SYNAPTOPHORE

SYNAPTOPHORE• also known as major amblyoscope.

• it is a haploscopic device based on the mechanical dissociation of the two eyes, by the means of two optical tubes.

• it measures the angles of deviation

• it treats binocular vision anomalies by conventional orthoptic method .

• it involves the use of after images,automaticflashing and haidinger’s brushes.

HISTORY • 19th century by E. Hering.

• 20th century C. Worth used this instrument for compensation of horizontal and vertical deviation by strabismus.

• M. Maddox defined usage of this instrument in 1931. She set 3 levels of SBV and their training.

• In Britain known as synoptophore, but in USA as troposkop.

OPTICS• 2 tubes with a right angled bend on a base with

chin and head rest.

Each tube has :

• a light source for illumination of slides

• a slide carrier at the outer end

• a reflecting mirror at right angled bend

• eye piece of + 6.5D at inner end to relax accommodation.

• These tubes can be converged,diverged,movedvertically together /seperately by knobs.

• tubes can be adjusted according to IPD of p/t.

• slide carriers can be adjusted for torsion by rotation.

• these adjustments made for horizontal ,vertical, torsional positions on each tube can b read by means of scales in degrees/prism diopters.

scales

• 0 degree inwards BO prism / convergence.

• 0 degree outwards BI prism/ divergence.

light switches

• simultaneous/alternate illumination of tubes for performing cover test.

HOW TO MEASURE DEVIATION• The horizontal angle between the optical tubes varied

by moving the handles. The angles through which the tubes are moved are recorded in degrees on the outer edge & in prism dioptres on the inner edge of the scales.

• The tubes lock together by central lock,allow vergenceexercises to be given, by slow convergence / divergence of each tube equally .The amount of vergence is recorded on the scale in degrees.

• The slide carrier can be moved upwards or downwards upto 10 prism dioptre by the controls & vertical deviations & vergences are recorded on the scales. To measure vertical deviation >10 prism dioptre, slide carriers are moved in the opposite direction by elevation & depression controls

• The elevation & depression device included in the instrument is for measuring the angle of deviation in different vertical directions of gaze.

• Torsional deviation is measured & corrected by the

rotating slide carrier around the optical axis of the

tube. Rotation of 20⁰ on either slide is obtainable.

SYNAPTOPHORE SLIDES• different pair of slide used to perform various

diagnostic & therapeutic tests.

• Based on Grades of Binocular Vision

• Simultaneous perception slide

• Fusion slides

• Stereoscopic slide

SIMULTANEOUS PERCEPTION SLIDE • 2 dissimilar slides of 2 different pictures which can

be overlapped constitute a pair of simultaneous perception slides. Each slide is presented separately to each eye.

• Graded by their size into 3 groups –

• SIMULTANEOUS FOVEAL PERCEPTION SLIDE (SFP) :

small sized pictures, which do not exceed the size of

fovea. foveal slide 1⁰

• SIMULTANEOUS MACULAR PERCEPTION (SMP) :

The pictures slightly larger than the SFP.macular

slide 1-3⁰.

• SIMULTANEOUS PARAMACULAR SLIDES (SPP):

have largest pictures & form images that extend into paramacular areas(paramacular slide1-5⁰)

FUSION SLIDES: • consists of 2 similar pictures each of which is

incomplete in one small detail.

• Grading : The fusion slides are also graded according to size in the same way as the simultaneous perception slide

IN THE PRESENCE OF SUPPRESSION EITHER OF THE POTS WILL BE MISSING IN THE RESPECTIVE EYE

STEREOSCOPIC SLIDE • 2 pictures of same object which are taken from

slightly different angles are imaged on disparate retinal areas in the 2 eyes & when the entire picture is fuses, the disparity gives rise to the perception of stereopsis of the dissimilar positions.

HAIDINGER’S BRUSH DEVICES• operated by the 2 on/off switches (29), 2 speed controls

(18) and 2 reversing switching (30) present on base unit. Iris diaphragms fitted on to the tubes helps to restrict the field of the vision and helps to stimulate the target point.

• The entoptic phenomenon of Haidinger’s brushescaused by the action of polarized light falling on themacula.

uses• treatment of eccentric fixation • abnormal retinal correspondence. • The brushes can be appreciated more easily if the blue

filters are inserted in the slots

BIELCHOWSKY AFTER IMAGE TEST • special slides for the to detect abnormal retinal

correspondence.

• Right fovea is stimulated with vertical and left with horizontal bright light.

• Pt is asked to draw the position of after images .

• A pt with NRC will draw a cross .

• An esotropic p/t with ARC will draw vertical image to the left of horizontal image to the left of horizontal

• An exotropic pt with ARC will draw vertical image to the right of horizontal image .

USES : • Diagnostic uses : -

1. Measurement of objective angle of deviation

2. Measurement of subjective angle of deviation:

3. Measurement of deviation in cardinal directions of gaze

4. Measurement of IPD

5. To detect the retinal correspondence

6. Estimation of grades of binocular vision

7. Measurement of range of fusion or version

8. Measurement of angle kappa

• Therapeutic Uses:-

1. Suppression.

2. ARC

3. Eccentric fixation

4. accomodative eso(dissociative training).

5. To improve fusional amplitude in heterophorias

& intermittent heterotropias

IPD• arms of synoptophore at 0.

• p/t looks at centre of simultaneous perception slide picture at right hand tube with R eye.

• examiner closes his R eye and aligns the reflection of light on the centre of p/ts pupil to the central white line on the mirror unit of tube

• repeat with left eye.

• read IPD from mm scale.

