Добавил:
kiopkiopkiop18@yandex.ru t.me/Prokururor I Вовсе не секретарь, но почту проверяю Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
Ординатура / Офтальмология / Учебные материалы / Section 6 Pediatric Ophthalmology and Strabismus 2015-2016.pdf
Скачиваний:
0
Добавлен:
28.03.2026
Размер:
33.87 Mб
Скачать

CHAPTER 5

Motor Physiology

Basic Principles and Terms

Axes of Fick and Ocular Rotations

Ocular rotations have commonly been described as involving movements about the 3 axes of Fick, designated as x (transverse), y (sagittal), and z (vertical) (Fig 5-1). However, current thinking more conveniently describes ocular rotations as horizontal rotations about a vertical axis, corresponding to medial and lateral gaze; vertical rotations about a horizontal axis, corresponding to upward and downward gaze; and torsional rotations about the line of sight. The final orientation of the eye after a change in gaze position depends on the sequence of the rotations; this order, therefore, is not commutative. The most common sequence of rotations is the Fick sequence: horizontal rotation, followed by a vertical rotation, and then rotation about the line of sight. Another order is the Helmholtz sequence, which is helpful in the analysis of horizontal vergences: vertical rotation, then horizontal, and finally torsional. Small and moderate eye rotations can be reasonably approximated using the independent horizontal and vertical components as if they did not interact. This approximation is not applicable if large horizontal and vertical rotations occur simultaneously.

Figure 5-1 Axes of Fick. (Adapted with permission from Yanoff M, Duker J, eds. Ophthalmology. 2nd ed. London: Mosby; 2004:557.)

Historically, Listing’s equatorial plane was used as a reference plane for describing multiplanar eye movements. However, current thinking utilizes the concept of rotational sequencing.

Positions of Gaze

Primary position is the position of the eyes when they are fixating straight ahead. Secondary diagnostic positions are straight up, straight down, right gaze, left gaze.

Tertiary diagnostic positions are the 4 oblique positions of gaze: up and right, up and left, down and right, down and left, as well as the right and left head-tilt positions.

Cardinal positions are up and right, up and left, right, left, down and right, down and left (Fig 5- 2).