Lab 1 Flashcards
A concave lens is a ____ lens
Diverging
Concave/Diverging lens
Thinner in the middle and thicker at the edges.
Minifying effect (appear to make things look smaller)
Corrects myopia and is labeled with a -
A convex lens is a ___ lens
Converging
Convex/Converging
Thicker across middle and thinner at edges.
Corrects hyperion and labeled with a +
Cylindrical lens
Has variable power throughout the lens. The power varies uniformly from zero power in one meridian to the maximum dioptric power in the opposite (perpendicular) meridian. The maximum and minimum powers for a particular cylindrical lens are 90 degrees apart.
Diopter
The reciprocal of the focal length (in meters) of an optical component and is commonly used in writing ophthalmic prescriptions. Abbreviated as either D, DS (diopters of sphere) or D Cyl (diopters of cylinder).
The amount of cylinder is the
difference between the two major meridians
How to find the focal length of the lens given the lens power.
100/lens power
Ex: a +1.00 D lens focus parallel light at 100 cm. (100/+1.00= 100 cm)
A +1.50 D lens focuses light at 66.67 cm (100/+1.50)
and a +2.00 D lens focuses light at 50.00 cm. (100/+2.00)
Die in a cave.. oh my my
Diverging/concave lens… myopia minus
How to find the dioptric power of a lens given the focal length
100/focal length
100/focal length=
lens power
100/lens power=
focal length
shakometry
Hand neutralization. Either will be with or against motion and a plano lens is neutral motion.
Does a minus lens go with or against motion
With
Does a plus lens go with or against motion
Against
When can “with” motion be exhibited from a plus lens?
When the plus lens is held at an eye-to-lens distance greater than the focal length of the lens. In this case, the image is inverted.
Why does “with” or “against” motion occur
Due to prismatic displacement. The direction of motion is dependent on the position of the prism’s apex.
In a minus (concave) lens, the prisms are __ to ___
Apex to apex
In a plus (converging) lens, the prisms are __ to ___
base to base
The stronger the lens, the __ the speed of motion
Slower
The weaker the lens, the ___ the speed of motion
Faster
Lenses that are thinner in the middle and thicker on the edges
Diverging/concave/minus lenses that diverge light.
Myopes uncorrected focus light in front of retina. Diverging lenses diverge light so it focuses on the retina.
Lenses that are thicker in the middle and thinner on the edges.
Converging/convex/plus lenses that converge light.
Hyperopes uncorrected focus light behind the retina. Converging lenses converge light so it focuses on the retina.
90
The most amount of prescription is in the horizontal meridian.
emmetropia
An eye that requires no distance correction
