1. Examine the orbits proptosis (forward displacement of the globe)
orbital tumour — or granuloma carotid cavernous fistula -
- cavernous sinus thrombosis
— thyrotoxicosis (unilateral exophthalmos)
Investigations ■ CT/MRI scan
- CT/MR sinuses globe fixation -
orbital fracture with — tethering of the globe
CT/MRI (muscle enlargement)
2. Examine ocular movement (page 12) - note the presence of a squint or strabismus i.e. when the axes of the eyes are not parallel.
Concomitant squint (heterotropia) - an ocular disorder. The eyes adopt an abnormal position in relation to each other and the deviation is constant in all directions of gaze. Such squints develop in the first few years of life before binocular vision is established, usually they are convergent (esotropia), occasionally divergent (exotropia). Suppression of vision from one eye (amblyopia ex anopsia) results in absence of diplopia.
Occasionally patients subconsciously alternate vision from one eye to the other, retaining equal visual function in both - strabismus alternans. Correction of an underlying hypermetropia with convex lenses may offset the tendency for the eyes to converge. Paralytic squint:
- Affected eye shows limited movement.
- Angle of eye deviation and diplopia greatest when looking in the direction controlled by the weak muscle.
- Diplopia is always present.
- The patient may assume a head tilt posture to minimise the diplopia. Paralytic squint results from disturbance of function of nerves or muscles.
In the primary position, the affected eye deviates laterally (due to unopposed action of the lateral rectus) and ptosis and pupil dilatation are evident.
(Ptosis may be complete, unlike the partial ptosis of a Horner's syndrome which disappears on looking up.)
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