Human eye The upper end of the range is given in terms of normal visual performance as 10 cd/m (100,000,000 or one hundred million candelas per square meter). The eye includes a lens similar to lenses found in optical instruments such as cameras and the same physics principles can be applied. The pupil of the human eye is its aperture; the iris is the diaphragm that serves as the aperture stop. Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it
Diaphragm (birth control) IUD and the combined oral contraceptive pill. In 1965, only 10% of U.S. married couples used a diaphragm for contraception. That number has continued to fall, and in 2002 only 0.2% of American women were using a diaphragm as their primary method of contraception. In 2014 Janssen Pharmaceuticals announced the discontinuation of the Ortho-All Flex Diaphragm, making it very difficult for women in the US to have that option as a birth-control method. The single-sized, silicone diaphragm was developed by PATH during the late 2000s. It was licensed to Kessel Marketing & Vertriebs GmbH of Frankfurt, Germany which began to