Is having headache pain above one eye a sign of retinal detachment?

No pain with RD. Signs of rd are those seen by examining eye doctor: subretinal fluid, retinal tear, pigment cells in vitreous, and pvd. The symptoms that a patient experiences are painless progressive loss or greying; of vision which may involve the central vision. This may be proceeded by flashes and floaters. Sometimes an rd can by asymptomatic, and therefore it is important to get checked.
No. I have had retinal detachment, and there was no pain. It usually causes an area of your vision to disappear. When you stand in front of a mirror, you may notice that you can't see part of the reflection. You will need to cover one eye at a time to see if the image is different in each eye. If you suspect a detachment, it is important to see an ophthalmologist as soon as possible.