Paediatrics: Squints (strabismus)

Squints (strabismus)

Squints are common in childhood. They occur with misalignment of the visual axes of the two eyes so that they appear to point in different direc-tions. If a squint develops in the first 7yrs, it can have a significant impact on visual development.

The causes of squint may be:

•   Idiopathic.

•   Refractive error.

•   Visual loss.

•   Ophthalmoplegia (central or peripheral).

Types of squint

There are two main types.

Concomitant (non-paralytic) squint

•   Common and usually due to a refractive error in one or both eyes.

•   Often convergent.

Non-concomitant (paralytic) squint

•   Rare and usually due to cranial (motor) nerve palsy.

•   Must exclude an intracranial lesion (e.g. brain tumour).

Describing squints

Squints are described using the following terminology.

•   Convergent: bad eye turned inwards (cross-eyed appearance)

•   Divergent: bad eye turned outwards

•   Latent: a squint that is controlled by subconscious effort and is not always apparent. In certain situations, such as fatigue, the control is lost and the squint will become ‘manifest’

•   Pseudosquint: this arises when wide epicanthic folds give the appearance of a squint, which is excluded on testing

Testing squints 

All squints should be examined using the ‘cover test’ (see Fig. 24.1).

Management

The aim of treatment is to get the ‘weaker’ squinting eye ‘trained up’ in order to prevent amblyopia. Treatments are usually under the supervision of orthoptists in co-operation with ophthalmic surgeons.

•   Correct refractive error: wear glasses.

•   Eye patch wearing on the good eye to ‘train’ weaker eye.

•   Eye muscle exercises.

•   Eye (muscle) surgery if large squint and above measures failing.

Note: A child must be seen by an ophthalmologist if squint is:

•   Divergent

•   Paralytic

•   Persistent beyond age of 2mths