Purpose: To establish benchmark standards for refractive outcome after cataract surgery in the National Health Service when implementing the 2004 biometry guidelines of the Royal College of Ophthalmologists and customising A constants.
Methods: Three cycles of prospective data were collected throughout the cataract care pathway on all patients using an electronic medical record system (Medisoft Ophthalmology), between January 2003 and February 2006. The electronic medical record automatically recommends the formula to be used according to the College guidelines and allows A constants to be customised separately for either ultrasound or partial coherence interferometry methods of axial length measurement and for different intraocular lens models. Consultants and trainees performed routine phacoemulsification cataract surgery and new intraocular lens models were introduced during the cycles. Uncomplicated cases with 'in-the-bag fixation', achieving 6/12 Snellen acuity or better were included. Community ophthalmic opticians performed refraction at 4 weeks.
Results: The postoperative subjective refraction was within 1 D of the predicted value in 79.7% of the 952 cases in cycle 1, 83.4% of 2406 cases in cycle 2, and 87.0% of 1448 cases in cycle 3.
Conclusions: On the basis of our data, using College formula, optimising A constants and partial coherence interferometry, a benchmark standard of 85% of patients achieving a final spherical equivalent within 1 D of the predicted figure and 55% of patients within 0.5 D should be adopted.