Measurement of incomitant deviations and torsion

Question 1

Tests

Answer 1

9 positions of gaze with emphasis on PCT and synoptophore
Torsion tests-
Awaya cyclo test

Question 2

SESSION OBJECTIVES

Answer 2

Be able to measure in 9 positions of gaze
Be aware of limitations of testing
Be able to use clinical tests available for the assessment of torsion

Question 3

9 positions can be assessed in

Answer 3

PCT
Synoptophore

Question 4

PCT

Answer 4

C/sgls and perform a cover test take a measurement of the deviation in primary position.
EXO deviation base in
ESO deviation base out.
Then measure in the other 8 positions.
In elevation record with the chin down as far as possible so the eyes can elevate fully.

Question 5

Recording PCT

Answer 5

Use table record BI/O and H+ V components (if combination)- measure H first

Question 6

Measurement targets

Answer 6

Primary position using a near target, other positions use a distance target

Question 7

Synoptophore

Answer 7

On the synoptophore use the torsion slides. Measure IPD and take a torsion measurement in primary position. Then move dial in 20 degrees at a time to different positions.

Question 8

Recording synoptophore

Answer 8

Record in table
Record 3 measurements for each position; the horizontal, vertical and torsion.
Also record whether eso or exo.

Question 9

Example synoptophore

Answer 9

2 degrees horizontal exo, 2 degrees vertical exo, 0 degrees torsion

Question 10

Note on fundus photographs

Answer 10

relative positions of the fovea and the optic disc are noted whilst looking at the disc or at a photo of the disc

Question 11

Normal fovea is

Answer 11

0.3 disc diameters below the centre of the optic disc. Greater displacement seen regarded as abnormal and a cyclo deviation is present.

Question 12

Incyclotropia/ torsion

Answer 12

The fovea appears relatively high

Question 13

Excyclotropia/ torsion

Answer 13

The fovea appears relatively low

Question 14

Fovea appearance and function

Answer 14

a small depression (dark) within the neurosensory retina where visual acuity is the highest

Question 15

Macula appearance and function

Answer 15

The macula is part of the retina at the back of the eye. It is only about 5mm across, but is responsible for our central vision, most of our colour vision and the fine detail of what we see.

Question 16

Torsion tests

Answer 16

Torsionometer
Awaya cyclo
Double Maddox rod
Synoptophore (white slides)

Rarely used
Bagolini
Lees screen with linear pointer

Question 17

Synoptophore method for torsion

Answer 17

Maddox slides (bound in white) are used for measuring torsion. These consist of a pair of slides where a cross is presented to one eye & a quartered circle or ‘bun’ to the other eye.
The cross is usually presented to the deviating eye & the quartered circle presented to the fixing eye. The patient is asked to “put the cross inside the bun”.
The cross is then rotated on the synoptophore by the torsion dial until the cross is both within & straight within the bun. The cyclodeviation is measured in degrees of incyclo or excyclo torsion as read from the synoptophore dial.
In practice you would measure & correct the horizontal & vertical deviation first, then ask the patient about the torsion.

Question 18

Double Maddox rod for torsion

Answer 18

The Maddox lenses are placed vertically in a pair of trial frames.
A light (pen torch) is held at 33cm and the 6m spotlight is also used for fixation.
The patient is asked if the lines appear parallel and horizontal. If one of the lines appears tilted, the corresponding lens is rotated by the examiner until the patient reports that the lines are both horizontal and parallel with each other.
Record the amount of torsion in degrees from the trial frame scale, i.e. by how many degrees have you had to rotate the Maddox lens until the patient reports the lines are horizontal & parallel?

Question 19

Torsionometer for torsion

Answer 19

The goggles are given to the patient with red lens over the right eye, and green over the left eye.
The torsionometer is then held at 40cm from the patient. The red filter allows the green line to be seen and the green filter allows the red line to be seen.
Take care to hold torsionometer straight, in primary position & not tilted.
The patient is shown the vertical lines & asked whether the lines are parallel to one another. If one of the lines appears tilted, the line is adjusted (usually by the patient) using the small knob on the front of the torsionometer until both lines appear vertical and parallel with each other.
You then read the amount of excyclo or incyclo torsion from the scale on the back of the torsionometer. You can repeat this 3 times & record each amount if you want to be sure the measurements are consistent
Up to 25° excyclotorsion and up to 10° incyclotorsion can be measured.
Can be measured in primary position as well as eccentric positions, i.e. may be useful to repeat in downgaze.

Question 20

Awaya cyclo test for torsion

Answer 20

The patient wears reversible complimentary goggles and is presented with a series of red and green half-moons from the Awaya test book held in the frontal plane.
Through the red lens the patient sees the green half moons and through the green lens the patient sees the red half moons.
Begin by wearing the goggles with the red lens before the right eye.
There are 13 pairs of red and green half moons presented at varying angles. If the half moons appear parallel in figure 0, then no cyclo deviation is present.
If the image appears intorted, i.e. the right green half moon appears tilted anti-clockwise (narrower space at the top than the bottom), this indicates that the eye is extorted and subsequent figures in which the green moon is increasingly extorted are presented in turn until the patient reports that the half moons appear parallel to each other.
In the following figures the green half moon is tilted in steps of 1°, giving a maximum tilt of 12° for the 12th pair. The red half-moon is upright on all of the figures.
Record the amount of torsion from the test plate, i.e. the plate at which the patient reports the half-moons are parallel corresponds to the amount of torsion described.
To measure incyclotorsion the goggles are turned around such that the green lens is now in front of the right eye. The same procedure is followed.

Question 22

Lees screen with linear pointer

Answer 22

Rarely used (not available here). Each end of linear pointer is marked with ink on Lees screen (horizontal).
Degree of tilt is measured with a protractor and recorded on the chart.
The mirror reverses the image so that an intorted image is extorted by the mirror in a patient with excyclotorsion – i.e. patient is plotting what eye is doing

Question 22

Bagolini striated glass test for torsion

Answer 22

Rarely used (not available here). Method as with double Maddox rod, but is less dissociative. Glasses placed in trial frames with striations vertical and the patient sees two horizontal line images of spotlight. A vertical prism may be used to separate the images. Closer to normal seeing conditions but may still suppress.