Scotopization and pseudoprotanomaly in blue-yellow/colour vision defects

Pathologic scotopization: a shortened Nagel-II anomaloscopic micro-screw method

The Nagel-II micro-screw method uses eleven colour equations between 620 and 560 nm. The luminance settings are given and are based on the data of colour normal individuals. In the shortened version, intended to detect pathologic scotopization, it is ascertained at which position of the micro-screw the patient's colour adjustments drop beneath the level of 60 scale Units. A total of 64 patients was examined. 29 congenital colour defectives and 35 acquired colour defectives. With the shortened micro-screw method the patients can be divided into four groups: (1) a group without pathologic scotopization, which includes congenital protan defectives: (2) a group in which pathologic scotopization starts; (3) a group with evident pathologic scotopization, due to Stargardt's disease and other cone dystrophies; and (4) a group with complete pathologic scotopization, which includes the congenital achromats and the end-stages of the cone dystrophies.

Colour vision in retinitis pigmentosa. Influence of cystoid macular edema

In retinitis pigmentosa patients the effect of cystoid macular edema on colour vision was studied. The occurrence of cystoid macular edema decreases with increasing colour vision defect. The mutual proportion of the main types of colour vision defects remains stable until visual acuity has dropped to 0.5; at lower VA levels the number of red-green defects increases. Neither the finding of a blue-yellow colour vision defect in FM100 Hue testing nor the appearance of anomaloscopic pseudoprotanomaly is influenced by cystoid macular edema. The authors conclude that cystoid macular edema in retinitis pigmentosa patients mainly affects visual acuity and not colour vision. They also noted a familial occurrence of cystoid macular edema.