If the inserted consecutively longer than eight hours per day, it will make our eyes to the lack of oxygen. Because if the eyes, lack of oxygen for may will affect the blind at all.
If consecutive than 8 hours per day, it makes our eyes hypoxia. If hypoxia eye contact for a long time. May adversely affect the size of blindness at all.
If you put too long a day, 8 consecutive hours. It will make our eyes lack oxygen) because if the eyes lack of oxygen for long time. May this size is blind.