BSV & Orthoptics Diagnostic tests by jasmin modi

Here we included
Worth four dot test
Hess screen
Bagolini striated glasses
Diplopia charting

1. Diagnostic tests Binocular single vision

2. Agenda WORTH FOUR DOT TEST HESS SCREEN BAGOLINI STRIATED GLASSES DIPLOPIA CHARTING

3. Worth four dot test

4. WORTH FOUR DOT TEST 1 INSTRUMENTS RED GREEN GLASSES VISION DRUM /CHART NEAR WFDT TORCH PRE REQUISTIC CRITERIA PATIENT WEARS RED GREEN GOGGLES RED IN FRONT OF RIGHT & GREEN IN FRONT OF LEFT EYE

5. INTERPRETATION PATIENT SEES ALL FOUR LIGHTS IN ABSENCE OF MANIFEST SQUINT HE/SHE HAS NORMAL BINOCULAR SINGLE VISION WITH ABNORMAL RETINAL CORRESPONDENCE PATIENT SEES ALL THE FOUR LIGHTS AS ABOVE EVEN IN THE MANIFEST SQUINT 2.IF ONLY TWO RED LIGHT SEEN ,LEFT EYE SUPPRESSION 3.IF ONLY THREE GREEN LIGHT SEEN ,RIGHT EYE SUPPRESSION 1

6. INTERPRETATION 5.IF PATIENT SEES THREE GREEN LIGHTS AND TWO RED LIGHTS ALTERNATELY ,IT INDICATES PRESENCE OF ALTERNATING SUPPRESSION 6.IF PATIENT SEES FIVE LIGHTS 2 RED & 3 GREEN PATIENT HAS DIPLOPIA 1

7. Hess screen

8. HESS SCREEN PRINCIPLE Haploscopic principle PREREQUISTIES Full understanding of test Good vision in both eyes Central fixation Normal retinal correspondence 2

9. Traditional Hess screen consisted of single tangent screen made up of black cloth 3 ft wide * 3 (0.5) ft long Marked by horizontal and vertical red lines The distance between each line subtends a visual angle of 5 degree Fixation points are indicated at the center of the screen and intersections of the 15 and 30 degree lines by red dots The red dots form an inner square of 8 dots along the 15 degree and an outer square of 16 dots along the 30 degree lines 9

10. The inner square represents the 8 cardinal directions of gaze and outer gaze cover extreme directions of gaze Indicator consists of a knot tying three green cords together to form letter ‘Y’. In the end of the central vertical green cord is fastened to a movable black rod 50 cm long 10

11. Modified Patient wears red green glasses Seats 50 cm from screen Patient sees Fixation point red light in right eye Indicator point green light in left eye The patient is asked to superimpose the indicator successively on each of the fixation points , and the relative position of the eyes plotted for each of the directions of gaze on a chart which Is replica of Hess screen 11

12. Digital Hess screen It provides clinician to computer based tool for assessing patient from paralytic strabismus using image manipulation technology and software technology Designed to run on any computer with a 19 inch display with calibration on first time usage It will help to diagnose strabismus ,data record and analyze 12

13. Operating methods Patient wears red green glasses Room lights are extinguished and red and a blue circle displayed on screen Right sees red circle and left sees the blue Patient instructed to move the blue circle using the mouse until it appears to be centered on the red circle. 13

14. As the eyes dissociated any deviation in this direction of gaze will result in a misalignment of the circles This is repeated for either 9 or 25 directions of gaze Multiple plots can be superimposed to assess longitudinal changes and the exact amplitude of any deviation can be displayed at any point on the chart 14

15. Interpretation Compression of the space between two plotted fixation points indicates Under action Expansion of the space between two plotted fixation points indicates Over action Smaller field belong to the eye with paretic muscle (figure) Non affected eye shows the larger field expressing the overaction of the contralateral synergists(figure) Fields of similar shape and size suggestive of comitant deviation ,dissimilar shows imcomitant In the smaller field the greatest displacement away from the normal cardinal direction will indicate the paretic muscle ( underaction ). In the larger field the greatest displacement away from the normal cardinal direction will indicate overacting of muscle 15

16. Bagolini striated glasses

17. Bagolini striated glasses Instruments Glass plates contains extremely fine parallel striations on the surface when looking through them a spotlight appears as a fine streak of light perpendicular to the striations . The principle is basically is the same as the Maddox rod except that the patient can see through the bagolini glasses 17

18. Procedure Test distance is 6 meters & 33 cm performed in a room with subdued light . patient is instructed to fixate at a spotlight. The striated glasses are placed in a trial frame with their axis oriented 45 and 135 respectively 18

19. A normal person would see two streaks of light forming a intersecting at the spotlight For strabismus , A patient having a constant tropia having normal retinal correspondence with no suppression will experience diplopia. Two spotlights crossing each streak centrally In the presence of suppression of one eye the patient will see the spotlight crossed by the line infront of non suppressing eye only. 19

20. Patient with harmonious anomalous retinal correspondence will see a perfect cross as seen by normal person but cover test shows tropia Two streaks but only one crossing through the center of light indicate a suppression area with either NRC or unharmonious ARC. In the presence of small angle tropia , if the patient sees a perfect cross as seen by a normal on cover test ,NRC indicated 20

21. Diplopia charting

22. Diplopia charting

23. Diplopia chart  is the record of separation of the diplopic or double images in the nine positions of gaze. It can be plotted charted in patients who cooperate and can appreciate the double vision and with incomitant or comitant deviation. 23

24. Procedure The patient should be comfortable with his head erect and should preferably be still throughout the examination. The test is preferably carried out in a dark room. Red glass is put in front of one of the eyes (red in front of right, R for R, is a convention). It is desirable to use Armstrong goggles since these are shaped to fit the orbital margin and therefore patient would be looking only through the colored medium. The examiner holds the torch (vertical source of light) at around ½ m or 1 m (It is important to mention the distance on the chart). This source of light could be horizontal if the complaint is of vertical separation of images The light is held directly in front of the patient at first. 24

25. Method Therefore, in paralysis of the left lateral rectus muscle (Fig 1), the separation of images would be maximal in the left gaze or levoversion . If the eye deviates inwards, it will project outwards the image of an object fixed by other eyes. Therefore, in the position of eyes in which the images are most widely separated, the distal image always belongs to the paralytic eye. With the help of color of the image the eye (to which the images belongs) could easily be found 25

26. If the patient sees a single image, the examiner must establish whether it is a fused image, if suppression is present or if one image is obscured, for example by the patient’s nose bridge. If there is no double vision in the primary position, the position in which double vision appears and is maximal is to be noted. If the patient notes a double image, the relative position of these images is noted. The light is now carried to the right and then to the other 8 positions of gaze. In each gaze position the patient must be asked whether the images are parallel or tilted; if the torsion is present colored pencils can be given to an observant patient to show the separation in torsion. Also, in each gaze patient should be asked the amount of separation subjectively and its increase in a particular gaze. 26

27. Interpretation The position in which diplopia appears The position in which the separation of the image is the greatest In the direction of the action of the paralyzed muscle, the double vision or the separation would be greatest because of the under action of the muscle and overaction of the antagonist muscle and yoke muscle. 27

28. Precautions 28

29. Reading on paper 29

30. Values It only gives a picture of the patient’s double vision. Maximal separation of images may give an idea about the paralyzed muscle Not very useful in recording paresis Not much helpful in diagnosis in multiple muscle pathologies 30

31. Thank you Jasmin !