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Neuro-Ophthalmology - part 3

Các tính năng chính của thiết bị ghi âm chuyển động mắt đã đề cập trong chương này được tóm tắt trong bảng 1. Kể từ khi EOG vẫn là phương pháp duy nhất cho phép đo chuyển động của mắt trong khi đôi mắt là đóng cửa | The main features of the eye movement recording devices mentioned in this chapter are summarized in table 1. Since the EOG is still the only method that allows measurement of eye movements while the eyes are closed it remains important for specialized applications that require this possibility. Modern VOG systems can measure 2-D gaze direction at spatial resolutions comparable to those of search coil systems. The accuracy of VOG devices is also comparable to that of the search coil but it depends on the ability of the subjects to fixate accurately. System noise and accuracy of ocular torsion is slightly better in search coil systems than in VOG. The main disadvantage of the i ai c h oll is that it is invasive compared with the EOG IRD or VOG. Therefore search coil measurements are advisable only for relatively short recordings requiring high temporal resolution high accuracy and an objective calibration. For most other applications VOG seems to provide a good alternative to the search coil technique. Until recently the IRD was still a reasonable noninvasive alternative to the search coil at least for measuring horizontal 1-D eye movements. In the meantimes the temporal resolution of VOG improved and is now sufficient to cover the temporal bandwidth of physiological eye movements. The robustness of the system linearity with respect to displacements between the device and the eye is much better in VOG than in the IRD. Therefore the IRD appears to have been outdated by VOG. References 1 Wade NJ Tatler BW Heller D Dodge-ing I lie issue Dodge- s .a-ivalls Heiings and lhe measuremenl of saccades in eye-movement research. Perception 2003 32 793-804. 2 Wade NJ Tatler BW The Moving Tablet of the Eye The Origins of Modern Eye Movement Research. Oxford Oxford University Press 2005. 3 Porterfield W An essay concerning the motions of our eyes. I. Of their external motions. Edinburgh Med Essays Obs 1737 3 160-263. 4 Wells WC An Essay Upon Single Vision with Two Eyes Together .