[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.


METHODS
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.
Institut für Hygiene und Arbeitsphysiologie, Eidgenössische Technische Hochschule, Zürich.
M
M
Menozzi
H
H
Krueger
D000065:Accommodation, Ocular / Q000502:physiology; D000328:Adult; D000368:Aged; D002924:Ciliary Body / Q000294:innervation; D003290:Convergence, Ocular / Q000502:physiology; D004215:Distance Perception / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000175:diagnosis / Q000503:physiopathology; D011305:Presbyopia / Q000175:diagnosis* / Q000503:physiopathology; D013285:Strabismus / Q000175:diagnosis* / Q000503:physiopathology