Why Two Eyes? Know

Question 1

3 overall reasons why two eyes are better than one?

Answer 1

Spare eye
Larger visual field
Beter visual sensitivity (binocular summation)

Question 2

Hirschberg test

Answer 2

Reflexes should be decentered slightly nasally from center of the pupil for ortho.

Question 3

A detached retina is a separation between the

Answer 3

PR and RPE layers. Neural sensory retina from RPE.

Question 4

Phthisis bulbs

Answer 4

A shrunken, non functional eye.

Question 5

Take home points about having spare eyes

Answer 5

Beneficial when there is a loss of one through disease/injury.

Previously amblyopic eye can undergo improved vision when the non-amblyopic eye is severely injured or lost.

Question 6

Field of view degrees:

1. Left eye
2. Right eye
3. Binocular VF (both eyes field overlaps)
4. Total VF

Answer 6

1. 160
2. 160
3. 120
4. 200

Question 7

Vertical field of view
Superior
Inferior

Answer 7

Superior: 60
Inferior: 75
135 degrees total vertically monocularly, binocularly, and total.

Question 8

Binocular summation

Answer 8

The enhancement of visual function/performance achieved when simultaneously viewing with 2 eyes over the performance obtained when viewing with 1 eye.

However
Vision with both eyes open is not twice as good as with either eye separated. OU usually a lil better, but not 2x

Question 9

X-ray vision (controversial theory)

Answer 9

Thought of why humans developed/evolved to have two eyes on the front of head. 3D helps us see through leaves on trees. Survival. Fills in gaps where leaves are,

Question 10

Problems with more than one eye

Answer 10

Extra expenses
Eye exams take twice as long
Eyes must be aligned to yield a single perception.
Need to coordinate 12 muscles
Brain has to put together 2 pictures to get true (veridical) perception of one world. Sensory fusion
More complex neural machinery
Difference in image mag due to refractive error (anisometropia) causes aniseikonic.
Failure to fuse causes suppression, rivalry, diplopia, amblyopia.

Question 11

Laterally placed eyes is great for who? What are the pros/cons

Answer 11

Prey - gives them panoramic vision. Little of no stereo because no overlap. hard to estimate distance

Question 12

Frontal placed eyes is great for who? What are the pros/cons

Answer 12

Hunters. Gives cues about relative distance and have stereo due to overlapping fields. However, visual field degree is limited.