Astigmatism and Presbyopia Flashcards
(30 cards)
It is due to a distortion of the cornea and/or lens
Astigmatism
It is also known as “short arm syndrome”
Presbyopia
when the cornea has unequal curvature on the anterior surface
Corneal Astigmatism
When the crystalline lens has an unequal curvature on the surface or in its layers
Lenticular Astigmatism
The sum of corneal astigmatism and residual astigmatism
Total Astigmatism
Give 1 Residual Astigmatism
Posterior Corneal Surface
It is when the two principal meridians are perpendicular to each other
Regular Astigmatism
When the greatest refractive power is within 030 of the oblique meridians
Oblique Astigmatism
When the two principal meridians are not perpendicular to each other
Irregular Astigmatism
The sum of the two axes of the two eyes equals approximately 180
Symmetrical Astigmatism
The sum of the two axes of the two eyes does not equal approximately to 180
Asymmetrical Astigmatism
The first accurate description of astigmatism is credited to
Thomas Young
He was the first one to produce a distance test charts for astigmatism
John Green
Give 1 example of test chart for Astigmatism
Fan Dial
Give 1 example of test chart for Astigmatism
Clock Dial
When both principal meridians are focused in front of the retina
Compound Myopic Astigmatism
It is one the theories of Presbyopia where it is lens based
H-H-G Theory
It is a condition which can still be overcome by a hard or forced ciliary effort
Facultative Presbyopia
It is the earliest stage at which symptoms or clinical findings document the near vision effects of the condition
Incipient Presbyopia
Give 1 causes of sclerosis
Nutritional changes
Give 1 causes of sclerosis
Action to UV rays
Give at least 1 symptoms of Presbyopia
Occipital headache
Give at least 1 symptoms of Presbyopia
Diplopia
Give at least 1 determination of proper add
Amplitude of Accommodation
