Commercial Fixed Wing
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Confusion
Ground Event / Encounter Other / Unknown
Flight Crew Became Reoriented
Airport; Environment - Non Weather Related
On final approach into MEM on RWY18R I noticed what looked like a faint displaced threshold. This made me think I had missed a NOTAM about some construction. As we flew closer to the runway I realized it was a double image just like I had noticed in OKC about 6 months earlier. The double image is caused by the LED lighting and it appears to be like a prism or holographic effect in the windows or the aircraft. I wear glasses and so during taxi in I raised my glasses and had the same double image and my First Officer who does not wear glasses had the same double image. Also; the double image changes with seat position and is in the front and side windows. In OKC earlier I thought it was caused by the lights being step 5 but the lights in MEM were at mid-range intensity. This is a safety of flight issue that would affect your depth perception in a low visibility approach to a manual landing. I have never seen this in my entire career with regular incandescent lights. I think LED lights somehow reacting with the different layers of the aircraft windows.
Air carrier Captain reported LED lighting on Runway 18R at MEM could affect depth perception in low visibility due to prism effect.