I have a problem every 1 - 2 weeks. my condition is that color fades slowly until the visual field goes black and at the extreme periphery where there is still light and vision. this lasts for about 2-3 mins and then the process reverses itself and the black fades out and the vision fades in until all is normal. there is no associated headaches or residual change in visual acuity. i am a healthy 19 yr old male.

please reply as I am on holiday in africa and am concerned about the whole thing.