Maintenance of mydriasis with epinephrine during cataract surgery

The pupillary response to various doses of intraocular epinephrine (0.1 ml of 1:16,000, 1:32,000, 1:64,000, 1:80,000, or 1:96,000) was studied in 55 consecutive patients during extracapsular cataract surgery. The 1:16,000 epinephrine concentration provided a mean 0.74 mm increase in pupil diameter (range 0.0 to 1.7 mm) when administered to re-dilate the pupil after nucleus expression. The mean increase in pupil area with 1:16,000 epinephrine was 27% which greatly facilitated removal of lens cortex in most cases. However, 25% of all pupils failed to dilate with epinephrine 1:16,000. The other concentrations provided essentially the same mydriasis as the 1:16,000 concentration. Pupils smaller than 6 mm dilated more easily than pupils larger than 6 mm. Iris color, age, or sex had no significant effect on the mydriatic response. It is concluded that an extremely dilute concentration of epinephrine (i.e., 1:96,000 or less) may be effective in maintaining mydriasis during cataract surgery.