Measurement of objective angle of deviation

• Simultaneous perception slides are placed.

• patient asked to look at the pictures & the arm controlling the picture in front of the deviating eye is moved by examiner in opposite direction until there is no movement of the either eye on cover test performed by alternatively turning of the light.

• The reading on the horizontal scale & vertical scale in front of the deviating eye is the objective angle of deviation.

• arm of synaptophore in front of the deviating eye is at 20 ΔD BO & has to be raised 2 ΔD , the objective angle:20 ΔD eso & 2 ΔD HT

measurement of subjective angle of deviation:

• the patient is asked about the position of the pictures used.

• If the the lion in the cage then, objective= subjective angle.

• If the patient does not see the lion in the cage , ask to move the handle with cage in front of the non fixating eye until he sees two pictures superimposed. This is the subjective angle.

• By means of rapid alternate flashes, check whether or not the eyes move when the patient is asked to fixate on each picture in turn to make sure that an actual change in the angle between the visual axis has not occurred by either relaxing or increasing the accommodative effort in cases of variable angle of deviation.

• Problems

1. Small children may not cooperate.

2. Suppression may prevent superimposition of picture ,use paramacular perception slides.

3. The patient may never succeed in putting the lion in the cage & it may suddenly be seen on the opposite side of the cage. In such cases the crossing point is considered to be the subjective angle.

To detect the retinal correspondence• If the OA=SA then ,NRC .

• When the patient reports that the targets are separated with the instrument set at objective angleARC.

• OA-SA= angle of anomaly.

• harmonious if OA-SA=OA. In

• unharmonious ARC, AA<OA.

• Problems

• suppression and changes in the mode of localizations.

measurement of deviation in cardinal directions of gaze

• The tube is placed before the fixing eye in the required position of measurement & the patient adjusts the tube before the non fixing eye until he sees the lion in the cage. The angle of deviation is measured in all positions of gaze.

measurement of primary & secondary deviation

• SMP slides are placed.

• the patient is asked to fixate with the other eye & the tubes are kept at zero reading. Then the light before the fixing eye is switched off & the deviation of the other non fixing eye is noted. The tube before the non fixing eye is moved in opposite direction of fixation movement until no movement is noted.

to detect the presence & type of suppression

• SFP slides are used initially . in foveal suppression: SMP slides, in macular suppression:SPP slides are used.

• if suppression patient sees either lion or cage.

• Suppression scotoma can be mapped out at least in the horizontal meridian . One arm of the instrument is rotated & the points are noted at which the target carried by moving arm disappears & reappears.

measurement of range of fusion/version• Horizontal:

• Fusion slides in place.

• the tubes are locked at the angle at which the patient joins the pictures.

• The small screw for the adjustment of the locked angle is used to converge or diverge the tubes.

• 4 divergence:

• fusion is estimated by moving the tubes away till the fusion breaks(break point) ,slowly turned back till the fusion is regained(recovery point).

• 4 convergence :

• ask p/t to move tubes towards each other to the point at which fusion breaks & he sees 2 pics(break point).

• The arms are then moved back into a less convergent position until fusion is regained(recovery point).

• Amplitudes for near :

• measured using –3.00 DSph lens placed b4 each eye.

• Vertical :

• Fusion slides are placed

• tubes are locked at angle at which the p/t joins picture.

• move 1 pic upwards or downwards & the ability of the patient to maintain a fused picture is found out.

• The vertical fusion = synaptophore reading.

• Torsional fusional range: can also be assessed

findings to b recorded as:• DISTANCE:

• 30 Δ ET ,obj & sub.

• 1st & 2nd grade of fusion at angle

• convergence to 42 Δ BO/recovery at 32Δ BO

• Divergence to 12 ΔBO /recovery at 20Δ BO

• NEAR (with -3 DSph)

• 44Δ ET ,obj & sub.

• 1st & 2nd grade of fusion at angle

• convergence to 56 Δ BO/recovery at 44Δ BO

• No divergence past angle,suppression OD

Measurement of angle alpha• visual axis cross the cornea on the nasal side of

optic axis or the midpupillary line.The small angle between optic axis & visual axis is angle alpha.

• rarely exceeds 5⁰ to 7⁰.

• + : VA cuts the cornea on the nasal side of OA.

• - : VA cuts the cornea on temporal side of OA.

• to measure :

• a special slide with of a row of numbers & letters (4 3 2 1 0 A B C D) & animal pictures for children & illiterate placed at 1⁰ intervals kept b4 eye under observation.

• The patient is asked to focus on the 0, while the examiner looks for corneal reflex.

• The patient is asked to look either 1 letter/no: until the corneal reflex is centered.

• The degree of deviation corresponding to the letter or number is recorded.

• if R eye is tested & reflex is central when the patient looks at number 2 the patient has 2⁰ -ve angle alpha in the right eye.

THERAPEUTIC USES:-1. SUPPRESSION:

• crossing technique:

• para macular SMP slides in synaptophore.

• fix the target viewed by the dominant eye & move the target of the suppressed eye from periphery of field towards the suppression scotoma.

• disappear in suppressed area & reappears after the entire scotoma has been crossed.continue this back and forth movement of the target across the suppression area until this area until patient can simultaneously perceive both the targets & superimpose 2 images.

• macular massage

• chasing technique

2. TO IMPROVE THE FUSIONAL AMPLITUDE IN HETEROPHORIAS & INTERMITTENT HETEROTROPIAS

CONCLUSION

• It is ideal for the assessment and treatment of ocular motility disorders by reliably performing the most comprehensive binocular vision assessment available today.