Comparison of predicted refractive outcomes between two different toric IOL calculation methods

Session Details

Session Title: Presented Poster Session: Toric IOLs

Venue: Poster Village: Pod 1

First Author: : S.Nakano JAPAN

Co Author(s): :    T. Hiraoka   T. Oshika                    

Abstract Details

Purpose:

To compare the accuracy 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).

Setting:

In Ryugasaki Saiseikai Hospital, Ibaraki, Japan Fifty-eight consecutive eyes of thirty-eight patients (20 Male, 18 Female; mean age 77.0 ± 5.7 years old) with corneal astigmatism over 0.75 diopters (D) (mean 1.60 ± 0.80 D) who underwent cataract surgery with T-IOL implantation were studied retrospectively.

Methods:

Postoperative expected residual astigmatism was calculated by T-IOL calculator of IOL makers website, using AS-OCT (CASIA, TOMEY) measured anterior and posterior corneal refractive power (realpower) as 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 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 both methods.

Results:

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 0.84 ± 0.35 and 0.86 ± 0.32 D, respectively. There was no significant difference between two methods (P =0.44). The centroid of postoperative residual astigmatism was oblique (41.4 degrees) with AS-OCT realpower method with the magnitude of 0.42 D, while simulated Barret method had the against-the-rule astigmatism (28.8 degrees) with the magnitude of 0.74 D, respectively.

Conclusions:

In postoperative astigmatic correction, the accuracy of T-IOL calculation based on measurement of both anterior and posterior corneal astigmatism by AS-OCT was equivalent to that based on predicted posterior astigmatism by Barret toric calculator.

Financial Disclosure:

None