20.Binocular vision. Diplopia.

Question 1

normal patient have binocular vision ?

Answer 1

yes

Question 2

how do the eyes avoid double vision ?

Answer 2

brain must be able to fuse the two images in order to avoid double vision - achieved by having each eye positioned so that both fovea ae simultaneously fixating on the object of regard

brain combines the visual information from both eyes into a single imaging

Question 3

what is the test for binocular alignment ?

Answer 3

a penlight held several feet away from the patient
the patient asked to look into the light
pinpoint light reflex should appear - if the eyes in alignment

Question 4

what is esotropia?

Answer 4

if eye positions are convergent

one eye points inwards and the light reflex will appear more temporally

Question 5

what is extropia?

Answer 5

if eye positions are divergent - one eye points towards - light reflex will be located more nasally in the eye

Question 6

what is the cover test ?

Answer 6

more accurate method of verifying normal ocular alignmnet

patient asked to ease at a distant target with both eyes open

both eyes physiologically aligned - covering one eye should not affect the position or continued fixation of the other eye

Question 7

what is a negative cover test ?

Answer 7

if one eye is rapidly covered , and the uncovered eye quickly moves then the test is considered pathological - expected in patients with diplopia

Question 8

what is the aetiology of diplopia ?

Answer 8

neuological - palsy of cranial nerves - 3,4,6 or central damage of nuclei of cranial nerve
- associated clues of palsy - ptosis or pupil abnormality
compressive palsy - aneyrysm of common posterior artery

muscular disturbances - myasthenia gravis
diabetes
hypertension

mechanical obstruction of bulb movements - tumor

hyperthyroidism - graves disease

Question 9

what is monocular diplopia ?

Answer 9

affecting one eye

Question 10

what causes monocular diplopia ?

Answer 10

refractive error , lens opacity , macular disease

Question 11

what can determine if there is an abducens palsy?

Answer 11

examining the range of eye movement - converging strabismus of one eye towards the nose

Question 12

what is suggestive of myasthenia graves diplopia ?

Answer 12

variability of diplopia during episodes

, typically increasing in severity and with fatigue and increasing ptosis

Question 13

isolated oculomotor nerve palsy is due to what in patients over 50 years old ?

Answer 13

due ischemic microvascular disease

Question 14

what increases suspecian of aneurysm of common posterior artery requiring EMERGENCY CT /MRI ?

Answer 14

isolated occulomotor nerve palsy , accompanying pupillary involvement , severe pain and below the age of 50 years old

Question 15

multiple central nervus system dysfunction of palsy needs urgent what ?

Answer 15

CT/MRI

Question 16

in suspicion of myasthenia graves what additional test should be performed ?

Answer 16

tensilon test

ach receptor antibodies in blood test