Instruments: Attention please

It is an unfortunate truth that the patients for whom an objective refraction is most essential are also those least able to maintain steady fixation and relaxed accommodation for any useful period of time. The very young, the non-verbal learning disabled and some people with cognitive impairment are unlikely to find a light flashed at them either relaxing or interesting. And if they have an aversion to the test results in having drops instilled, they may develop a life-long distrust for eye care professionals.

Retinoscopy, and indeed desktop or hand-held autorefraction, is only able to give an accurate and repeatable result when the patient is able to maintain a steady gaze direction and relax their accommodation. An autorefractor may incorporate a picture such as a hot-air balloon or, as with some paediatric hand-held devices, may use a range of flashing lights or noises to maintain patient attention. Retinoscopy is preferred for less attentive patients because of the flexibility of movement it offers, but usually there is still a need to wave around a toy or use a target to encourage patient cooperation, and off-axis error and poor control of accommodation are still common.