Lisbon 2017 Delegate Registration Programme Exhibition Virtual Exhibition Satellites OneWorld Travel Discount
escrs app advert

Optimized keratometry and total corneal astigmatism for toric intraocular lens calculation

Search Title by author or title

Session Details

Session Title: Presented Poster Session: Cataract Surgery Outcomes

Venue: Poster Village: Pod 1

First Author: : K.Næser DENMARK

Co Author(s): :    G. Savini              

Abstract Details

Purpose:

To identify the most accurate modality of keratometric astigmatism (KA) or total corneal astigmatism (TCA) for toric intraocular lenses (T-IOLs) calculation and to optimize corneal measurements in order to eliminate the residual refractive astigmatism.

Setting:

G.B. Bietti Foundation IRCCS, Rome, Italy

Methods:

We consecutively enrolled 64 eyes with a monofocal T-IOL. Preoperatively, a rotating Scheimpflug camera (Pentacam HR, Oculus) measured TCA through ray-tracing. Different combinations of measurements at 3-mm diameter, centered on the pupil or the corneal vertex, and performed along a ring or within it, were compared. KA was measured by the same Scheimpflug camera and a corneal topographer (Keratron, Optikon 2000). Astigmatism analysis was carried out with Næser’s polar value method. The optimal preoperative corneal astigmatism was back-calculated from the postoperative refractive astigmatism.

Results:

With both devices, KA overcorrected with-the-rule (WTR) astigmatism by 0.6 diopters (D) and undercorrected against-the-rule (ATR) astigmatism by 0.3 D. The lowest meridional error in refractive astigmatism (ERA) was achieved by the TCA pupil/zone measurement in WTR eyes (0.27 D overcorrection) and TCA apex/zone measurement in ATR eyes (0.07 D undercorrection). In the whole sample, no measurement allowed more than 43.75% of eyes to yield an absolute error in astigmatism power <0.5 D. Optimized astigmatism values increased the percentage of eyes with this error up to 57.81%, with no difference with respect to Barrett’s and Abulafia-Koch’s calculators.

Conclusions:

Compared to KA, TCA improves calculations for T-IOLs, but optimization of corneal astigmatism leads to the most accurate results.

Financial Disclosure:

-

Back to previous