Is it not absolutely necessary to consider the effect of posterior corneal curvature in toric IOL calculation before it is too late?

Session Details

Session Title: Pseudophakic IOLs: Toric I

Session Date/Time: Saturday 10/09/2016 | 16:00-18:00

Paper Time: 16:42

Venue: Hall C2

First Author: : J.Agrawal INDIA

Co Author(s): :                        

Abstract Details

Purpose:

If toric IOL based on anterior corneal astigmatism(ACA) results in established over or undercorrection factor due to posterior corneal astigmatism (PCA) holds true . To establish if Baylor nomogram or recently developed co-efficient of adjustment with ACA gives satisfactory results. To compare the above methods with Barrett toric calculator. Is it absolutely necessary to advise Toric IOL in all cases of moderate regular astigmatism of around +1.00dcyl during phaco considering the effect of posterior corneal astigmatism?

Setting:

The study is conducted at my private clinic. we retrospectively evaluate the case records of different pts using one of the four different methods for calculation: while the surgeon and measuring device of corneal astigmatism ( IOL master ) remaining the same in all cases. Agrawal Eye Care, India

Methods:

In retrospective study, 46 eyes undergone phaco with toric IOL powers calculated using anterior corneal data alone. Eyes were grouped as either “with the rule” (WTR) or “against the rule” (ATR) and targeted versus achieved astigmatic outcomes were compared. In prospective study 34eyes undergone phaco using Baylor nomogram in 27 eyes; and in 7 eyes using a co-efficient of adjustment of 0.75 for WTR and 1.42 for ATR to ACA power value. In another 17 eyes, we have used Barrett toric calculator.

Results:

Significant prediction errors occurred only when ACA alone were considered; overcorrection occurred by factor 1.32 in WTR and undercorrection by factor 0.69 in ATR . Using Baylor nomogram in 27 eyes gives significant satisfactory result ; which is comparable to the result obtained in 7 eyes using correction coefficient of adjustment. The median absolute errors and centroid errors in predicted residual astigmatism were the lowest when Barrett toric calculator was used.

Conclusions:

To improve outcome, consideration of PCA is must.It is necessary to consider toric IOL in astigmatism of 0.75 of ATR and 1.25 of WTR depending on age of patients. Baylor nomogram or a coefficient of adjustment of 0.75 for WTR and 1.42 to ATR applied to achieve equally good result. The most accurate prediction of residual astigmatism was achieved with Barrett toric IOL calculation.

Financial Disclosure:

NONE