Upper level: b2102 Quality of vision
Seeing functions of sensing a minimum amount of light (light minimum), and the minimum difference in intensity (light difference.)
(additional explanation: Visual function in which difference between visual function in which light of minimum amount (minimum light) is felt and minimum amount of strength of light (light and shade difference) is felt. )
Inclusions: functions of dark adaptation; impairments such as night blindness (hyposensitivity to light) and photophobia (hypersensitivity to light)
Lower livel: