Anisometropia Aniseikonia

Question 1

what are the different types of aniseikonia

Answer 1

1. symmetrical: img seen by one eye is symmetrically larger in all meridians
2. meridional: size diff is mainly in one meridian (horizontal, vert, oblique)
3. asymmetrical: progressive increase or decerase in img size across the visual field
   -can be cuased by lenses: minus lens > barrel distortion
   and plus lens > pincushion distortion

Question 2

what is the rule of thumb in estimating the aniseikonia amount

Answer 2

rule of thumb is that there is about 1% magnification chnage per diopter of power difference in prescription of the 2 eyes

Question 3

what are 2 methods to measure anisikonia

Answer 3

1. space eikonomoter

2. direct comparison tests

Question 4

what are the types of aniseikonia by origin?

Answer 4

1. induced optical: cuased by a diff in correcting lens power of the 2 eyes or by corneal refractive surgery or cataract surgery
2. inherenet optical: cuased by a diff in the optics of the 2 eyes, such as refractive aniso
3. anatomic or neural : cuased by diff in the reintal structure of the 2 eyes, such as unequal cone distr
   - can occur w/ pathology

Question 5

what is a space eikonometer

Answer 5

a clinical device developed in the first half of the 20th century; the gold standard for meauring aniseikonia

Question 6

what is the standard eikonometer

Answer 6

presents different images to the 2 eyes by polarized filters-subject can adjust size of one img

• size adjustment is a measure of the aniseikonia
• direct comparison test