In this study, the authors assessed retinal sensitivity before and after cataract extraction, in an effort to understand how lens opacities may affect microperimetry results in glaucoma and macular diseases. Thirty patients awaiting cataract extraction were examined and their lens opacities were graded using the LOCS II classification system. Microperimetry measurements were then taken of the central 20° field, which allowed the median retinal sensitivity across that field to be calculated. These measurements were repeated in the postoperative period. Median retinal sensitivity significantly increased following cataract extraction, by 4dB. Patients with posterior subcapsular cataracts had, on average, the lowest retinal sensitivity and also had the greatest postoperative increase in sensitivity compared to patients with nuclear or cortical cataracts. Although small and preliminary in nature, this study provides evidence that the presence of a cataract (particularly posterior subcapsular) can affect microperimetry results. This may be important when interpreting microperimetry in macular diseases.