Skip to Content


Pronunciation: pro'ta-no'pe-a

Definition: A form of dichromatism characterized by absence of the red-sensitive pigment in cones, decreased luminosity for long wavelengths of light, and confusion in recognition of red and green.

[G. protos, first, + a- priv. + ops (op-) eye]

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.