Abstract
Introduction: :
Background: Eyelid lid retraction in thyroid eye disease (TED) is due to a combination of increased sympathetic activity in Mullers’ muscle, fibrotic contraction of the upper lid retractors and compensatory over action due to contraction of the inferior rectus. There has been little reported on the characteristics of Levator Function (LF) in these patients and it was hypothesized that there would be a difference in the distribution of LF in this group.
Purpose: :
To use the 2 phase assessment of LF in TED patients to test the hypothesis that the primary phase of LF will be higher and the secondary phase of LF, lower, in TED patients than in a normal population.
Methods: :
LF was measured by the two phase approach (phase 1: down gaze to primary position; phase 2: primary position to up gaze) in a group of 21 normal patients and in a consecutive series of 13 patients attending clinic with TED. Measurements were taken in the standard way and other parameters were also recorded.
Results: :
A total of 13 TED patients were recruited( 11 females and 2 males with a median age of 46.0yrs (InterQuartile range 43.5 to 64.0)). Both phase 1 and phase 2 of LF were compared to results from 21 normal subjects. No significant difference seen between each phase of LF in the TED group and the control group (phase 1 mean 9.9 vs 10.1, p =0.69; phase 2 mean 5.9 vs 5.1, p =0.24). However, the measurements for the TED group were significantly more variable compared to the control group (phase 1 standard deviation 2.68 vs 0.70, f <0.001; phase 2 standard deviation 3.25 vs 0.73, f <0.001).
Conclusions: :
Whilst no significant difference between the 2 phases of LF in controls and patients was demonstrated, the variance in the measurements of the TED group compared to the controls was significantly different. We suggest that this highlights the instability of lid position due to sympathetic over-activity. 2 phase assessment offers a more detailed insight into the relative components of LF in this group of patients. This small study disproves our initial hypothesis but we plan to study a larger group of patients with TED and to subdivide this population into more finely defined subgroups.
Keywords: eyelid • eye movements: recording techniques • anatomy