Prism and Characteristics of Ophthalmic Lenses Flashcards
When light strikes a prism, the light ray is bent toward the ___ and the image is displaced towards the ___
The ray is bent towards the base, and the image is displaced towards the apex, or top, of the prism
How far will two prism diopters deviate light at 1 M?
2 cm
When light passes from a medium of lesser density to a medium of greater density, the path of the light is bent towards the ___
normal
Some characteristics of plus lenses include:
Magnifies images, converges images, power weakens as vertex shortens
Some characteristics of minus lenses include
Minifies images, diverges images, power strengthens as vertex shortens
What lens produces WITH motion?
minus
What lens produces AGAINST motion?
plus
Compound Lenses (sphero-cylinder lenses) combine a spherical surface with a:
Toric/cylindrical surface
The principles meridians on a compound lens are how many degrees apart?
90 degrees
Where is the cylinder generated on a plus lens?
On the front surface
Where is the cylinder generated on a minus lens?
On the back surface
Where would the full cylinder power be on this rx? -1.00 -1.50 x45
135 degrees
Where would the full cylinder power be on this rx? -1.00 -1.50 x90
180 degrees
Where would the thickest edge be on this rx? -1.00 -1.50 x135
45 degrees
Where would the thickest edge be on this rx? -1.00 -1.50 x180
90 degrees
