Patients about to undergo cataract extraction were assessed clinically using several criteria to try and judge the necessity for biometry. The patients judged not to need biometry were allocated randomly to two groups, one of which had biometry.
The only significant clinical criterion for biometry was found to be the wearing of glasses since before the age of 30 years. Several unexpectedly high refractive errors occurred in the group of patients who did not have biometry. In the group of patients judged not to need biometry but allocated to the biometry group, refractive results were significantly better (nearer to target refractions) than in the unmeasured group.
Routine pre-operative biometry is probably the only way to avoid unexpected high ametropia, and it also improves the refractive results. There is however much room for improvement in the accuracy of biometry.
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Thompson, S., Mohan-Roberts, V. Clinical indications for intraocular lens power calculation: A prospective randomised study. Eye 3, 696–703 (1989). https://doi.org/10.1038/eye.1989.107
International Ophthalmology (2008)