Purchase this article with an account.
A. V. Cruz, A. Messias, L. O. Costa, D. M. Garcia; Relationship Between the Amplitude of Lid Saccades and Blinking Dynamics in Graves Upper Eyelid Retraction. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5052.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine the influence of the amplitude of upper eyelid saccades on the rate and dynamics of spontaneous blinking in patients with Graves' upper eyelid retraction.
A magnetic search coil technique was used to register spontaneous blinks during a 5 minute period of video observation and upper eyelid saccades of 9 Graves patients (age: 22 - 62 years - 13 eyelids). Overall, a total of 873 blinks and 65 down and upward lid saccades in the lower hemifield were recorded. Signal digitalization was done at a 200 Hz sampling rate (12 bits). For blinking analysis, patients were assigned to two groups: Group 1 (G1) performed saccades with amplitudes above the median of the saccade amplitude distribution, and Group 2 (G2) performed saccades with amplitudes below the overall median saccade amplitude.
The down phase of the blinks showed striking differences between groups. The mean blinking amplitude was significantly reduced in G1 (15.7 ± 0.46 sd degrees) compared to the amplitude of G2 (30.5 ± 0.53 sd degrees, t= .21.12, p<0.0001). When the blink amplitudes were normalized by the resting position of the eyelid relative to the pupil center, the lids of G1 showed significantly smaller ratios (mean G1 = 0.55 ± 0.015; mean G2 = 1.0 ±0.017; t= 19.12; p <0.0001). Moreover, 78% of the total blinks performed by the lids of G1 had amplitudes large enough to reach the pupil center, while in G2 this figure dropped to 22% (Chi square= 123.2; p<0.0001). The median slope of the linear relationship between amplitude and maximal velocity was also reduced in G2. (G1 = 25.0; G2 = 18.1 s-1; Mann-Whitney test = 5.0, p=0.0221,). The median blinking rate and the blink up-phase did not differ between groups.
Patients with Graves upper eyelid retraction who display small saccade amplitudes will also have deficient spontaneous blink amplitudes and slower movements. These results suggest that the down phase of the blinks is dependent on the intrinsic elastic eyelid properties and can be predict by measuring the downward saccade amplitude.
This PDF is available to Subscribers Only