Amplitude of accommodation and refractive error.

This paper investigates the amplitude of accommodation of early onset myopes, late onset myopes, emmetropes, and hyperopes. Eighty subjects were used, 41 women and 39 men, with an age range of 18-22 yr (mean = 19.82). All subjects wore an optimum refractive correction, giving visual acuities of 20/20 or better. Significant differences were found between the four refractive groups, with late onset myopes having the largest amplitude of accommodation, followed by early onset myopes, emmetropes, and hyperopes. The results are discussed in the light of previous findings on tonic accommodation and the accommodative response gradient and interpretated in the context of a dual innervation to the ciliary muscle.