Refraction is an important part of the paediatric eye examination but can sometimes be challenging. If a child struggles to co-operate with the eye examination, how can one ensure that the best outcome is achieved? There are tips here which will hopefully help you to achieve accurate refractions in children.
Refraction can be categorised into an objective technique (cycloplegic refraction or Mohindra retinoscopy) or a subjective technique (trial frame or phoropter). Retinoscopy is the best screening tool for detection of refractive error and should always be performed as a starting point, even if a subjective refraction is indicated. This article will thus concentrate on tips for objective refraction / retinoscopy.
An objective refraction is used to establish the refractive status of infants and preverbal / nonverbal patients. A cycloplegic refraction is preferable, due to the active accommodation in a child. If the child needs to be dilated for a full fundus examination, refraction can be performed at the same time. A child who is pseudophakic / aphakic does not need cycloplegia for an accurate refraction (but it may be helpful if the pupil is very small).
Sometimes a large pupil can be a hindrance to retinoscopy, for example in aniridia. In these cases, the central reflex should be focused on rather than the peripheral reflex. However, if a child has a subluxed lens, you must decide whether it is best to prescribe for the aphakic portion of the visual axis or for the result through the natural lens. Retinoscopy results are determined through the appropriate section which will be dependent on how subluxed the lens is.
It is advisable that the person instilling the cycloplegic eye drops is not the same person performing the refraction, so that the child does not associate the discomfort of the drops with the examiner. If the child is still anxious / unsettled, remember that retinoscopy can be performed anywhere. Be prepared to be flexible and adapt your approach for the child. The more co-operative the child is, the more accurate the result will be.
Trial frames can be heavy, even those designed for children, so it is best to use lens racks or loose lenses when performing retinoscopy. The trial frames can be put on momentarily at the end if required to ensure the back vertex distance and cylinder axis is accurate.
An important variable to bear in mind is the working distance. Most clinicians perform retinoscopy at either 2/3m and remove 1.50D from their retinoscopy result; or they work at 1/2m and remove 2.00D from their retinoscopy result. However, in small children / babies, we instinctively tend to get closer, so it is necessary to be mindful of your working distance and adjust the power of the final result accordingly.
If the child has a high prescription and already wears glasses, it is useful to perform retinoscopy over their glasses. This ensures that the back vertex distance is constant. It also means that the end result will be reached more quickly. If doing this, the glasses should be focimetered to ensure the final prescription is correct. If there appears to be a change in cylinder axis, it is best to remove the glasses and check the astigmatism.
Retinoscopy can still be performed on a sleeping child but a parent / colleague may need to assist and gently lift the child’s eyelids – it is challenging to hold the eyelids, the retinoscope and the trial lenses. It is also important to try to stay on axis, especially if they have a strong Bell’s reflex. If they are lying down (perhaps in a pram, or on the operating table during an examination under anaesthesia), the clinician should try to position themselves directly above the child.
Similarly, when refracting a child with a large angle strabismus, it can be hard to stay on axis in the squinting eye. It can help to cover or patch the non-squinting eye, so that the child fixes with the eye being tested.
If after cycloplegia a dim retinoscopy reflex is noted, a high-powered plus lens and then a high-powered minus lens should be tried. This is because the further away from the correct prescription you are, the dimmer the retinoscopy reflex. If the reflex remains dim (perhaps due to corneal / lens opacity), try getting closer (for example 20cm) to the patient, but remember to adjust the power for the working distance accordingly.
To help with speed and maximise co-operation, it is possible to estimate how close the end point is based on the appearance of the reflex. For example, if there is a dim, narrow, slow reflex moving in the same direction as the beam, a +5 lens could be tried. If there is then still a ‘with’ movement but the reflex is now bright, wide and fast, a +7 lens could be tried. If this is now an ‘against’ movement, a +6 lens would be tried and then can be fine-tuned until it is neutralised (see Table 1).
Table 1.
Mohindra retinoscopy
If the child does not need to be dilated for a fundus exam and / or if there are contraindications to using a cycloplegic, retinoscopy can still be performed, but it is important to control the child’s accommodation. This can be done using a technique called Mohindra retinoscopy as below:
- Seat the child comfortably either on their own or on the parent’s lap and occlude one eye.
- Turn off all the room lights to ensure total darkness so the child can’t see any visible target. Encourage the child to focus on the retinoscope light.
- Perform the retinoscopy at 50cm from the patient. As with cycloplegic retinoscopy, use loose lenses or lens racks.
- Instead of removing the usual working distance, remove 1.25D from the retinoscopy result to determine the final prescription.
- Repeat all the above on the child’s other eye.
Dynamic retinoscopy
If accommodative lag is suspected, dynamic retinoscopy can be performed. This obviously needs to be done without dilation and is a reason to consider Mohindra retinoscopy instead of cycloplegic refraction. The child should wear their distance prescription and focus on an accommodative target in line with the retinoscope. It is based on the theory that if an individual is accurately accommodating, when a retinoscope is held alongside a target they are focusing on, a neutral reflex should be observed. If the child has a ‘lag’ of accommodation, the reflex will be a ‘with’ movement. If more than 1D is needed to achieve a neutral reflex, then there is reduced accommodation and a +2.50 add should be prescribed.
Table 2: Guidelines for prescribing glasses in young children [2].
Prescribing
Once retinoscopy has been completed, the art of prescribing can begin. Table 2 gives guidelines from the American Association of Ophthalmologists for preventing amblyopia. Lower refractive errors may warrant prescribing when strabismus or other risk factors are present. It is important to note that these values were generated by consensus and are based solely on professional experience and clinical impressions, because there is currently no scientifically rigorous published data for guidance. They are presented as general guidelines that must be tailored to the individual patient.
References
1.http://one.aao.org/CE/PracticeGuidelines/
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[Link last accessed September 2025]
2. Harvey EM, Miller JM. Prescribing eyeglass correction for astigmatism in infancy and early childhood: A survey of AAPOS members. J AAPOS 2005;9:189–91
Declaration of competing interests: None declared.
