Synaptophore

orthoptic instument

1. Synaptophore Manjusha lakshmi MSc.optometry

2. Synaptophore( amblyoscope ) It is an basic orthoptic instrument used for diagnostic as well as therapeutic purpose. The word synaptophore derived from greek word. Synaptophore Sin with Ops eye Phore bearing

3. History The oldest model is developed by Claud worth . Mc. Maddox first develop slides used in early device.

4. Principle Haploscopic principle it is based on the principle of division of physical space in to two separate area of visual space each of which is visible to one eye only.

5. Parts Two tubes for viewing picture Lenses with in the eyes piece are +6.5 DS Pairs of slides Controls allow vertical separation of the target as well cyclotorsional adjustment Mirror in each tube to reflect the image of target through the eye piece into corresponding eye. Scales to measure the amount of deviation Illumination system to increase or decrease the stimulus luminance

6. Slides Simultaneous perception slides Foveal Macular Para macular Peripheral Fusion slides Steropsis slides Special purpose slides After image slides Haidinger brushes Slide with number or letters

7. Simultanous perception

8. Fusion

9. Steriopsis slides

10. Special purpose slides After image slide Haidenger brushes

11. Uses of synaptophore The uses of synaptophore divided into two Diagnostic uses Therapeutic uses

12. Diagnostic uses Estimation of grade of binocular single vision Measurement of objective and subjective angle of deviation Measurement of deviation in all cardinal direction of gaze Measurement of inter pupillary distance To investigate the state of retinal correspondence Measurement of primary and secondary deviation To estimate presence and type of suppression Measurement of fusional vergance measurement of angle kappa Measurement of AC/A ratio

13. Therapeutic uses It is used in treatment off Supression ARC Amblyopia with Eccentric fixation Accomodative esotropia Heterophorias and intermittant heterophorias

14. Preliminary setting The patient’s chair and the table should be adjusted so that he is able to look through the centre of the eye-pieces comfortably with his head erect. The chin and forehead rest should be adjusted to suit the patient. The patient’s interpupillary distance (I.P.D.) must be measured and the instrument adjusted so that the distance between eye-pieces is equal to the interpupillary distance.

15. Diagnostic uses

16. Estimation of grade of binocular single vision Simultanous perception First grade of bsv Tested using two dissimilar picture such as an object and a surround E.g.: cage and lion Patient is asked to put the lion in cage by moving the arm of synaptophore Ideally the foveal picture must be used. But the target size should be appropriate to the patient visual acuity Slide size Angle subtended Foveal 1 degree Macular 1 to 3 degree Para macular 3 to 5 degree Peripheral > 5 degree

17. Recording If the patient is able to see both the pictures at a time then S.M.P. is present and recorded as S.M.P. at zero degree or at a particular angle.

18. Fusion Tested using similar but incomplete picture eg : two rabbit one lacking tail and one lacking bunch of flowers. If fusion is present one rabbit complete with tail and flower will be seen. Sensory fusion: One tube is locked and patient is asked to create a composite image and the position of sensory fusion was achieved is read off the scale. Motor fusion: Lock the Colum at their real corrected angle then to measure negative fusion adduction knob adjusted and for positive fusion abduction knob is adjusted. Then note the value when the image split into two.

19. Recording Sensory fusion: present …………degree Motor fusion: Adduction BP: RP: Abduction BP: RP:

20. Stereopsis Tested using two pictures of same object which have been taken from slightly different angle if the images are fused and is seen three diamensioly stereopsis present

21. Measurement of IPD The patient should be seated at the Synoptophore inter- pupillary distance (IPD) should be adjusted so the lines on the eyepiece line-up with the corneal reflections

22. Measurement of objective angle of deviation Patient seated in front of synaptophore and IPD should be adjusted. Smaller picture should be placed in front of RE and larger picture placed in front of LE. An alternate cover test is performed by alternatively switching off the light illuminating the slides. Then according to the directions of eye movement the tube before the non fixing eye is adjust until no movement is seen. Then the measurement is recorded from scale. If the eyes moves out to take fixation left arm moved in and vise versa This can be repeated for vertical deviations.

23. Measurement of subjective angle of deviation ’ Patient seated in front of synaptophore and IPD should be adjusted Smaller picture should be placed in front of RE and larger picture placed in front of LE Ask the patient to pull or push the handle controlling the non fixing eye’s tube until the two images are super imposed. In the presence of suppression patient fail to superimpose two images. In this case a larger target should be introduce. If the patient fail to superimpose in peripheral slide the patient has no BSV

24. Measurement of The Angle of Deviation For Near by The Synoptophore : Minus 3.00D spheres can be inserted in the lens holders situated in front of the eyepiece lenses. The patient has to exert 3.00D of accommodation in order to get a clear image of the slides In doing so , each eye exerts 3Δ of convergence for each dioptre of accommodation-in other words, 9Δ of convergence in one eye or 18Δ of convergence recording the angle of deviation, we must keep this in mind and either subtract 18Δ from or add 18Δ to the major amblyoscope readings) Eg:20 prisam bsae out the devation will be 20-18 = 2 prisam base out 20 prisam base in the deveation will be 20+18=38 base in

25. Recording SMP using macular slide Angle of deviation for distance Fixing RE Objective deviation: 0 degree Subjective deviation: 0 degree Angle of deviation for near Fixing RE Objective deviation: 0 degree Subjective deviation: 0 degree

26. Measurement of cyclodeviation with Maddox slide Maddox slides (white binding) can aid the assessment of 9 positions of gaze. Horizontal and vertical deviations are assessed in the normal way. However, with the cross before the fixing eye the examiner may rotate the torsion control until the patient is satisfied that it superimposes in the centre of the green surround and all lines should run parallel.

