Influence of pathologic scotopization on the extended Rayleigh match.

Pathologic scotopization, an important symptom of retinal disease, can be studied by means of the Nagel II anomaloscope. This method is called the micro-screw method. The micro-screw method was performed in 14 congenital and 13 acquired colour vision defective individuals. The method proves to be useful in detecting symptoms of rod intrusion in colour vision under photopic conditions.