Size of the lens nucleus separated by hydrodissection.

We measured the extracted central nucleus (diameter and thickness) of 88 eyes (average patient age, 72 years) undergoing extracapsular cataract extraction (ECCE). The average diameter was 6.51 +/- 0.75 mm; the average thickness, 2.96 +/- 0.33 mm. Since the average lens diameter is approximately 10 mm, a corneoscleral incision of 7 to 8 mm in chord length should be sufficient for its removal in most ECCE cases. Accumulation of these data and further analysis correlating them with age and degree and type of cataract in larger series will be useful in determining the smallest possible incision size required for individual patients.