Evaluation of astigmatism calculation with Barrett formula by using three different devices

Session Details

Session Title: Toric IOL Calculations & Alignment

Session Date/Time: Sunday 23/09/2018 | 08:00-10:00

Paper Time: 08:30

Venue: Room A5

First Author: : X.Chen CHINA

Co Author(s): :                        

Abstract Details

Purpose:

To compare the astigmatism calculation with Barrett formula by using a swept source fourier domain OCT (CASIA SS-1000), a Scheimpflug tomographer (Oculus Pentacam) and an optical biometry (Zeiss IOLmaster 500). To investigate the prediction astigmatism value errors with Barrett formula by using three different devices and actual corneal refractive power.

Setting:

Xu Chen, Kunqian Wei, Fei Qian. Shanghai Aier Eye Hospital, Shanghai, China

Methods:

Measured astigmatism included K-readings from IOLmaster (KIOLmaster), SimKPentacam, true net power (TNPPentacam), total corneal refractive power(TCRPPentacam) from Pentacam and Keratometric reading (KCASIA) and Real Keratometric (Real KCASIA) readings from CASIA were obtained. The astigmatism axis was also recorded. Calculated astigmatism value and axis were assessed by Barrett online calculator with KIOLmaster, SimKPentacam, TNPPentacam, KCASIA. Prediction difference between the calculated astigmatism and TCRPPentacam were analyzed with centroid method.

Results:

The centroid of the refractive astigmatism of KIOLmaster，SimKPentacam and KCASIA was 0.38±0.14@179.70, 0.16±0.14@89.85, 0.12±0.12@89.99, astigmatism with Barrett calculator was 0.14±0.14@179.38, 0.08±0.13@0.20, 0.16±0.13@179.62. TNPPentacam, TCRPPentacam and Real KCASIA were 0.29±0.16@90.12, 0.26±0.17@90.03, 0.16±0.14@0.07. All calculated astigmatism was decreased by using Barrett calculator, similar to centroid value of Real KCASIA. Similar changes were observed in WTR group, while TNPPentacam, TCRPPentacam, Real KCASIA were 0.29±0.16@90.12, 0.26±0.17@90.03, 0.16±0.14@0.07 are higher than Barrett calculated values. But in ATR group, the centroid changes after Barrett calculator are no consistency. The same results were observed in comparison of calculated astigmatism and TNPPentacam, TCRPPentacam, Real KCASIA.

Conclusions:

The centroid of the refractive astigmatism is decreased by using Barrett online calculator, especially in with-the-rule astigmatism patients. But in ATR group, the relationship of calculated refractive astigmatism results and TNPPentacam, TCRPPentacam, Real KCASIA should be further investigate.

Financial Disclosure:

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