Category: P
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Preformed scleral lens
A scleral contact lens which is fitted by means of a diagnostic lens set, not requiring the taking of an impression of the eye.
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Pinhole lens
A contact lens (usually corneal) which is opaque except for a central aperture of 1-2 mm. in diameter; it can be used in presbyopia and in some cases of subnormal vision.
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Piggy-back bifocal
A half moon shaped contact lens which constitutes the reading add when fitted in conjunction with an ordinary single vision contact lens.
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Photokeratoscope
A keratoscope provided with a camera, used to photograph the keratoscopic pattern reflected from the cornea.
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Photo-electronic heratoscope
A photokeratoscope provided with a camera, used to photograph the keratoscopic pattern reflected from the cornea, and having an auxiliary device for use in analyzing the photograph electronically.
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Phoria
The direction or orientation of one eye with respect to the other, when fusion is interrupted.
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Peripheral curve
The most peripheral curve on the back surface of a contact lens, usually having a radius of curvature from 9.50 mm. to 12.25 mm., and a width from 0.2 mm. to 0.5 mm.
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Palpebral fissure
The region between the upper and lower eyelid margins within which can be seen, when the lids are open, the eye and adjacent structures. The opening separating the upper and lower eyelids.
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Peak bone mass
The amount of bone mass a person has when the skeleton fully matures and the bones have reached their maximum density and strength.
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Porosity
The hair’s ability to absorb and retain moisture. Hair that doesn’t retain moisture has a lot of porosity. Porous hair is extradry and normally full of frizz. Hair that has been through too much heat-tool styling or chemical treatments is most prone to being porous. It doesn’t look healthy. State of allowing liquids to flow…