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Material dispersion can be a desirable or undesirable effect in optical applications. The dispersion of light by glass prisms is used to construct spectrometers and spectroradiometers. However, in lenses, dispersion causes chromatic aberration, an undesired effect that may degrade images in microscopes, telescopes, and photographic objectives.
removing all the contents of the eyeball during evisceration (complete removal of all structures within the eye in diseases like endophthalmitis: Lid plate: flat large instrument that has a groove and is placed between the lid and globe of the eye to provide a solid support for eyelid surgery Hammer, chisel and bone gouge: bone cutting and shaping
The focal length for light at other visible wavelengths will be similar but not exactly equal to this. Chromatic aberration is used during a duochrome eye test to ensure that a correct lens power has been selected. The patient is confronted with red and green images and asked which is sharper.
A surgical light – also referred to as an operating light or surgical lighthead – is a medical device intended to assist medical personnel during a surgical procedure by illuminating a local area or cavity of the patient. A combination of several surgical lights is often referred to as a “surgical light system”.
In optics, a diffuser (also called a light diffuser or optical diffuser) is any material that diffuses or scatters light in some manner to transmit soft light.Diffused light can be easily obtained by reflecting light from a white surface, while more compact diffusers may use translucent material, including ground glass, teflon, opal glass, and greyed glass.
Corneal cross-linking involves application of riboflavin solution to the eye that is activated by illumination with UV-A light for approximately 30 or fewer minutes. The riboflavin causes new bonds to form across adjacent collagen strands and proteoglycans in the stromal layer of the cornea , which recovers and preserves some of the cornea's ...
When an eye focuses light correctly on to the retina when viewing distant objects, this is called emmetropia or being emmetropic. This means that the refractive power of the eye matches what is needed to focus parallel rays of light onto the retina. A distant object is defined as an object located beyond 6 meters (20 feet) from the eye.
Early symptoms may include strong glare from lights and small light sources at night and reduced visual acuity at low light levels. [4] [5] Couching (lens depression) was the original form of cataract surgery and was used from antiquity. Chrysippus of Soli, a stoic Greek philosopher, provided the earliest account of it. [6]