The accuracy of IOL calculation using the SRK II formula was studied i
n 515 cataract extractions with posterior chamber IOLs. All excessivel
y myopic patients (8 patients) and those where we had predicted an emm
etropic postoperative result, from a consecutive series of 994 patient
s, were included, Preoperatively the patients were divided into differ
ent groups according to their refractive status and the mean postopera
tive refraction was calculated in each group. The mean postoperative r
efraction increased almost linearly with increasing myopic status, The
emmetropic group achieved a mean postoperative refraction of - 0.6 D,
whilst in the most myopic group mean refraction was - 1.8 D, We belie
ve that the SRK II formula is inaccurate for myopic eyes, and that new
formulas are needed, taking into account all those factors that make
up the dioptric power of an eye.