Evaluation Of Discrimination Formula For Keratoconus Using Optical Biometer

Published 2024 - 42nd Congress of the ESCRS

Reference: PO823 | Type: Free paper | DOI: 10.82333/6b83-9t07

Authors: Takashi Kojima* ¹ , Tomoya Nishida ² , Naoki Isogai ² , Akeno Tamaoki ³ , Ayako Sawaki ³ , Tomoaki Nakamura ²

¹Ophthalmology,Nagoya Eye Clinic,Nagoya,Japan;Ophthalmology,Japanese Community Healthcare Organization Chukyo Hospital,Nagoya,Japan, ²Ophthalmology,Nagoya Eye Clinic,Nagoya,Japan, ³Ophthalmology,Japanese Community Healthcare Organization Chukyo Hospital,Nagoya,Japan

Purpose

It has been reported that keratoconus can cause a significant hyperopic refractive error after cataract surgery, depending on the intraocular lens (IOL) power calculation formula. Therefore, it is important to select an appropriate IOL calculation formula. This study aimed to create a discrimination formula for keratoconus using parameters measured by an optical biometer with a corneal topographer function (OA-2000, TOMEY, Nagoyam, Japan) and to evaluate its accuracy.

Setting

Nagoya Eye Clinic, Nagoya, Japan

Methods

One hundred and eight eyes of 108 keratoconus patients (mean age 54.8 ± 16.1 years) and 90 eyes of 90 normal subjects (mean age 53.9 ± 19.2 years) were included. Initially, logistic regression analysis was performed with 60 randomly assigned stage 1 keratoconus eyes and 60 normal eyes to identify explanatory variables and develop prediction equations for discriminating keratoconus. The variables used in the analysis were age, axial length, corneal eccentricity index (CEI), and Fourier analysis components of 3.0 mm and 5.5 mm diameter. Parameters other than age were measured using the OA-2000 optical biometer. The remaining cases served as the validation group to evaluate prediction equation accuracy.

Results

The regular astigmatic and asymmetric components at 5.5 mm of the Fourier analysis were selected as explanatory variables. The AUROC was 0.998, and the sensitivity of the validation group, determined using the prediction equation created, with a cutoff value identified by the Youden index, was 94.7%, with a specificity of 100%.

Conclusions

Corneal topographer parameters equipped in the OA-2000 optical biometer allow for screening for keratoconus with high accuracy, and may be useful in selecting appropriate IOL calculation formulas and IOL selection.