Astigmatism and Presbyopia Flashcards
A theory in which, the reduced amplitude is due to progressive weakening of the ciliary muscle
Donder’s-Duane-Fincham
Another term for Presbyopia
Short arm syndrome
What are the causes of sclerosis
Nutritional changes, UV rays, infrared radiation
What instrument is used in measuring the amplitude of accommodation
RAF Rule
How to determine the proper add?
Amplitude of accommodation, near chart va and cross cylinder technique
_________ + _________ = Total Astigmatism
Corneal and residual
What are the 2 etiologies of astigmatism?
Corneal Astigmatism and Lenticular Astigmatism
What are the charts used for Astigmatism?
Clock Dial and Fan Dial
It is where the two principal meridians are perpendicular to each other
Regular Astigmatism
What are the 2 types of Symmetric Astigmatism?
Homologous and Heterologous
What are the 2 types of Asymmetric Astigmatism?
Homonymous and Heteronymous
What type of contact lens is used in Astigmatism?
Toric Astigmatism
What type of lens is used in Astigmatism?
Cylinder lenses
What are the residuals in total astigmatism?
Posterior cornea, lens and zonule
Who is the first one to accurately describe astigmatism?
Thomas Young
In minus cylinder lens, with-the-rule lies at what meridian?
1-30 and 150-180 degrees or horizontal meridian
In minus cylinder lens, against-the-rule lies at what meridian?
60-120 degrees or vertical meridian
It is where two principal meridians are not perpendicular to each other
Irregular Astigmatism
A condition where there is an unequal curvature of the cornea
Astigmatism
What are the clinical test performed in astigmatism?
Visual acuity test, autorefraction, keratometry, retinoscopy, and monocular subjective refraction
It is when the cornea has unequal curvature on the anterior surface
Corneal Astigmatism
Is a type of astigmatism when both principal meridians are focused behind the retina
Compound Astigmatism
_______ is when parallel rays of light enter the eye and do not come to a single point focus on or near the retina
Astigmatism
______________ means eye strain
Asthenopia
________________ means old
Presbys
____________ means eye
Ops
A condition which you can still be overcome by a hard or forced ciliary effort
Facultative Presbyopia
____________ is a lens based theory in presbyopia
HHG Theory
_______ is the inability of the human eye to focus on objects up close that results with aging
Presbyopia
What does LTK mean?
Laser thermal keratoplasty
