Double vision when seeing with both eyes can be due to a range of conditions.
Causes of binocular diplopia:
(1) paralysis of one or more extraocular muscles (often due to third, fourth or sixth cranial nerve palsy)
(2) aniseikonia (difference in image size perceived between the eyes due to unequal magnification).
(3) heterophoria (due to orbital tumor, cellulitis, other)
(4) narcolepsy
(5) physiologic diplopia
(6) psychogenic diplopia
(7) large surgical overcorrection
(8) cyclotropia after surgery on oblique muscle
(9) paradoxical diplopia (anomalous retinal correspondence with or without amblyopia)
(10) after surgical correction of a retinal detachment
(11) congenital or developmental deficiency of fusion ("horror fusionis")
(12) divergence paresis
