Author: Moulakaki A., I. BSc, MSc, University of Valencia
The amount of studies conducted for estimating the age related effects in both structural and functional components of the human visual system has been remarkably increased the last two decades. However, prior to investigating the age related loss of eye’s ability to focus at different distances, it is of major importance to understand how the young eye behaves, as there are other sources of variation that influence on the optical quality during accommodation. In a preliminary study conducted for the needs of the XXXII European Society of Cataract and Refractive Surgery (ESCRS) congress, we examined the relationship between visual acuity and accommodative response, as a function of age, for natural pupil size among young normal subjects. To achieve this, a maximum likelihood adaptive procedure was employed in a healthy population with unblurred and blurred Landolt Cs stimuli sets (Figure). Minor differences were found in the measured accommodative response for each of the conditions presented. An over-accommodation and an under-accommodation were detected for the further and closer targets, respectively. Visual acuity for the distant stimuli was significantly poorer than for the other conditions, due to increased accommodative lead associated with proximal accommodation. The accommodation response was deteriorated with the most blurred stimuli, as the accommodation system was made optimal use of its available amplitude and depth-of-focus of the eye.
Figure: Unblurred and blurred Landolt Cs images generated with artificial blur to the stimulus.