eye tests and the flash photo of retina, how many times is ok?

[Sonya007]

my 9 year old son has been to vision express twice now about 2 months ago. both times they were unable to get a photo of one eye. they even seemed to have mixed up the photo they did get between left and right.

anyway my question is how many times can he safely attempt this test? as the opticians receptionist who was doing the photo said they could only attempt it twice per day.

the problem is on the previous occasions they have tried he somehow manages to blink when the flash goes off.

now it wouldn't bother me but hes been complaining of headaches usually in the evening. I think it maybe tension headaches as he plays on his ipad too long, but you also start to wonder the worst.

the problem is I don't want to take him to another optician and have the flash test if it will harm his eyes.

whats a safe amount?