It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Most often in the past it has referred to retinal migraine, a rare type of migraine that has severe visual disturbances or blindness in one eye during an attack.
Visual distortions due to migraine have been said to have inspired Lewis Carroll in his book Through the Looking Glass.