Unilateral proptosis with bilateral VI
th
 nerve palsy,diagnosis is -
Grave's disease
Retinoblastoma
Pseudotumour of orbit
Cavernous sinus thrombosis
Unilateral proptosis and bilateral 6th nerve polsy suggest the diagnosis of CST.
Bilateral 6th nerve palsy suggests the involvement of opposite side cavernous sinus. In more than 50% of the patients of CST opposite side is involved. 6th nerve is earliest to be involvement.