The relation of myopia and astigmatism in developing eyes.

The relation of astigmatism and myopia was analyzed in 298 myopic children, ages birth to 10 years. The mean spherical equivalent, determined by cyclopentolate retinoscopy, for the entire group was--2.9 diopters and did not change significantly with age. However, in 3-year-old children and younger, myopia progressed in eyes with greater than or equal to 1 diopter of cylinder and tended to increase through age 8 years in those having greater than or equal to 3 diopters of cylinder. Also, astigmatic errors greater than or equal to 1 diopter, especially of oblique orientation, were associated with higher degrees of myopia than nonastigmatic errors. These data from myopic children suggest that uncorrected astigmatism during a period of visual immaturity influences the course of myopia. Thus, naturally occurring astigmatic errors, that are frequent among infants and young children, appear to have a role similar to the vision blurring perturbations that trigger the development of myopia in young animals. Ascertainment and full correction of these refractive errors in young children may be important in assuring the best possible vision.