Pathogenesis of unilateral proptosis.

A series of 34 patients presenting with unilateral proptosis has been studied in order to evaluate the mechanism of proptosis. It is observed that symmetrical (axial) proptosis is usually the result of generalised increase in intraorbital contents and occurs in thyroid disease and with intracranial lesions lying remote from the orbit. Rarely, in myasthenia gravis, it may be caused by myogenic paralysis of the extraocular muscles. Asymmetrical proptosis is the result of localised increase in intraorbital contents, and this occurs with expanding lesions of the orbit and in lesions arising from neighbouring structures and enroaching the orbit.