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Shinichiro Nakano, Takahiro Hiraoka, Tetsuro Oshika; Comparison of predicted refractive outcomes between different methods of toric IOL calculating methods. Invest. Ophthalmol. Vis. Sci. 2019;60(9):498.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the effectiveness between two different methods for toric intraocular lens (T-IOL) calculation, one based on measurement of both anterior and posterior corneal astigmatism measurement by anterior segment optical coherence tomography (AS-OCT) and the other based on predicted posterior corneal astigmatism formula (Barret toric calculator).
Thirty-five consecutive cases of twenty-seven patients (10Male 16Female; mean age77.2 ± 3.5 years old) with corneal astigmatism over 0.75diopters(D) (mean 1.45±0.57D) which underwent cataract surgery with T-IOL implantation were studied retrospectively. Postoperative expected residual astigmatism was calculated by IOL makers website T- IOL calculator, using AS-OCT (CASIA, TOMEY) measured anterior and posterior corneal refractive power (realpower)as the keratometry input (AS-OCT realpower method). Surgery induced astigmatic error (SIA error) was calculated by subtracting postoperative expected residual astigmatism from the postoperative refractive results. The postoperative expected residual astigmatism of Barret toric calculator was calculated by using anterior corneal refractive power of AS-OCT as the keratometry input. Adding SIA error to this, simulated postoperative residual astigmatism of T-IOL implant by Barret toric calculator was calculated (simulated Barret method). Vector analysis was performed between residual astigmatic results of the AS-OCT realpower method and that of the simulated Barret calculator method.
Both AS-OCT realpower method and simulated Barret method significantly reduced the preoperative astigmatism (P<.0001). The absolute postoperative residual astigmatism for AS-OCT realpower method and simulated Barret method were 0.96±0.71 and 0.97±0.53D, respectively. There was no significant difference between two methods (P=0.74). The centroid of postoperative residual astigmatism was slightly oblique (35.1degrees) with AS-OCT realpower method with the magnitude of 0.51 D, while simulated Barret method had the against-the-rule astigmatism (27.8degrees) with the magnitude of 0.82 D respectively. There was no significant difference between two methods (P =0.64).
T-IOL calculation based on measurement of both anterior and posterior corneal astigmatism by AS-OCT and predicted posterior astigmatism by Barret toric calculator had the same amount of effectiveness in postoperative astigmatic correction.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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