Covers binocular single vision, how it develops from birth to around six years, and the three factors it depends on: eye alignment, clear optical media and a functioning visual cortex. It then sets out the grades of binocular vision (simultaneous perception, fusion and stereopsis) and the abnormalities of suppression, amblyopia with its clinical features, abnormal retinal correspondence and diplopia, including uniocular diplopia. The note closes with the Worth four-dot, fixation, after-image and natural density filter tests, followed by treatment of concomitant strabismus.
Topic 23 of 91 in the MU Sofia syllabus for Ophthalmology (Medicine, Year 4). The free AceMed note covers it in 5 sections, about 920 words (6 min of reading), with 16 flashcards.
In this note
Binocular single vision Topic 16
Abnormalities of binocular vision
Abnormal retinal correspondence
Uniocular diplopia
Test of binocular vision and sensory functions
Binocular single vision Topic 16
= when the eyes are fixated on the object the image is formed separately on the fovea of both eyes but they are perceived as one image
Reflex acquired during 6 months and completed during first years
At birth à no central fixation and random eye movement
First monthà fixation starts and established by 6 months
By 6 monthsà macular stereopsis & accommodation reflec is full
By 6 yearsà full visual acuity and binocular vision achieved
Factors affecting it
1. Straight eyes àprecise coordination of motor mechanism (gaze)
2. Clear vision à no opaqueness and any other hindrances (sensory mechanism)
3. Visual cortexà proper function (mental process)
Any disease affecting the above mentioned factors may lead to hindrance of binocular vision and cause a squint.
Grades of single binocular vision
a) Simultaneous perception of different objects and the joining of the two
b) Fusion à ability to superimpose two incomplete but similar images to form one
c) Stereopsisà ability to perceive third dimension ; depth
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