The transient component of disparity vergence maybe an indication of progressive lens acceptability.

Presbyopia, a degenerative condition, which decreases accommodation, sets in approximately at the age of forty. One approach to correct presbyopia is the use of bifocal or progressive lenses. Naturally, some people are more prone to adapt to wearing progressive lenses than others. The vergence system, which controls the inward and outward turning of the eyes, is a system which supports viewing objects in depth. Identifying the two components (transient and sustained components) of a pure vergence eye movement is possible with ICA (independent component analysis). Preliminary results suggest a correlation with the magnitude of the transient component and whether or not a person can adapt to wearing progressive lenses or not. Furthermore, the transient component of vergence is hypothesized to be an index of how flexible the vergence system is in adapting to new environments.