From Douglas Dickie
Your article on undercorrection of short sight (23 November, p 6), together with the usual media distortions that followed, have probably caused a great deal of needless anxiety for parents of children with short sight. For at least 30 years the standard practice in Britain has been to prescribe glasses that give full correction for children with myopia.
Of far more significance is whether spectacles should be worn continuously in the early stages of myopia, or only for relatively long-distance tasks such as looking at the blackboard or television. There is very strong evidence that a substantial proportion of the myopia in modern society is caused, or at least exacerbated, by the greater amount of time spent in close-up visual activities such as reading, compared with pre-literate society. In susceptible individuals myopia may be an environmental adaptation. The obvious corollary is that the use of spectacles should be limited to distances beyond which the unaided eye is unable to focus.
O’Leary’s findings may be explained if children given weaker prescriptions find reading with glasses more comfortable than they would with a full correction. If so, the message is that in the early stages of myopia, children should be encouraged not to wear their glasses all the time.
Aberdeen, UK
