Author: Moulakaki A., I. BSc, MSc, University of Valencia
Nowadays, it is well established that the amplitude of accommodation decreases with age. However, the age related changes in the dynamics of accommodation are not well characterized. Hence, studies on the accommodative dynamics provide insight into the accommodation mechanism and the factors that influence on the accommodative responses. This results to gain knowledge of the age related changes in the accommodative dynamics induced with conditions, such as presbyopia. Furthermore, although there are potentially many effective methods for treating presbyopia (e.g. spectacles, multifocal contact lenses, monovision, etc), it is of great interest to manage the true restoration of active and dynamic accommodation, as it would provide a dynamic change in optical power of the eye with an effort to focus at near.
A preliminary study aimed to investigate if age-related changes have an effect on the ocular dynamic accommodative characteristics and to identify the impact of accommodative IntraOcular Lens on the aging accommodative system. To achieve this, continuous dynamic responses recorded with a moving target, while subject’s aberrations have been removed and replaced with those of pseudophakes viewing with the lens. In particular, the intraocular structures that dominate dynamic accommodative system changed with aging and the progression of presbyopia. Moreover, the dynamic accommodating effects of the lens appeared to be limited, however subjects viewing with this lens were able to track a moving target and achieve an adequate visual acuity. Pseudophakic accommodative responses were similar in dynamics with the presbyopic accommodative responses.
Figure 1: Dynamic accommodation measurements (in D) for different stimulus magnitudes
(Source: Kasthurirangan, S. (2014). Current Methods for Objectively Measuring Accommodation. In: Developing Novel Endpoints for Premium Intraocular Lenses. American Academy of Opthahlmology.)
Figure 2: Objective amplitude of accommodation (dashed line) and dynamics of the lens (solid line) of one subject(Source: Wolffsohn J. S., Hunt, O. A., et al. (2006). Objective Accommodative Amplitude and Dynamics with the 1CU Accommodative Intraocular Lens. Invest Ophthalmol Vis Sci, 47, 1230-1235.)