Posters

Keratoconus and biometry

Poster Details

First Author: J. Bourges FRANCE

Co Author(s):                        

Abstract Details

Purpose:

to test the accuracy of different combination of biometric formula and keratometry on stage 3 keratoconus (KC3)

Setting:

Hotel-Dieu Cochin, Hopitaux Universitaires Paris Centre

Methods:

Different biometric calculations were applied to consecutive KC3 operated on for cataract surgery with IOL. The calculated IOL power (cP) targeted a -3 D postoperative refraction, using either SRK-II, SRK-T or Haigis formula, combined with different type of keratometry: from the keratometer in 4.5mm OZ (Km), SimK from the Pentacam Oculus topograph (SimK) and the 65% equivalent K Readings from its software (65%EKR). The actual power (aP) of the implanted IOL and the postoperative ametropia were collected. The ideal IOL power (iP) was iP=aP + (postop-targeted) ametropia. The lowest mean refractive error (LMRE) read as LMRE= iP-cP.

Results:

Data from 10 KC3 were analyzed. The cP were closest to iP when combining SRKII with Km (LMRE= -0.82 D; from +1.00 to -3.50), SRK-T with SimK (LMRE= -0.60; from +2.00 to -3.17) and Haigis formula with 65% EKR (LMRE=-0.11 D; from +2.00 to -3.00) respectively.

Conclusions:

Usual Biometric methods remain poorly accurate at predicting postoperative refraction in KC3 patients. The choice of keratometric data seem more decisive in lowering postoperative refractive error than biometric formulas in KC3.

Financial Disclosure:

NONE