27. Measurement of cyclodeviation with sp slides Use SP slides and put lion in front of RE and cage in front of LE The patient is asked to look at each one in turn and asked whether cage appear level. If the cage left hand side lower than right hand side incyclophoria or tropia If the cage right hand side lower than left hand side excyclophoria or tropia Incyclophoria corrected by rotating tortional screws towards the patient excyclophoria corrected by rotating tortional screws away from the patient

28. Retinal correspondence using SP slides Measure objective and subjective angle using synaptophore Find out angle of anomaly Objective angle – subjective angle= angle of anomaly Objective angle = subjective angle Normal retinal correspondence Angle of anomaly = objective angle(subjective angle zero) Harmonious ARC Subjective angle < objective angle Unharmonious ARC

29. Recording Fixing RE Objective angle: 0 degree Subjective angle: 0 degree Angle of anomaly: zero Retinal correspondence: normal

30. Measuring AC/A ratio Gradient method is often used Measure the deviation with accommodation and without accomodation divided by change in accomodation gives AC/A ratio AC/A =∆L - ∆O /D where ∆L – deviation with addl.lens , ∆O – original deviation D – dioptric power of lens Eg ; :- ∆L - 6 ∆ eso ∆ o - 2 ∆ exo D – 2 D concave sphere AC/A =6-(-2)/2 8/2 = 4 ∆/D

31. Determination of angle kappa A special slide consist of row of number or letters used for this Ask the patient to look at zero. If the corneal reflex is on nasal side the angle is positive And if the reflex is on temporal side the angle is negative The patient is asked to turn the letter or number until the reflex is centered. The deviation correspond to letter or number is recorded.

32. To estimate type and presence of suppression The area of suppression initially mapped out by recording the angle at which the image is suppressed. By lowering the angle the illumination of fixating eye until the SMP is achieved give a rough estimation of type of suppression.

33. Position of gaze In complex ocular motility cases, all 9 cardinal positions of gaze can be subjectively measured along with unilateral ductions with repeatable, standardised conditions. The subjective measurement can be performed fixing either eye in the primary position, when the central lock is released on lateral versions and using the elevation and depression controls up to +/- 30° vertically.

34. After image test There are two slides available one with vertical slit and other with horizontal slit Then right fovea is stimulated by vertical sit for 20 sec then left fovea is stimulated by horizontal slit for 20 sec Ask the patient to draw position of after image

35. Haidinger’s Brushes Haidinger brushes correspond to macula. It is used for : To determine whether amblyopic patient fixate with fovea or not. Traing technique in amblyopia to improve fixation

36. Therapeutic uses

37. Anti suppression exercises chasing flashing Macular massage Crossing technique

38. Flashing : This can be done with an automatic flashing device or by manual control of the switches. The tubes are set at the objective angle of deviation. First one light and then the other is extinguished at interval of a few seconds. This induces alteration. The speed of alteration should be slow at first but gradually increased .

39. CHASING TECHNIQUE It is a subjective exercise using the smallest SMP slide that the pt.can superimpose The two arms of the synaptophore are loosened and the pt.is asked to hold the tube in front of the suppressed eye Examiner moves the other tube in front the fixating eye in a random position Pt. is asked to chase it and superimpose the two pictures by moving the other tube As the pt.’s performance improves , smaller pictures are used

40. MACULAR MASSAGE This exercise stimulates retina of deviated eye It is done by moving the visual target across the suppression scotoma CROSSING TECHNIQUE Target is moved in front of suppressed eye from periphery of field towards suppression scotoma Target will disappear in suppression area & reappear on the other side of scotoma The movement is continued until this area has decreased to such an extent that pt can perceive both target & can superimpose the two object

41. Fusion exercises Fusion exercises were given on major amblyoscope with the fusion slides. Fusion range could be increased by gradually converging both the tubes of major amblyoscope till the fusion breaks. Exercises were given daily or on alternate days for 10 to 15 minutes depending on the tolerance and convenience of the patients.

42. Advantages Accurate measurement is possible Tube can be move separately Large selection of suitable slides are available The patient’s eye can be seen by the orthoptist and the corneal reflections can be observed. There can be rapid interchange from objective to subjective conditions

43. Disadvantages Poor fixation Not useful in non cooprative child Only corneal reflex is noted Bulky instrument, difficult to transfer from one place to other. Though the slides are kept in optical infinity distance but still it stimulates proximal accommodation of the patient. Needs expert orthoptist to handle the instrument accurately.

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