[Effects of presbyopia on clinical phoria].

BACKGROUND

Due to accommodation-vergence cross-link we can expect that presbyopia will affect vergence as well. From investigations of cross-link as function of age one may assess strain of visual system due to presbyopia. Furthermore, this observation will give hints on innervation of ciliary muscle.

MATERIAL AND METHOD: Vergence is assessed as function of stimulus of accommodation in 27 subjects (24-65 years).

RESULTS

Presbyops tend to be exophoric for near vision. Vergence is linked to accommodation by means of a quadratic polynome rather than by a linear function.

CONCLUSIONS

We may expect, that missing vergence strains visual system of presbyops. Results support Hess-Gullstrand theory of presbyopia and indicate a loss of innervation of ciliary muscle with increasing age.