secondary to loss of innervation: During corrective surgery fibrous attachments have been found connecting the horizontal recti and the orbital walls and fibrosis of the lateral rectus has been confirmed by biopsy. This fibrosis can result in the lateral rectus being 'tight' and acting as a tether or leash. Co-contraction of the medial and lateral recti allows the globe to slip up or down under the tight lateral rectus producing the up and down shoots characteristic of the condition. Genetics There are two known genetic associations with Duane Syndrome. In some families the condition is associated with variants in the Chimerin 1 gene and in others it is associated with variants in the Transcription factor MafB gene. Diagnosis Classification Duane's syndrome has three variants: Type I: Limited abduction with or without esotropia Type II: Limited adduction with or without exotropia Type III: Limitation of both abduction and adduction and any form of horizontal strabismus Brown(1950) has classified Duane's syndrome according to the characteristics of the limitation of movement- Type A: with limited abduction and less-marked limitation of adduction Type B: showing limited abduction but normal adduction Type C: the limitation of adduction exceeds the limitation of abduction. There is an exotropic deviation and a head turn to compensate the loss of adduction The first type is more common and accounts for 85% of the cases. Differential diagnosis In the clinical setting, the principal difficulties in differential diagnosis arise as a consequence of the very early age at which patients with this condition first present. The clinician must be persistent in examining abduction and adduction, and in looking for any associated palpebral fissure changes or head postures, when attempting to determine whether what often presents as a common childhood squint (note-"squint" is a British term for two eyes not looking in the same direction) is in fact Duane syndrome. Fissure changes, and the other associated characteristics of Duane's such as up or down shoots and globe retraction, are also vital when deciding whether any abduction limitation is the result of Duane's and not a consequence of VI or abducens cranial nerve palsy. Acquired Duane's syndrome is a rare event occurring after peripheral nerve palsy. Treatment The majority of patients remain symptom free and able to maintain binocularity with only a slight face turn. Amblyopia is uncommon and, where present, rarely dense. This can be treated with occlusion, and any refractive error