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Aixa Alarcon, Carmen Canovas, Robert Rosen, Henk A Weeber, Linda Tsai, Kendra Hileman, Patricia A Piers; Pre-clinical metrics to predict visual outcomes in the intermediate range for pseudophakic patients. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2976. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the clinical visual performance in the intermediate range measured in patients implanted with different IOL models to optical bench testing on the same IOLs to determine an optical metric capable of predicting intermediate vision.
Through focus modulation transfer function (MTF) for different spatial frequencies and US Air Force (USAF) pictures for a 3mm pupil in white light were measured using an optical bench for an aspheric monofocal IOL, three multifocal IOLs (MFIOLs) with different add powers (2.75, 3.25 and 4D) and an extended range of vision IOL. Pre-clinical metrics, such as the area under the MTF (MTFa) for multiple spatial frequencies and the cross correlation coefficient (CCC) based on USAF pictures were calculated for each defocus position from -0.5D to -2D in 0.5D steps. Additionally, the area under the MTFa (AU MTFa) over the intermediate defocus range was computed for each IOL. Each pre-clinical metric was compared to the defocus curves measured in patients bilaterally implanted with the same IOL. In all cases, high contrast defocus VA was measured binocularly using the ETDRS chart with best distance correction.
MTFa from 0 to 50cpmm and CCC showed very good correlation with the decimal VA measured at each defocus position in the intermediate range (r = 0.89 for both metrics). The average intermediate visual performance, calculated as the area under defocus curves was highly correlated (r= 0.81) with the AU MTFa from 0 to 50cpmm. Both clinical and pre-clinical data show that the monofocal and the MFIOL with the highest add power had lower intermediate performance. MFIOLs with lower add powers showed better intermediate vision, while the extended range of vision IOL had the best visual performance in the intermediate range.
Intermediate visual performance in pseudophakic eyes can be predicted by optical bench testing. Pre-clinical metrics like the MTFa for multiple spatial frequencies and CCC were shown to correlate well with the VA measured clinically. The area under the clinical defocus curve estimates the mean intermediate visual performance well and is well correlated with the AU MTFa. Therefore, these pre-clinical metrics can be used to rank the intermediate visual performance of different IOL models.
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