Ciliary Muscle Effort in Accommodation

Haploscopic measurements of the accommodation associated with voluntary vergence were made under normal viewing conditions, after the instillation of a parasympathomimetic drug, and after the instillation of a parasympatholytic drug. The results show that the amplitude of accommodation is increased with the parasympthomimetic drug and is decreased with a minimum amount of parasympatholytic drug suggesting that maximum ciliary muscle contraction is necessary to produce maximum accommodation at any age. They also suggest that the loss of accommodative ability with age is not due entirely to a gradually increasing sclerosis of the lens fibers from the periphery to the center of the crystalline lens.