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Eye tests for children with Down's syndrome

Frequency of eye tests


AgeRecommended eye examination frequency
Under 2 years oldThree to six monthly intervals
2 - 5 years oldSix monthly intervals
5 years and olderYearly intervals (if refractive error has stabilised)

Eye test techniques



Good communication is essential, as it is for all patients. On the whole, children with Down's syndrome do better at understanding the spoken word than they do at speaking themselves. So don't under-estimate a child's ability if he or she cannot talk to you. 

On the other hand, many children have hearing deficits and their auditory processing is slow, so you will need to speak a little more slowly than usual and in shorter sentences. Give any patient with Down's syndrome longer to respond to your question or instruction. If you try to rush your patient you will only end up confusing or frightening them.

Many children with Down's syndrome find it disturbing to 'fail' and are, therefore reluctant to try when tasks become difficult. When doing a visual acuity test, for example, a child may begin enthusiastically but get distracted and lose interest when the smaller targets are presented. You will get the best out of a child with Down's syndrome if you avoid reinforcing 'failure'. Try interspersing difficult targets with easy ones, give lots of praise and encouragement, and always end the procedure with a success.

Measuring visual acuity

Acuity can be measured by letter charts, letter matching, picture/symbol naming or matching, or by Preferential Looking tests (e.g. Cardiff Acuity Test ), depending on the child's age and ability. It is important to keep the child's interest and motivation in order to obtain a valid result.




Advising parents on acuity





In our study of 55 children with Down's syndrome followed from infancy, only 25% of those who had significant refractive errors at the outset showed emmetropisation. 20% of the children had no significant refractive errors at the outset but went on to develop refractive errors. Thus, failure of emmetropisation is common in children with Down's syndrome. Clinically, this means that examination intervals and prescribing guidelines drawn up for typically developing children are not applicable to children with Down's syndrome. In our clinic, we tend to prescribe spectacles earlier for children with Down's syndrome, since emmetropisation is unlikely. And we continue to examine children regularly, even if they are within the emmetropic range in infancy, since refractive errors can develop.


Accommodation is most usefully measured in young children by dynamic retinoscopy. A target that interests the child is mounted on a rule (or held freely) and set at a fixed distance. Retinoscopy is carried out initially from alongside the target. Accurate accommodation means that the retinoscope reflex at this distance will be neutral. If the child is under-accommodating, a 'with' movement will be seen and the neutral point will be further away from the child's eyes. The dioptric distance between the target position and the neutral point is the amount of under-accommodation or 'lag'.

There are published norms for children of different ages, but a useful rule of thumb is that a 'lag' of more than 0.75D is considered outside the normal range.

Our studies have repeatedly shown that the majority of children with Down's syndrome under-accommodate for near targets by a substantial amount. The mean lag for a target at 25cm (requiring 4.00D of accommodation) is 2.20D. This means that near tasks are optically blurred, putting an additional burden on the children's learning at near. If a child under-accommodates then any significant hypermetropia should probably be fully corrected. We do not yet understand the mechanism of the under-accommodation, but have found an association between under-accommodation and increased risk of significant hypermetropia and strabismus. Conversely a young child with accurate accommodation is less likely to go on to develop hypermetropia and/or strabismus, so measuring accommodation can help practitioners to decide on how frequent eye examinations should be for very young children with Down; syndrome.

Our Bifocal Trial has shown that children who under-accommodate once their distance refractive error is fully corrected, gain considerable benefit from bifocals. We now recommend bifocals for all children with Down's syndrome who under-accommodate. It is therefore essential that accommodation and near functions are measured at EVERY eye examination and children offered remediation in the form of bifocals (or varifocals) for under-accommodation.

At present, it appears that 30-40% of children who wear bifocals learn to accommodate accurately over the top of their bifocal and are able to return to single vision lenses. The children 'tell' us when they are ready to give up bifocals, by pushing their glasses down their nose and deliberately looking through the distance portion of the lens. Dynamic retinoscopy can then be used to confirm accurate accommodation.
