Adaptation to Progressive Additive Lenses: Potential Factors to Consider.

People develop presbyopia as part of the normal aging process. Most presbyopes adapt to progressive additive lens (PALs), while others do not. This investigation sought to determine whether the ability to modify disparity vergence or phoria was correlated to PALs adaptation.

The influence of age on adaptation of disparity vergence and phoria.

A paucity of research exists to investigate whether the normal aging process influences the ability to adapt disparity vergence and phoria. Vergence eye movements and dissociated phoria were recorded from 49 healthy subjects (ages 20-70years) using an objective eye movement tracking system. Four-degree vergence responses were modified using a double-step protocol.

Short-term adaptations of the dynamic disparity vergence and phoria systems.

The ability to adapt is critical to survival and varies between individuals. Adaptation of one motor system may be related to the ability to adapt another. This study sought to determine whether phoria adaptation was correlated with the ability to modify the dynamics of disparity vergence.

The relationship between phoria and the ratio of convergence peak velocity to divergence peak velocity.

Purpose: The purpose of this study was to investigate the relationship between phoria and the dynamics of vergence eye movements as described by the ratio of convergence average peak velocity to divergence average peak velocity, termed the vergence peak velocity ratio.

Methods: Phoria and vergence step responses were recorded. Three measures of phoria were assessed: baseline phoria, which is the initial phoria measurement; adapted phoria, which is the phoria measured after a visual task; and change in phoria, which is defined as adapted phoria minus baseline phoria.

Sustained convergence induced changes in phoria and divergence dynamics.

Purpose: The purpose of this study was to investigate how sustained convergence induces phoria adaptation and changes divergence dynamics.

Methods: Near dissociated phoria and divergence step responses were recorded using an infrared eye movement monitor on four binocularly normal subjects. We tested three different adapting vergence positions (16 degrees , 6 degrees , and 0.

Quantification of heterophoria and phoria adaptation using an automated objective system compared to clinical methods.

Purpose: To develop a system with which to quantify objectively the heterophoria to be measured throughout eye movement experiments. This study compared precision, resolution and accuracy characteristics of a limbus eye movement tracking system to the alternate cover test and the Maddox rod.

Methods: Precision testing was performed using each technique with binocularly-normal subjects at different test sessions.

Vergence transient component: an index to oculomotor learning modification.

The brain has a dynamic ability to change or adapt which is imperative for survival of a species. Research has shown that the dynamics of disparity vergence eye movements, the inward (convergence) or outward (divergence) turning of the eyes, are malleable and depend to some extent on the amplitude of preceding stimuli. Disparity convergence is composed of two components.