Orbit. Dr. Mohammad Shehadeh. Anatomy. The orbit is a pear-shaped cavity, the stalk of which is the optic canal (Fig. 3.1). The intraorbital portion of the optic nerve is longer (25 mm) than the distance between the back of the globe and the optic canal (18 mm).
Dr. Mohammad Shehadeh
Soft tissue involvement
tests may be used to differentiate a restrictive from a neurological motility defect:
Positive result: difficulty or inability to move the globe indicates a restrictive problem such as thyroid myopathy or muscle entrapment in an orbital floor fracture.
Negative result: no resistance will be encountered in either eye if the muscle is paretic as a result of a neurological lesion.
Positive result: an increase of 6 mmHg or more denotes resistance transmitted to the globe by muscle restriction (Braley sign).
Negative result: an increase of <6 mmHg suggests a neurological lesion.
Saccadic eye movements in neurological lesions are reduced in velocity, while restrictive defects manifest normal saccadic velocity with sudden halting of ocular movement.
a) soft tissue involvement,
(b) lid retraction,
(d) optic neuropathy and
(e) restrictive myopathy
Goal is to achieve binocular single vision in the primary and reading positions.