| 54 | Intermittent exotropia begins any time after the age of ten months up to four years. These children are initially straight with good binocularity and then suddenly develop an outward deviation of one or the other eye. |
| 55. | The deviation characteristically begins when the children are looking at distance and often their eyes are straight at near. This offers a source of confusion for the parents who have difficulty in describing to you what they are actually seeing. Often cover tests are performed in the office at near, but these children need to be taken to a window and have them fix at something in the far distance while a cover test is performed. |
| 56. | shows good alignment in the top left and bottom right photographs, but under the influence of an alternate cover test an intermittent left exotropia is visible which the child re-fuses by blinking in the bottom middle photograph. |
| 57-58. | A true alternating exotropia (SLIDE 57-58) is rare, and the children generally speaking have a dominant eye with which they prefer to fix. Characteristically these children will close their non dominant eye in bright sun light to avoid the effect of diplopia which is present early on and this is a most useful clinical question to ask the parents.Intermittent exotropia does not respond to exercises, the deviation is present mainly at distance and does not go away. |
| 59-60. | Left untreated it tends to become more constant in adulthood and can be a significant cosmetic as well as functional defect as these patients have no true binocularity at distance as would be necessary for example in driving a car (60). The treatment for intermittent exotropia is surgical, consisting of weakening and strengthening the appropriate extraocular muscles to realign the eyes. The recurrence rate of the exotropia is in the order of 35% and more than one operation may be necessary. Children with intermittent exotropia have straight eyes at least part of the time. Infants and children with monocular exotropia which is constantly present often harbour significant intraocular organic pathology (retinoblastoma, congenital cataract etc.), and should be referred to an ophthalmologist on an urgent basis, particularly if they have leucocoria (a white pupil). |