Ophthalmology:  A large study confirms what was demonstrated a year ago. If one gets a refractive error after the first cataract surgery, one should aim the second IOL selection to half that error. In other words, if the first eye ends up at +1.50, one should increase the IOL power for the second eye by 0.75. This held true for all IOL formulas (Hoffer, SRK/T) and for small and larger errors.  One small caveat was that this did not hold up when inter-corneal powers differed by >0.60. The authors suggest that the position of the IOL in the eye, a hard thing to predict, is the source of the error.