Electrophysiological testing of eyes with opaque media

Electrodiagnostic tests as applied to the eye are now widely used in the investigation of patients with inherited retinal degenerations but their value in patients with opaque media is perhaps less well recognised. The choice of stimulus is all important and a flash VEP and flash ERG probably provide the best combination of tests at present. A comparison with the fellow eye, if it is normal, greatly improves the value of the result. A pitfall of this type of test is its failure to detect amblyopia and a carefully recorded history is important in helping to interpret the traces.