| 16. | Incomitance means that a strabismus differs in amounts depending on the direction of gaze or that it is present in only one position of gaze. |
| 17. | demonstrates good ocular alignment in the primary position, but... |
| 18. | a rather significant exotropia in up gaze (as seen on image18) is present. This can only be detected by doing a cover test in different positions of gaze and watching for movement of the non fixating eye. |
| 19. | shows good alignment in primary position, but a significant esotropia in down gaze. |
| 20. | demonstrates a Brown's superior oblique tendon sheath syndrome of the right eye where the involved eye fails to elevate in the adducted position. In other positions of gaze the child's eyes are straight. |
| 21. | demonstrates a Brown's syndrome of the left eye with lack of elevation in the adducted position. |
| 22. | demonstrates a type of Duane's co-contraction syndrome. In primary position the eyes are well aligned but as the child attempts gaze... |
| 23. | to the right an almost complete lack of abduction of the right eye is demonstrated. |
| 24. | This is accompanied by a widening of the interpalpebral fissure in abduction and a narrowing of the interpalpebral fissure in attempted adduction. Duane's co-contraction syndrome is caused by an absence either unilaterally or bilaterally of the sixth nerve nucleus and the sixth nerve and the lateral rectus muscle is innervated by a branch of the third nerve causing both the medial and lateral to co-contract simultaneously, limiting abduction. |
| 25. | shows a Duane's co-contraction syndrome of the left eye with complete loss of abduction. As these children want to fuse and use their eyes simultaneously they often develop a face turn to put their eyes in the opposite direction of gaze. |
| 26. | demonstrates a left face turn with good alignment of the eyes in gaze to the right. Children with constant significant face turns or head tilts should be screened for an incomitant strabismus. |