W3 Sensory Fusion

what are the 3 grades of BSV

Simultaneous perception

Fusion (sensory, motor)

Stereopsis

what is sensory fusion

Integration of similar images at the cortex

images must be similar in brightness, size and form

when / who do you assess sensory fusion

px with manifest strabismus

what does testing for sensory fusion help detect

helps detect what type of strabismus it is

what are the different types of strabismus

confusion

pathological diplopia

suppression

abnormal retinal correspondence

what is confusion

overlapped images because px sees different images in each eye

what is pathological diplopia

when the px sees 2 of each image

either crossed or uncrossed depending on tropia

what is suppression

in children under age of 8. the brain will block out an image in the tropic eye and focus on the image of the fixating eye

what are the 2 types of suppression

partial

intermittent

what is partial suppression

suppression only in a part of the image in one eye

eg: only in macula / fovea

the larger the angle of suppression the larger area is suppressed

what is intermittent suppression

suppression in SOME circumstances only

eg: only in distance / in near

how would you investigate suppression

diagnose

determine size and position

measure density

how would you measure suppression with prisms

prism placed before deviated eye

prism increased until px notes diplopia

repeat fro base in, out, up and down

what do you use to measure the density of suppression

Sbisa bar

how to use the Sbisa bar to measure density of suppression

graded bar of varying density red filters

placed in front of fixing eye

px asked to view white light and asked what colour they can see

filters increase in strength

when px sees the light change from red to white, record the level before this change

what does it mean if their suppression density is less than 10

weak suppression

what is abnormal retinal correspondence

begins in children under 8

fovea of one eye learns to correspond to non-foveal area in another.

how to test for sensory fusion

total dissociation

partial dissociation

what is total dissociation

each eye will see a different target and image

what is partial dissociation

part of a target seen by both eyes

red/green filters

red = re

green = le

worth 4 dot test

management for esotropia

prescribe max plus / min minus

base out prisms

excerises

refer to HES

management for exotropia

max minus/ min plus

base in prism

excerises

refer

management for constant suppression

none

cosmetic surgery

what are bagolini lenses

Similar to maddox rod (less dissociating).

Striated plano lenses (45 and 135 degrees in alternative eyes)

Patient sees a streak from each eye (Normal = see an X)