KCNV2 and night blindness: Clinically, KCNV2 is characterized by variable age of onset, usually in infancy or early childhood, color vision defects (most commonly in the red–green axis), impaired adaptations to different light conditions, mild photophobia and nyctalopia.10, 11, 12, 13, 14, 15 In young patients, clinical presentation can be variable, the most common presentation being abnormal head position, head shaking, and nystagmus that improves with time.10