The ocular phenotype in ACHM4 is similar to that of other forms of achromatopsia. Nystagmus, poor visual acuity, photophobia, and defects in color vision are usually present. Some subjects, however, retain some color discrimination, a condition referred to as incomplete achromatopsia. The ERG documents the absence of cone function but normal rod responses. The retina appears normal clinically.
Few families have been reported and the complete phenotype remains undocumented. For example, it has been reported that visual acuity weakens with age in some patients although it is uncertain if this is true of all cases.
