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6-APA ((+)-6-aminopenicillanic acid) is a chemical compound used as an intermediate in the synthesis of β–lactam antibiotics. The major commercial source of 6-APA is still natural penicillin G. The semi-synthetic penicillins derived from 6-APA are also referred to as penicillins and are considered part of the penicillin family of antibiotics ...
The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light. [2] In some cases caustics can be seen as patches of light or their bright edges, shapes which often have cusp singularities .
Refractive results using power calculation formulae based on pre-operative biometrics leave people within 0.5 dioptres of target (correlates to visual acuity of 6/7.5 (20/25) when targeted for distance) in 55% of cases and within one dioptre (correlates to 6/12 (20/40) when targeted for distance) in 85% of cases.
Common causes of scotomas include demyelinating disease such as multiple sclerosis (retrobulbar neuritis), damage to nerve fiber layer in the retina (seen as cotton wool spots [3]) due to hypertension, toxic substances such as methyl alcohol, ethambutol and quinine, nutritional deficiencies, vascular blockages either in the retina or in the optic nerve, stroke or other brain injury, and ...
A Royal Canadian Sea Cadet looks through a machine gun sight.. A sight or sighting device is any device used to assist in precise visual alignment (i.e. aiming) of weapons, surveying instruments, aircraft equipment, [1] [2] optical illumination equipment or larger optical instruments with the intended target.
The optic radiations, one on each side of the brain, carry information from the thalamic lateral geniculate nucleus to layer 4 of the visual cortex. The P layer neurons of the LGN relay to V1 layer 4C β. The M layer neurons relay to V1 layer 4C α. The K layer neurons in the LGN relay to large neurons called blobs in layers 2 and 3 of V1. [26]
Scientist using an optical microscope in a laboratory. The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects.
Retinal migraine is associated with transient monocular visual loss in one eye lasting less than one hour. [1]During some episodes, the visual loss may occur with no headache and at other times throbbing headache on the same side of the head as the visual loss may occur, accompanied by severe light sensitivity and/or nausea.