Effect of head tilt on repeatability of optic nerve head parameters using Cirrus spectral-domain optical coherence tomography

AIMTo assess the repeatability of measuring optic nerve head (ONH) parameters using the Cirrus optical coherence tomography (OCT), as well as to assess the effect of head tilt on these measurements.METHODSThirty healthy participants with no evidence of glaucoma were recruited for the study. Visual acuity, intraocular pressure, standard automated perimetry and ocular examination were performed for each participant. One eye was then randomly selected and scanned undilated with the Cirrus OCT in 3 positions (neutral, 30° right tilt and 30° left tilt).RESULTSData collected from 29 eyes were used for analysis. One patient was omitted due to poor scan quality. The repeatability of the ONH parameters was analyzed using analysis of variance, coefficient of variation (COV) and intraclass correlation coefficient (ICC). Analysis of variance showed no statistically significant difference between 3 scans in a single position. There was good agreement between measurements (ICC 0.919-0.996, COV 1.94%-5.48%). Even with the presence of head tilt, repeated scans in the 3 positions showed good agreement as well (ICC 0.888-0.996, COV 2.04%-5.39%).CONCLUSIONSerial measurements of ONH parameters using the Cirrus OCT are found to have good repeatability. The ONH parameters with Cirrus OCT also maintain good repeatability despite head tilt.

Development and Clinical Application of Shapeable Head Braking Device

Objecfive:To evaluate the application effect of a plastic head brake device after radical resection of oral malignant tumors and flap repair for defects.Methods:2018-2019 years,5 months Sun Yat-sen Memorial patients oral and maxillofacial surgery for oral malignant tumor resection surgery period skin flaps hospital 150 patients randomly divided into groups.Test groups 70 examples and the control group of 80 cases,two different head braking methods were used.The experimental group used a self-designed head brake device,which was prepared to suit the height of the patient before operation.lt was used from 0 to 3 days after operation.After the operation,the head lateral range was adjusted according to the braking requirements,and the pillow height was adjusted.The control group wrapped a 500g salt bag with a treatment towel on both sides of the patient's head for head braking.The incidence of flap vascular crisis,head and neck deviation,head occipital pressure ulcer incidence and patient comfort during braking were evaluated in both groups.ResuIts:The occurrence of vascular crisis in patients with oral tumors was significantly corelated with the patient's gender,alcoholism,and head movement(P0.05),and the movement of patients'head and neck was also significantly correlated with the occurrence of vascular crisis.Compared with the control group,the experimental group had sigmificant differences in head and neck deviation,incidence of vascular crisis,incidence of head ulcer pressure ulcers and patient comfort(P<0.05).Conclusion:The degree of head movement and incidence of vascular crisis in patients Closely related.Mouldable head brake device has more than ordinary salt bag ProA better head and neck braking effect can significantly reduce the incidence of postoperative vascular crisis,improve patient comfort,and have a better clinical application effect.In addition,this device can also be used repeatedly,reducing economic costs and better improving the satisfaction of doctors,nurses and patients.

A transverse local feedback linearization approach to human head movement control

In the mid-nineteenth century, Donders had proposed that for every human head rotating away from the primary pointing direction, the rotational vectors in the direction of the corresponding axes of rotation, is restricted to lie on a surface. Donders＇ intuition was that under such a restriction, the head orientation would be a function of its pointing direction. In this paper, we revisit Donders＇ Law and show that indeed the proposed intuition is true for a restricted class of head-orientations satisfying a class of quadratic Donders＇ surfaces, if the head points to a suitable neighborhood of the frontal pointing direction. Moreover, on a suitably chosen subspace of the 3D rotation group SO（3）, we describe a head movement dynamical system with input control signals that are the three external torques on the head provided by muscles. Three output signals are also suitably chosen as follows. Two of the output signals are coordinates of the frontal pointing direction. The third signal measures deviation of the state vector from the Donders＇ surface. We claim that the square system is locally feedback linearizable on the subspace chosen, and the linear dynamics is decomposed into parts, transverse and tangential to the Donders＇ surface. We demonstrate our approach by synthesizing a tracking and path-following controller. Additionally, for different choices of the Donders＇ surface parameters, head gaits are visualized by simulating different movement patterns of the head-top vector, as the head-pointing vector rotates around a circle.