Functional morphology of accommodation in the raccoon.

The raccoon (Procyon lotor) is a small carnivore which eats in the upright position, using hand- and finger-like front paws and digits to wash, hold and examine its food at close range. These anatomic and behavioral characteristics prompted structural and functional studies of the accommodative capability of this species. By light and electron microscopy, we observed a prominent ciliary smooth muscle and zonular apparatus.

Accommodation and presbyopia in the human eye. 1: Evaluation of in vivo measurement techniques.

As part of a cross-sectional study of aging of the human accommodative apparatus, unaccommodated anterior chamber depth, unaccommodated lens thickness, and accommodative amplitude were each determined by two or more independent techniques in 100 normal emmetropic subjects, age 18-70 yr. For anterior chamber depth, the order of accuracy seemed to be: optical pachymetry > slit-lamp Scheimpflug photography > Ascan ultrasonography, although there was good agreement among all three methods. For lens thickness, slitlamp Scheimpflug photography seemed more accurate than A-scan ultrasonography when the generally accepted lenticular sound velocity of 1641 m .

Accommodation and presbyopia in the human eye--aging of the anterior segment.

Ocular biometric parameters and accommodative amplitude were measured by various techniques in 100 normal emmetropic human subjects age 18-70 yr. Anterior chamber depth decreased and lens thickness increased linearly over the entire age group. Accommodative amplitude declined linearly until a stable nadir was reached at about age 50 yr.