allowance


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allowance

 [ah-low´ans]
something permitted or allowed.
recommended daily allowance term popularly used as a synonym for recommended dietary allowance.
recommended dietary allowance (RDA) the amount of nutrient and calorie intake per day considered necessary for maintenance of good health, calculated for males and females of various ages and recommended by the Food and Nutrition Board of the National Research Council. See Appendices 4 and 5. Popularly called recommended daily allowance.

al·low·ance

(a'low-antz),
1. Permission.
2. An allotted portion.

allowance

The allocation of a thing on a routine basis.

al·low·ance

(a'low-ans)
1. Permission.
2. An allotted portion.

retinoscope 

An instrument for determining objectively the refractive state of the eye. It consists of a light source, a condensing lens and a mirror. The mirror is either semi-transparent or has a hole through which the retinoscopist can view the patient's eye along the retinoscope's beam of light. A patch of light is formed on the patient's retina and by moving that patch in a given direction and observing the direction in which it appears to move after refraction by the patient's eye, the retinoscopist can determine whether the patient's retina is focused in front of, at, or behind the retinoscope's sight hole. If the light reflected from the patient's fundus (called the retinoscopic reflex or light reflex) and observed in the patient's pupil through the retinoscope moves in the same direction as the movement of the mirror (this is referred to as a with movement), the eye is hyperopic. If the reflex moves in the opposite direction to that of the mirror (against movement), the eye is myopic. Sometimes it is impossible to see a clear movement one way or the other but only a bipartite reflex, showing opposite movements in the two sectors of the pupils (this is called a split reflex or a scissors movement). The refractive error is determined by placing lenses of various powers in front of the patient's eye until no movement is seen, i.e. the whole pupil is either illuminated or dark and the image of the patient's retina is then conjugate with the plane of the retinoscope's sight hole. When this phenomenon occurs the neutral point has been reached. The neutral point is measured for each principal meridian of the eye if it is astigmatic. To arrive at the patient's error of refraction the dioptric power corresponding to the distance between patient and retinoscope (called the working distance) is subtracted from the total lens power used to obtain neutralization. The amount of dioptric power subtracted is called the allowance. (Fig. R13) Syn. skiascope. See retinoscopic band; chromoretinoscopy; fundus reflex; velonoskiascopy.
spot retinoscope A retinoscope that projects a circular beam of light upon the patient's retina.
streak retinoscope A retinoscope that projects into the patient's eye an oblong streak, which can be adjusted in width and rotated in various meridians. It is more efficient than the spot retinoscope in determining astigmatism.
Fig. R13 Optical principle of a retinoscope (O, observers eye; P, patients eye; M, semi-silvered mirror)enlarge picture
Fig. R13 Optical principle of a retinoscope (O, observer's eye; P, patient's eye; M, semi-silvered mirror)
References in classic literature ?
Put us on short allowance, then, doctor," responded Kennedy, "but we must not despair.
About 80,000 went in payments on all the estates to the Land Bank, about 30,000 went for the upkeep of the estate near Moscow, the town house, and the allowance to the three princesses; about 15,000 was given in pensions and the same amount for asylums; 150,000 alimony was sent to the countess; about 70,00 went for interest on debts.
After locking up the bureau again, he walked to the window and gazed out as impassibly as he had done at the beginning of the interview, while Raffles took a small allowance from the flask, screwed it up, and deposited it in his side-pocket, with provoking slowness, making a grimace at his stepson's back.
I answered dutifully that I was quite ready to obey, on the condition that he should reimburse me by a trebled allowance for what I should lose by giving up the Art of Caricature, or that Lady Malkinshaw should confer on me the appointment of physician-in-waiting on her, with a handsome salary attached.
My good opinion makes allowance for the state of my poor darling's mind, after the shock that has fallen on her," Alban answered quietly.
Making all allowance for the follies that men committed every day in their relations with women, Montbarry's delusion was still the most monstrous delusion on record.
She often pondered how she might obtain two eggs daily instead of one, and at last, to gain her purpose, determined to give the Hen a double allowance of barley.
Making due allowance for exaggeration, the description of Miserrimus Dexter on his departure from Mrs.
I have made up my mind,' said Madame Mantalini, as tokens of impatience manifested themselves in Ralph's countenance, 'to allowance him.
And what are your objections to the allowance of the honour which I have sollicited?
It is, he thinks, clearly necessary that a gentleman possessed of the average allowance of common sense, should accompany Miss Verinder to the scene of, what we will venture to call, the proposed exhibition.
to make me a handsome yearly allowance, payable quarterly, on two conditions.
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