Astigmatism and Presbyopia Flashcards
It is the inability of the human eye to focus on objects up close that results with aging.
Presbyopia
A theory in presbyopia in which the amount of ciliary muscle contraction needed to produce a unit change in accommodation progressively increases with age.
DDF Theory (Donder’s-Duane-Fincham Theory)
It is the earliest stage in presbyopia at which symptoms or clinical findings document the near vision effects of the condition a.k.a. borderline, beginning, early, or pre-presbyopia.
Incipient Presbyopia
____________ is the condition of presbyopia in which virtually no accommodative ability remains.
Absolute presbyopia
adult patients eventually report visual difficulties when faced with gradually declining accommodative amplitude and near task demands.
Functional Presbyopia
Presbyopia is also known as __________.
short arm syndrome
A condition in presbyopia in which near vision difficulties result from an apparent decrease in the AA in dim light.
Nocturnal Presbyopia
In _________ presbyopia, accommodative ability becomes insufficient for the patient’s usual near vision tasks at an earlier age than expected.
Premature Presbyopia
________________ is the maximum increase in optical power that an eye can achieve in adjusting its focus from as far as possible (beyond infinity for a longsighted eye) to the nearest possible.
Amplitude of accommodation
It correct one eye for near and one eye for far and eliminates the need for bifocals or reading glasses, but can interfere with depth perception.
Monovision
A condition in presbyopia in which can still be overcome by a hard or forced ciliary effort.
Facultative Presbyopia
A theory in presbyopia that attributes all of the loss in accommodation to bio-mechanical changes in the lens capsule & lens and none to the ciliary muscle
HHG Theory (Helmholtz-Hess-Gullstrand Theory)
A small scale snellen’s chart used for presbyopia where the patient should hold the chart at approximately 40 cm (16 inches). This will determine the px’s near grade.
Near chart VA
The first accurate description of astigmatism as such is credited to _______ in 1800.
Thomas Young
______________ is a common form of astigmatism that causes the cornea to be oblong shaped with high refractive power in the vertical meridian.
With-the-rule astigmatism
A type of astigmatism where the crystalline lens has an unequal curvature on the surface or in its layers.
Lenticular Astigmatism
_________ was the first one to produce a distance test charts for Astigmatism.
John Green
The sum resultant astigmatism of all factors of the refractive system, due to normal variations in the surfaces of the different media
Total Astigmatism
In which the cornea exhibits a variation of curvature throughout different meridians.
Corneal Astigmatism
The meridian of greatest curvature lies between the 30th to 60th or the 120th to 150th meridian.
Oblique
The total of the degrees representing the two weakest (or two strongest) meridians for both eyes equals 180°
Symmetric
Both eyes are with-the-rule or both are against-the-rule
Homonymous
One eye is with-the-rule and the other is against-the-rule
Heteronymous
With the accommodation completely relaxed, the posterior principal of foci of both meridians would tend to fall beyond the retina
Compound Hyperopic Astigmatism
