METHOD FOR DETERMINING INDICATIONS FOR SURGERY OF NYSTAGMUS ASSOCIATED WITH STRABISMUS Russian patent published in 2023 - IPC A61F9/07 A61B3/00 

FIELD: medicine; ophthalmology.

SUBSTANCE: videonystagmography is performed, while the patient has a special structure on consisting of a spectacle frame with two infrared cameras and a laser pointer projecting a test object, the structure is connected to a personal computer. To measure the angle of strabismus and parameters of nystagmus, the centre of the pupil of the fixing eye is taken as a reference point, and if one eye is covered, then fixation appears on the other. The zero position for this eye is determined, the zero position for the other eye is determined in the same way, under conditions of head fixation, the patient is asked to look directly at the test object, which is projected by a laser pointer onto a screen located at the level of the patient's eyes at a distance of two meters. In this case, the test objects are placed with an offset of 30 prism diopters from the central mark; first, the amplitude and frequency of oscillatory eye movements are obtained in a straight head position. Next, the patient is asked to look in nine directions of gaze alternately: with two open eyes, covering the right eye and covering the left eye, the amplitude and frequency of oscillatory eye movements are obtained in nine directions of gaze. Then the patient's head is no longer fixed and the patient is asked to look at the central test object, thereby the indicators of the amplitude and frequency of oscillatory movements in the conditions of the forced position of the head are determined; during the entire study, the horizontal and vertical angles of strabismus are automatically calculated depending on the displacement of the pupil from the given position during fixation expressed in degrees. After that, the position of the eyes at which the frequency and amplitude of oscillatory movements decreases or disappears completely is determined, which is the blocking point of nystagmus. And if the angle of strabismus is more than 10 degrees and the coordinates of the nystagmus blocking point are unstable and change depending on the fixing eye, then the surgery is performed in two stages, the first of which is the correction of the angle of strabismus by recession of the internal rectus muscle, and after stabilization of the nystagmus blocking point, the second stage is correction of nystagmus by recession of the rectus muscles of the eye, ipsilateral to the direction of gaze, in which the blocking point of nystagmus is determined. And if the angle of strabismus is less than 10 degrees and the coordinates of the nystagmus blocking point are stable, then surgical treatment is carried out in one stage by recession of the rectus muscles of the eye, ipsilateral to the direction of gaze, in which the nystagmus blocking point is determined, while the magnitude of the recession performed corresponds to the angle of strabismus in this direction gaze.

EFFECT: method allows to accurately determine the nystagmus blocking point for calculating the dosage of surgical treatment, as well as to minimize the amplitude and frequency of involuntary oscillatory eye movements in a straight head position, level torticollis, and eliminate accompanying horizontal deviations.

1 cl, 2 ex