Troilo D. Characteristics of accommodative behavior during sustained reading in emmetropes and myopes

The role of accommodation in the development of a refractive state remains unclear. Studies in animals and humans have suggested that a relationship, if one exists, may involve inaccuracies in accommodation during nearwork. Additionally, studies of accommodation typically look at the response over brief periods of time under controlled visual environments. We studied various dynamic characteristics of accommodative behavior during sustained periods of reading in human emmetropes and myopes and during an operant conditioned near visual matching task in rhesus macaques in order to define any relationships between accommodative behavior and the development of myopia. METHODS Humans: Accommodation was binocularly measured with an infrared photorefractor (PowerRefractor) in twenty young adults with stable refractive errors ranging from +0.50D to-7.0D during sustained reading at several distances (1.5D, 2.5D, and 3.5D). All subjects were measured with pupil dilation (2.5 % phenylepherine) and full correction. Accommodative response, errors, and accommodative variability, including power spectrum analysis, were- iv-analyzed over the entire reading period. Relationships between accommodative characteristics and changes in accommodative demand and refractive error were determined