Accuracy of astigmatism measurements derived from Schiempflug imaging regarding corneal front and back surface power for toric introcular lens calculation

Session Details

Session Title: Pseudophakic IOLs: Toric I

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

Paper Time: 16:30

Venue: Hall C2

First Author: : D.Park SOUTH KOREA

Co Author(s): :    R. Hwang   J. Hyun   J. Han   D. Lim   T. Chung        

Abstract Details

Purpose:

To evaluate the accuracy of preoperative corneal astigmatism using Scheimpflug imaging by comparing the estimated preoperative corneal astigmatism derived from postoperative residual astigmatism

Setting:

Samsung medical center, Seoul, South Korea, retrospective study

Methods:

Phacoemulsification with toric Precizon intraocular lens (IOL) implantation were performed in 40 eyes with corneal astigmatism from 1 diopter (D) to 5 D. Preoperative Schiempflug-measured corneal astigmatisms were obtained including simulated K (SimK) and astigmatism values regarding corneal front and back power (Pentacam Vector (Vector, derived by manual vector analysis), wavefront analysis power (WFA), true net power (TNP) and total corneal refractive power (TCRP) in 4 & 8 mm zone). At 3 months postoperatively, estimated preoperative corneal astigmatism was determined by subtracting vectors including postoperative manifest cylinder, IOL cylinder power, and individual SIA, and compared with preoperative Schiempflug-measured corneal astigmatisms.

Results:

The SIA averaged 0.45 D @74˚. The estimated preoperative corneal astigmatism did not show a statistically significant difference from preoperative corneal astigmatism values of PentacamⓇ (p=0.798), and displayed an good correlation between them with this order (Vector (r2=0.807) > WFA 4 mm (r2=0.781) > TCRP 4 mm (r2=0.725) > SimK (r2=0.722) TNP 4 mm (r2=0.720), all p<0.05), while a poor agreement in TCRP 8 mm (r2=0.436, p=0.070) and TNP 8 mm (r2=0.526, p=0.025).

Conclusions:

The values of corneal astigmatism derived from Schiempflug device’s true corneal central corneal power appear to be accurate tools for determining toric IOL cylinder power.

Financial Disclosure:

NONE