Binocular Single Vision Tests

Binocular Single Vision Tests

1. Binocular Single Vision tests BY: RABIA AMMER BSC.(OPTOM), M.PHIL. OPTOM) GOLD MEDALIST

2. Binocular Single Vision   Defined as: “ the state of simultaneous vision, which is achieved by the coordinated use of both eyes, so that separate and slightly dissimilar images arising in each eye are appreciated as a single image by the process of fusion.”

3. Grades of Binocular Single Vision Grade I:   Simultaneous perception   is the most elementary type of binocularity. SP is not the same as superimposition, whereby the two different pictures are seen simultaneously in the same direction. Grade II:  It represents  true fusion . Fusion is defined as the unification of visual excitations from the corresponding retinal images into a single visual percept. Grade III:  Stereopsis is the ability to fuse images that stimulate horizontally disparate retinal elements within Panum’s fusional area resulting in binocular appreciation of visual object in depth i.e. in the third dimension.

4. Retinal Correspondence Retinal elements of the two eyes that share a common subjective visual direction are called corresponding retinal points. All other retinal elements are non-corresponding or disparate with respect to a given retinal element in the fellow eye for a particular visual direction.

5. Types: Normal Retinal Correspondence: Retinal correspondence is called normal when both the fovea have a common visual direction and the retinal elements nasal to the fovea in one eye corresponds to the retinal elements temporal to the fovea in the other eye. Abnormal Retinal Correspondence: Retinal correspondence is abnormal when the fovea of one eye has a common visual direction with an extrafoveal area in the other eye. This is generally seen if the angle of squint is small and the extrafoveal point is close to the fovea. It is an attempt to regain the binocular advantage.

6. Diplopia and confusion Diplopia : when non-corresponding retinal areas are stimulated by similar stimuli. One object is seen at two different locations in the field. Confusion: when corresponding retinal areas are stimulated by dissimilar stimuli. Two different objects are seen at one location in the field.

7. Suppression It is a neuro -physiological active inhibitory mechanism in which image of one eye is temporarily inhibited or suppressed to prevent confusion or diplopia . Suppression is foveal in order to tackle confusion and extrafoveal in order to avoid diplopia .

8. Investigations for Binocular Vision All the BSV tests are aimed at assessing the presence or absence of: Normal or abnormal retinal correspondence Suppression Simultaneous perception Fusion Stereopsis Before any test is undertaken it is essential to assess the: visual acuity fixation in the squinting eye direction and size of deviation

9. Test for Retinal Correspondence Bagolini's striated glasses test Worth's 4 dot test After image test Red filter test

10. Test for Suppression Bagolini’s striated glasses Worth's four dot test 4 ∆ prism base out test Red filter test

11. Tests for Fusion:  Worth’s 4-dot test Bagolini’s striated glasses

12. Tests for Stereopsis Qualitative tests for Stereopsis : Lang’s 2 pencil test Synaptophore Quantitative tests for Stereopsis : Random dot test TNO Test Lang’s stereo test

13. Tests for stereopsis Titmus Red-green spectacles TNO random dot test ‘Hidden’ shapes seen Polaroid spectacles Figures seen in 3-D Lang No spectacles Frisby ‘Hidden’ circle seen No spectacles Shapes seen

14. This is a dissociation test which can be used with both distance and near fixation, and differentiates between BSV, or ARC and suppression . Results can only be interpreted if the presence or absence of a manifest squint is known at time of testing. Procedure: The patient wears a green lens in front of the left eye And a red lens in front of the right eye The patient then views a box with four lights ; one red , two green and one white . WORTH FOUR-DOT TEST:

15. If BSV is present all four lights are seen. If all four lights are seen in the presence of a manifest deviation, harmonious ARC is present. If two red lights are seen , left suppression is present . If three green lights are seen , right suppression is present. If two red and three green lights are seen , diplopia is present. If the green and red lights alternate , alternating suppression is present. Results

16. Orthophoria (NRC &ARC)

17. Left Eye Suppression

18. Right Eye Suppression

19. Diplopia

20. Right Esodeviation

21. Left Exodeviation

22. Left Hyperdeviation

23. Right Hyperdeviation

24. This is a test for detecting BSV , ARC or suppression . Each lens have fine striations which convert a point source of light into a line, as with the Maddox rod . Procedure: The two lenses are placed at 45°and 135° in front of each eye and the patient fixates a small light source . Each eye perceives an oblique line of light , perpendicular to that perceived by the fellow eye. Dissimilar images are thus presented to each eye under binocular viewing conditions . BAGOLINI STRIATED GLASSES

25. If the two streaks intersect at their centers in the form of an oblique cross ( an X ) , the patient has BSV if the eyes are straight , or harmonious ARC in the presence of manifest strabismus . If the two lines are seen but they do not form a cross , diplopia is present . If only one streak is seen , there is no simultaneous perception and suppression is present . If a small gap is seen in one of the streaks , a central suppression scotoma ( as found in microtropia ) is present . Results:

26. Exotropia NRC Esotropia with NRC Normal BSV Suppression of one single line central scotoma

27. Tests for sensory anomalies Worth four-dot test a - Prior to use of glasses b - Normal or ARC c - Left suppression Bagolini striated glasses a - Normal or ARC b- Diplopia c - Suppression d - Right suppression e - Diplopia d - Small suppression scotoma

28. After image test This test is performed on S ynoptophore RE is stimulated with an illuminated vertical line for 10 - 15 sec. & the patient is asked to see at its center Then the LE is stimulated with an illuminated horizontal line for 10 - 15 sec. The patient is asked to close his eyes & open the eyes after a few sec. then look at the wall.

29. Results: In NRC the patient will see the perfect cross In ARC with ET he will see the horizontal line in front of RE & vertical line in front of LE ARC with XT he will see the vertical line in front of RE & horizontal line in front of LE

30. 4 Prism base out test This test has been used to confirm the presence of a Monofixation syndrome. Procedure: The patient fixate a small light. A 4 PD base out is placed in front of one eye. In normal patients this test shows two movements. First version movement and second fusional convergence movement Results: When prism is placed in front of dominant eye then both eyes show version movement but no convergence movement in the fellow eye. When the prism is introduced in front of non dominant eye there is no movement in both eyes.

31. Red Filter Test This test is applied to reveal diplopia . Procedure: The red glass is placed in front of patient’s one eye & a light is projected to the eyes of the patient. He/ she is asked to see at the light source. Results: In case of orthophoria he will see a single red light. In case of Esotropia he will see 1 red & 1yellow light. Diplopia will be uncrossed. In case of Exotropia he will see 1 red & 1 yellow light. Diplopia will be crossed.

32. Thank you…