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Linda Tsai, Sanjeev Kasthurirangan, Jennifer Depew, Pamela Smith, Kristen Featherstone; Clinical Correlates of Multifocal Defocus Curve. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3122. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The depth of focus profile of multifocal intraocular lenses (IOLs) is evaluated through defocus curves i.e. visual acuity (VA) measured through trial lenses. Depth of focus (in diopers) from defocus curves is calculated to define the benefit provided by a multifocal IOL. It is unclear how defocus curve measurements correspond to other clinical measures of near performance. The purpose of this study is to evaluate the correspondence between measures of near VA at real distance to the VA and depth of focus measured through defocus curves for diffractive multifocal IOLs.
In a prospective, multicenter, bilateral, evaluator-masked, clinical study, subjects with bilateral cataracts were included for bilateral IOL implantation with multifocal TECNIS IOL model ZKB00 (+2.75 D ADD), multifocal TECNIS IOL model ZLB00 (+3.25 D ADD) or the monofocal control model ZCB00. At 6-month postoperative time point a subgroup of subjects (n = 61 ZCB00, n = 59 ZKB00, n = 63 ZLB00) underwent defocus testing (from +1.0D to -4.0D in 0.5D steps) along with standard ophthalmic testing including best corrected distance VA (BCDVA) and distance corrected near VA (DNCVA) at 40 cm. Regression analysis was performed for i) distance and near VAs compared to the 0.0D and -2.5D VA from defocus curve and ii) distance corrected near VA compared to the depth of focus calculated for a threshold VA of 20/40.
Average defocus curves showed maximum VA only at 0.0D for the monofocal ZCB00 IOL compared to two peaks at 0.0D and -2.0D for the multifocal ZKB00 IOL and 0.0D and -2.5D for the multifocal ZLB00 IOL. Correlation of direct vs. defocus measured VA for IOL groups combined showed high correlation (direct VA = +0.008 + 0.85*defocus VA, r = 0.89), however the slope of 0.85, indicates lower (i.e. worse) VAs measured in the defocus test compared to direct measure of VA. Correlation of direct near VA vs. depth of focus showed high correlation (near VA = +0.66 – 0.162*depth of focus, r = 0.777), indicating 1.6 line VA improvement with one diopter of calculated depth of focus.
Slightly lower visual acuities were measured in a defocus test compared to real distances for corresponding vergence demands. Depth of focus calculated from defocus test was predictive of near performance of multifocal IOLs.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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