Visual acuity and displacement threshold hyperacuity were measured in a group of patients awaiting cataract extraction, and this was repeated several weeks subsequent to surgery. In addition, measurements were made on a group of patients with various ocular pathologies but without the presence of cataract. Displacement thresholds in the cataract group increased only slightly with the severity of the opacity. On the other hand, displacement thresholds for the pathology group showed a marked dependence upon visual acuity‐the worse the acuity, the higher the threshold. This results in a clear distinction between vision loss due to optical factors (cataract) and retinal/neural factors. There was a good correlation between pre‐and post‐operative displacement thresholds in the cataract group, with post‐operative thresholds being slightly better than pre‐operative thresholds. The results suggest that this technique may offer patients a good indication of the likely quality of vision achieved following cataract e