Intermittent Distance Exotropia (IDEX)

What are the typical features of an IDEX and how are patients assessed in the orthoptic clinic?

Video Transcript:

Intermittent Exotropia

The most common form of exotropia in childhood is an Intermittent Distance Exotropia (IDEX).

What are the features of an Intermittent Distance Exotropia?

  • - One eye diverges (moves outwards) when the child is looking at an object in the distance. This may be most obvious when the child is staring into space or day-dreaming. A child rarely has any accompanying symptoms, such as double vision, but you may notice their eyes straighten when engaging their attention. Most children are able to hold their eyes together when they are looking at a near target, or when reading. This is because they are using their convergence to overcome their divergent squint.
  • - Sometimes there is a tendency for closing one eye, particularly on bright, sunny days and the eye may turn out when it is reopened.
  • - Amblyopia is rare in IDEX.
  • - Refractive errors - Most children with IDEX do not have a significant refractive error.
  • - Most children with IDEX have good stereopsis, however if their stereopsis appears to be deteriorating this would be one reason to consider corrective surgery.