, whose name I can't recall. It was pretty basic and he said it seemed I'd be a good candidate for PRK. I had to do a pre-op appointment here as well, with deep dilation to get good measurements. Everyone was clear that it was possible I would arrive at the surgical center in Holladay and be told that I wasn't actually a good candidate, given my extreme near-sightedness. They told me about the possibility of an ICL surgery, but not much beyond it being more expensive and a lens is inserted. I took away one star because I feel the doctors should have been more careful in telling me I was a good PRK candidate. When I went to down to Holladay on the day of my scheduled PRK procedure, I was told by the surgeon (Dr. Williams) that I was too near-sighted (more than -10) and I would not be happy with the results. He said the doctor at the Ogden location had measured me at just less than -10, which is the cutoff, and that's fine given the different technology they have at the Holladay location. However, if the Ogden doctor knew I was right at the cusp, I would have like to have been told that and used it to make up my mind about scheduling the PRK procedure. I only have one pair of eyes, I probably wouldn't risk it if I was at the extreme edge of permissibly. Also, when they told me about the ICL procedure, all they said was that it was more expensive. Honestly, it felt more like an upsell than a "this procedure could be better for you" discussion. In actuality, once Dr. Williams explained the procedure and pricing to me, the ICL is LESS profitable for Standard Optical (you pay more than LASIK/PRK because of the surgical center fees, the portion to SO is less than the laser procedures).

To ensure the most up-to-date, comprehensive, and contemporary optometric examinations, NBEO constantly reviews content, examination components, and clinical skills as part of its ongoing pledge to public protection and the profession of optometry. This review involves discussions with a wide range of individuals, optometric organizations, and stakeholders. “ARBO is pleased to see NBEO’s evolution of the Part III Clinical Skills Examination to involve more clinical decision making,” said Dr. Richard Orgain, ARBO president. “We look forward to continued collaboration with NBEO as it begins this important task.”


Proposed revisions include knowledge assessments, patient scenarios, and patient record documentation while maintaining a performance evaluation of the most critical clinical skills. With these planned revisions, NBEO will not include any new skills for the upcoming Part III CSE administration beginning August 1, 2018 as previously announced. However, the Injections Skills Examination will only be offered as a stand-alone examination effective August 1, 2018. Updated evaluation forms and all candidate information for the upcoming 2018-2019 testing administration are available as of June 15, 2018.
I came to Standard Optical specifically for a laser surgery consult. My initial consult was with a male optometrist, whose name I can't recall. It was pretty basic and he said it seemed I'd be a good candidate for PRK. I had to do a pre-op appointment here as well, with deep dilation to get good measurements. Everyone was clear that it was possible I would arrive at the surgical center in Holladay and be told that I wasn't actually a good candidate, given my extreme near-sightedness. They told me about the possibility of an ICL surgery, but not much beyond it being more expensive and a lens is inserted. I took away one star because I feel the doctors should have been more careful in telling me I was a good PRK candidate. When I went to down to Holladay on the day of my scheduled PRK procedure, I was told by the surgeon (Dr. Williams) that I was too near-sighted (more than -10) and I would not be happy with the results. He said the doctor at the Ogden location had measured me at just less than -10, which is the cutoff, and that's fine given the different technology they have at the Holladay location. However, if the Ogden doctor knew I was right at the cusp, I would have like to have been told that and used it to make up my mind about scheduling the PRK procedure. I only have one pair of eyes, I probably wouldn't risk it if I was at the extreme edge of permissibly. Also, when they told me about the ICL procedure, all they said was that it was more expensive. Honestly, it felt more like an upsell than a "this procedure could be better for you" discussion. In actuality, once Dr. Williams explained the procedure and pricing to me, the ICL is LESS profitable for Standard Optical (you pay more than LASIK/PRK because of the surgical center fees, the portion to SO is less than the laser procedures).
March 8th is International Women's Day, a day when women are honored and their accomplishments celebrated worldwide. From medicine to law, entrepreneurship to corporate leadership, education to the military, women are achieving great strides in areas of business like never before. In addition to professional achievements, International Women's Day is...

The NBEO will be replacing the slit lamps used for the Part III Clinical Skills Examination (CSE) beginning August 1, 2019 with the Haag-Streit BI900. More information about this slit lamp can be found in the 2020 Site Information and Equipment List for the CSE on our website here. Candidates are encouraged to familiarize themselves with the features of this model.


Optometrists practice in many different kinds of situations and with different types of employers, including hospitals, retail optical settings and the military. Many optometrists set up a private or group practice with one or more other optometrists or with ophthalmologists. Some optometrists decide to go into research at an academic institution or with a corporation. After gaining experience, optometrists may also decide to become consultants to the ophthalmic industry, education, school and/or professional sports and government.

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  .
×