Sir,

Occasionally a patient with medical training will experience the symptoms of a disorder that may provide a unique opportunity to determine the exact nature of the symptom. This has occurred in the past with lightning flashes from posterior vitreous detachment (PVD) because Moore published the findings of his own photopsia in 1947.1 We describe an ophthalmologist colleague who suffered bilateral PVD with specific symptoms of black flashes for a brief period before the onset of the typical lightning flashes. One of the authors (LW) a 51-year-old female ophthalmologist with −5.5 D right eye and −6.0 D left developed acute PVD in the left eye. The first symptoms she noticed were black coloured flashes in the inferotemporal periphery. These were momentary, vertically orientated and occurred in a flickering pattern before subsiding and then returning again. After 6 h, they were replaced by white flashes and floaters. She was examined by THW and found to have a PVD with Weis ring. Seven years later, she developed in the right eye a similar pattern of black flashes for 2 h before they were replaced by white flashes and floaters from PVD (confirmed by THW). We suspect that many patients forget or disregard this initial symptom because these flashes are soon replaced by white lightning flashes. Since the presentation by LW, we have on specific questioning found black flashes to be present in other individuals with PVD. The symptom may be due to traction on the axons of the surface of the optic nerve by the vitreous as the PVD process creates the Weis ring thus interrupting the signal from the retina. The fact that the PVD has not yet occurred is suggested by the appearance of floaters and white lightning flashes only after the black flashes have disappeared. Evidence that the PVD process can be traumatic to the optic nerve head can be seen in some patients who develop haemorrhages on the surface of the optic nerve head after PVD.2, 3 This is the first description of black photopsia in PVD that we are aware of.