Measuring cyclotorsion

1 August 2017 | Fiona Rowe (Prof) | EYE - Paediatrics, EYE - Strabismus

The aim of this study was to investigate if different methods of measuring cyclotorsion (synoptophore, KM screen test and single Maddox rod test) produce the same results and if these values are repeatable in adult patients. For the synoptophore, the A17a/18a slides were used (cross and segmented circule) and aligned so both were vertical and the cross within the circle. The single Maddox rod was used at 3m distance within a trial frame. The single lens was aligned vertically to produce a horizontal streak image and turned so it was perceived to be horizontal. The KM screen was at 1m distance with use of red / green glasses. Movement of the computer mouse allowed overlay of the horizontal line box over the horizontal line image. Twenty subjects were included in the study; aged 48 years (28-69) and 95% with vertical deviation. 55% were excyclo on the synotophore, 90% with single Maddox rod and 75% on KM screen at first testing. At second test, 55% were excyclo on the synotophore, 85% with single Maddox rod and 50% on KM screen. There was a significant difference between the synoptophore and single Maddox rod plus the single Maddox rod versus the KM screen. All tests were reproducible for each test-retest with high repeatability. The single Maddox rod measured larger amounts and the synopthore measured the least. The three tests are not interchangeable. However, individually they are repeatable so can be relied on for measuring torsion in the same patients over time.