We studied 400 eyes which underwent cataract extraction with posterior chamber intraocular lens (IOL) implantation to compare the predictive accuracy of various IOL power calculation formulae. The new Sanders-Retzlaff-Kraff (SRK) II formula was more accurate than the original SRK and Binkhorst II formulae. Modification of the A constants used in the SRK II formula to make it 'surgeon specific' ...

A series of 50 eyes received an intraocular lens (IOL) of power calculated for emmetropia from data of axial length, corneal curvature, and postoperative anterior chamber depth by R. D. Binkhorst's formulae. The postoperative refraction results were compared with those of 100 control eyes which received +19 D standard power IOLs without calculation. The calculated group had postoperative refrac...

PURPOSE To identify and quantify sources of error in the refractive outcome of cataract surgery. SETTING AMO Groningen BV, Groningen, The Netherlands. METHODS Means and standard deviations (SDs) of parameters that influence refractive outcomes were taken or derived from the published literature to the extent available. To evaluate their influence on refraction, thick-lens ray tracing that a...

We reviewed the SRK-II method and introduce a new equation to calculate the intraocular lens (IOL) power for eyes which underwent laser phototherapeutic keratectomy (PTK). The Gullstrand series was used to determine the power and the radius of curvature of planoconvex IOLs which alter the focal point from the cornea to reach the conjugate point on the retina. The radius of anterior corneal curv...

A prospective series of 25 eyes received an intraocular lens (IOL) of power calculated for planned ametropia, by means of the formulae of R. D. Binkhorst, from data of axial length, corneal curvature, and postoperative anterior chamber depth. All the postoperative refractions were within the +/- 2 D range from the predicted refraction, confirming the clinical value of such calculation. A retros...

Cataract surgery is evolving more and more into a refractive procedure with high expectations in terms of visual rehabilitation. Especially patients presenting after previous Excimer laser corneal surgery are used to being independent from glasses. Unfortunately, some of these patients showed unexpected hyperopic surprises after cataract surgery in the past. The changes of corneal radii and ker...

PURPOSE To determine the accuracy of a method of calculating intraocular lens (IOL) power after corneal refractive surgery. SETTING Department of Ophthalmology, Hospital de Gipuzkoa, San Sebastián, Spain. METHODS The SRK/T formula was modified to use the pre refractive surgery K-value (Kpre) for the effective lens position (ELP) calculation and the post refractive surgery K-value (Kpost) fo...

OBJECTIVE Revision of methods for estimating corneal power (Kpost) and effective lens position (ELP) for cataract surgery after corneal refractive surgery. METHODS Review of medical literature. RESULTS To calculate the intraocular lens that achieves emetropia after corneal refractive surgery it is necessary to correct the Kpost and to estimate the effective lens position again correcting it...

When a triple procedure is planned, calculation of the intraocular lens becomes a problem. Postoperative corneal power bears no relation to preoperative power, and the axial length of the globe also changes. A prospective study of 24 keratoplasties revealed a close relationship between postoperative corneal power and donor corneal power. Changes in axial length were found to be too small to pro...