[The effect of illumination on involuntary eye saccades]

A study was made of the influence of sudden illumination micromovements of the eyes. Sudden contour illumination of the eye by a 15 degrees field with a crossing in the centre and a brightness of 100 nit reduced the amplitude of involuntary saccades and their frequency. The effect was particularly distinct with preliminary recording of the eye micromovement in complete darkness without a fixation point. In the case of fixation of a stationary point with one eye and of illumination of the other, the effect was also manifest, but it was less pronounced. During illumination of the eye with diffused light (through spectacles with frosted glasses) the effect of diminution of the saccade amplitude was smaller, though the brightness remained unchanged. A decrease in the saccade amplitude was practically not observed when the point was fixed at diffuse illumination. It has also been shown that with greater brightness of the fixation point (0.3; 25; 92 and 1000 nit), the amplitude and frequency of involuntary saccades diminish. The results attest that in choosing the conditions of work of the saccadic system two factors should be taken into consideration: the presence of the contours of the visible object and its brightness, the latter by itself having a lesser effect than the former.