Astigmatism and Presbyopia Flashcards
When the cornea has unequal curvature on the anterior surface.
Corneal Astigmatism
When one of the principal meridians is focused behind the retina and the other is focused on the retina (with accommodation relaxed).
Simple Hyperopic Astigmatism
A condition which can still be overcome by a hard or forced ciliary effort.
Facultative Presbyopia
Attributes all of the loss in accommodation to biomechanical changes in the lens capsule and lens and none to ciliary muscle.
H-H-G Theory
Defined as refractive condition in which variation of power exists in different meridians of the eye.
Astigmatism
In which either of the two principal axis are not at right angles to each other or the curvature of any meridian is not uniform.
Irregular Astigmatism
The first accurate description of astigmatism is credited to _____ in 1800s.
Thomas Young
The earliest stage at which symptoms or clinical findings document the near vision effects of the condition.
Incipient Presbyopia
A small scale Snellen’s chart and this will determine the Px’s near grade.
Near Chart VA
Eliminates the need for bifocals or reading glasses, but can interfere with depth perception.
Monovision
The inability of the human eye to focus on objects up close that results with aging.
Presbyopia
The condition in which near vision difficulties result from an apparent decrease in the AA in dim light.
Nocturnal Presbyopia
In which two principal meridians exist at right angles to each other, one of the greatest and one of the least curvature.
Regular Astigmatism
When both principal meridians are focused in front of the retina (with accommodation relaxed).
Compound Myopic Astigmatism
The sum of the two axes of the two eyes does not equal approx. 180.
Asymmetrical Astigmatism
When one of the principal meridians is focused on the retina and the other is not focused on the retina (with accommodation relaxed.
Simple Astigmatism
When the crystalline lens has an unequal curvature on the surface or in its layer.
Lenticular Astigmatism
The most common type of astigmatism based on the orientation of meridians.
With-The-Rule (WTR) Astigmatism
The condition in which virtually no accommodative ability remains.
Absolute Presbyopia
Presbyopia is also known as _______.
Short arm Syndrome
The amount of ciliary muscle contraction needed to produce a unit change in accommodation progressively increases with age.
D-D-F theory
Adult patients eventually report visual difficulties when faced with gradually declining accommodative amplitude and near task demands.
Functional Presbyopia
When both principal meridians are focused either in front or behind the retina (with accommodation relaxed).
Compound Astigmatism
When one of the principal meridians is focused in front of the retina and the other is focused on the retina (with accommodation relaxed).
Simple Myopic Astigmatism
When one of the principal meridians is focused in front of the retina and the other is focused behind the retina (with accommodation relaxed).
Mixed Astigmatism
Both eyed are WTR astigmatism and the sum of the two axes equal approx. 180.
Symmetrical Astigmatism
The principal meridians are the meridians of greatest and least refracting powers.
Astigmatism
When both principal meridians are focused behind the retina (with accommodation relaxed).
Compound Hyperopic Astigmatism
When the greatest refractive power is within 030 of the oblique meridians.
Oblique Astigmatism
Progressive age-related loss of accommodation.
Presbyopia
