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In normal use, a much smaller section of the lens is used, so that the distortion is much smaller. Progressive lenses are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors.
The refractory period in cardiac physiology is related to the ion currents that, in cardiac cells as in nerve cells, flow into and out of the cell freely. The flow of ions translates into a change in the voltage of the inside of the cell relative to the extracellular space. As in nerve cells, this characteristic change in voltage is referred to ...
Refractory period (sex) In human sexuality, the refractory period is usually the recovery phase after orgasm, during which it is physiologically impossible for males to have additional orgasms. [ 1][ 2] This phase begins immediately after ejaculation, and lasts until the excitement phase of the human sexual response cycle begins anew with low ...
The vitreous body lies at the back of the eye, between the lens and the retina. The vitreous body ( vitreous meaning "glass-like"; from Latin vitreus 'glassy', from vitrum 'glass' and -eus) is the clear gel that fills the space between the lens and the retina of the eyeball (the vitreous chamber) in humans and other vertebrates.
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.
Adaptation (eye) In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher ...
Eye examination for visual acuity. Visual acuity is a measure of the spatial resolution of the visual processing system. VA, as it is sometimes referred to by optical professionals, is tested by requiring the person whose vision is being tested to identify so-called optotypes – stylized letters, Landolt rings, pediatric symbols, symbols for the illiterate, standardized Cyrillic letters in ...
“There’s certain things you shouldn’t do right away but as soon as that time period is over, I feel pretty normal,” he says. “I have a pretty active job … I go right back to it.”