Unit 4 Optical Appliances Flashcards
Identify five possible errors in a prescription
Out of date prescription
a prescription larger than four with no BVD
an optometrist, name or signature Missing
one eye is a plus cylinder and one eye is a minus cylinder
prism BU in both eyes.
Define Aniseikonia
Significant difference in the perceived size of images
Define anisometropia
Significant difference in refractive error between the meridians in both eyes of more than one dioptre
How many types of anisometropia are there and defined them?
Simple: one eyes affected with the other, having no prescription and effective eye can be either hyperopic or myopic.
Composite: both eyes have refractive error, but the difference is larger than two dioptres, which makes one eye, see a blurry image.
Mixed: both eyes have a refractive error, but one eyes hyperopic, and the other is myopic
Define simple anisometropia
One eyes affected whilst the other eye has no refractive error. The effected eye is either myopic or hyperopic.
Define composite anisometropia
Both eyes have a refractive error. However, the difference between them is over two dioptres, which causes one eye to see a blurry image.
Define a mixed anisometropia
Both eyes have a refractive error, but one eye myopic, whilst the other is hyperopic
What are the symptoms of an uncorrected anisometropia
Amblyopia
Strobus were patient. Patient cannot align both eyes
Diplopia.
What is the formula for working out prism power?
P= cF
P= prism power
c= decentration in centimetres
F= focal power in D
What can anisometropia induce?
Prismatic effect
Who might complain of double vision, and why
Contact lens wearers and monocular pseudophakic patients, when they’re viewing things up close because of the amount of induced differential prism when they’re looking down below the optical centre
