The colour receptors in amblyopia investigated by specific quantitative perimetry

With a method combining static colour perimetry and the two-colour threshold technique of Stiles, characteristic sensitivities of the cone mechanisms have been studied in amblyopic eye; the depression was more pronounced the higher the degree of amblyopia. For the blue cone mechanism no significant difference was found between the amblyopic and non-amblyopic eyes. For the red and green cone mechanisms, a central depression of sensitivity was found between the amblyopic and non-amblyopic eye, except at the fixation point where the mean threshold sensitivity was significantly higher in the amblyopic eye than in the leading eye. By registration of blue receptor curves, a distinct age factor was observed. In the younger patients (aged 10--16) the sensitivity level at peripheral positions for both the amblyopic and the non-amblyopic eye was significantly higher than in the older patients (aged 39--50). This difference is evidently due to the higher absorption of blue light in the ocular media in older patients. In our cases with eccentric fixation, the true fovea represents the relatively best sensitivity of the red as well as of the green cone mechanism.