American Orthoptic Journal Abstract
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Volume 50, 2000, p. 89–95
The Anatomy of Accommodation (Abstract)
Kyle A. Arnoldi, C.O., C.O.M.T.
Disorders of the accommodative mechanism are prevalent in children and adults. Accommodative convergence can have a profound influence on eye alignment in children, and presbyopia is the most common ocular condition in the world. The accommodative response results from a combination of sensory, neuromuscular, and biophysical events that work together to increase the dioptric power of the eye. Triggered primarily by blurring of the retinal image, the efferent response is generated in the midbrain and acts on the ciliary muscle, a smooth muscle that is physiologically and anatomically similar to skeletal muscle tissue.
Accommodative ability can be measured in terms of amplitude, facility, latency, gain, and amount of tonic accommodation. Each of these qualities undergoes a maturation process, or critical period, during the first few months to years of life. Many theories have been proposed to explain the deterioration of the accommodative mechanism, or presbyopia. The definitive answer is not yet known. As we learn more, we may find that many of the long accepted theories are not supported by evidence.