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Related to darkfield illumination: Dark field microscopy


1. the lighting up of a part, cavity, organ, or object for inspection.
2. the luminous flux per unit area of a given surface; SI unit, lux. Symbol E.
darkfield illumination (dark-ground illumination) the casting of peripheral light rays upon a microscopical object from the side, the center rays being blocked out; the object appears bright on a dark background.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


1. Throwing light on the body or a part or into a cavity for diagnostic purposes.
2. Lighting an object under a microscope.
[L. il-lumino, pp. -atus, to light up]
Farlex Partner Medical Dictionary © Farlex 2012


1. The action of brightening an object with light. 2. The science of the application of lighting. 3. Synonym for illuminance.
diffuse illumination In slit-lamp examination, it is the illumination obtained with a wide slit and an out of focus beam or with a diffuser, thus providing an overall view of the structures of the eye.
direct illumination In slit-lamp examination, the slit beam and the microscope are both focused sharply on the structure to be observed. Syn. focal illumination.
focal illumination See direct illumination.
indirect illumination In slit-lamp examination, the slit beam is focused on a structure located adjacent to the structure to be observed.
inverse square law of illumination See inverse square law of illumination.
oscillation illumination In slit-lamp examination, it is a technique in which the beam of light is oscillated to provide alternative direct and indirect illumination. It sometimes allows one to see slight changes more easily which otherwise would remain unnoticed under sustained illumination of either kind.
retinal illumination See retinal illuminance.
retro-illumination In slit-lamp examination, it is a method of illuminating a structure by using the light that is reflected by the iris or an opaque or senescent lens. This method is closely related to indirect illumination and often in corneal examination part of the cornea will simultaneously be under retro- and indirect illumination. Syn. transillumination. See central corneal clouding; oedema.
sclerotic scatter illumination In slit-lamp examination, it is a method in which the beam of light is focused on the sclera near the limbus and the cornea remains uniformly dark in the absence of an opacity. However, an opacity in the cornea becomes easily visible as it scatters light. See central corneal clouding; oedema.
specular reflection illumination In slit-lamp examination, it is a method in which the beam of light and the microscope are placed at equal angles from the normal to the corneal or lens surface to be viewed. This is a method for examining the quality of a surface. This method is particularly useful to observe the corneal endothelium. See endothelial blebs; cornea guttata; shagreen.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann


Throwing light on the body part or into a cavity for diagnostic purposes.
[L. il-lumino, pp. -atus, to light up]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about illumination

Q. Is it true that is places with less sun light people tend to be more depressed?

A. that is correct- a good friend of mine moved to north Alaska about 3-4 years ago. in the winter they hardly have sun. then some of the people get depressed. the treatment is pretty funny- they have to move around with a hat with an illumination system shining over their eyes. they think that the lack of sun light causes a lack of certain chemicals in the brain.

Q. My husband has psoriasis and the dermatologist suggested that he try the uv light treatment.Anyone try it. some of the side effects may be skin cancer and melanoma's. If so can you please let me know if it actually did help or if not. Thanks a million.

A. uv light treatment procedure is relatively new mod of treatment so here is difficult to build an opinion about it.
Actually there are two main type of treatment relating uv light are in use one is uvb treatment and other one is PUVA (uva light based).
As uvb is the most prominent factor for skin cancer so this treatment is more risky. While PUVA is quite effective treatment and has less side effects.

Q. I had cataract surgery with iol implant, and ever since I have awful light sensitivity. Any ideas? I can't go into a "super store" without my sunglasses. My eyes ache at the end of the day. My doctor says "I don't know!"

A. May sound a bit silly question, but have you tried to consult your ophthalmologist (eye doctor, e.g. the one that performed the operation) about it? Cataract surgery, although considered very successful, isn't problem-free. Primary physician may not have the necessary specialization to deal with these subjects.

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