الفهرس 
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Abstract
Recent applications and developments have increased the accuracy of preoperative corneal shape and refractive power evaluations prior to phacoemulsification with intraocular lens (IOL) implantation. The toric IOL has been shown to have substantial efficacy in correcting astigmatism. Accurate keratometry values (K-values) can be used as part of surgical planning for corneal incision design, astigmatic keratotomy (AK), the management of surgery-induced astigmatism (SIA), and correcting postoperative residual astigmatism. Several previous studies have compared corneal astigmatism measurements obtained using a range of keratometers.
The VERION image-guided system (Alcon, Fort Worth, TX, USA) is a new surgical-assisted platform that combines the use of the VERION Reference Unit and enables the measurement of K-values. Preoperative corneal curvature data can be integrated with anterior segment imaging for intraoperative registration.
Our study was a cross-sectional study conducted on Ophthalmology Department, Ain Shams University Hospital. We measured the correlation coefficient for the keratometric measurements of VERION Image Guided System, an optical biometry (IOLmaster) and corneal topography in Egyptian cataractous patients
This study included 45 patients in the period from 2020 to 2021 the males were (51.1%) with age ranged from 24 to 92 years with mean±SD of 67.53±10.92 years.
Mean±SD for K1 was (43.06 ± 2.03, 43.27 ± 2.07and 43.45 ±2.01), K2 was (44.48 ± 2.02, 44.84 ± 2.16 and 44.99 ± 2.12), Astigmatism was (1.42 ± 0.75,1.57 ± 0.74 and 1.53 ± 0.75), Km (43.81 ± 1.99,44.05 ± 2.08 and44.15 ±2.06) and for flat axis was (71.05 ± 52.96, 62.87 ± 48.99 and 83.53 ±53.16) for Keratograph, IOLmaster and VERION Image Guided system respectively. There was no statistically significant difference found between the three studied devices regarding K1, K2, AST, Km and Flat axis
There were excellent correlations between the Keratograph and each of VERION and IOLmaster for the Km values, good correlation was found for the axis and Astigmatism between Keratograph and VERION, and moderate correlation was present for axis and Astigmatism between Keratograph and IOLmaster.
The interdevice differences in Axis, Km, and the magnitude of astigmatism measurements for ”VERION and Keratograph ”, was (12.4867± 61.744, 0.3469 ±0.8834 and 0.1149± 0.600) respectively and for IOLmaster and Keratograph was (-8.18± 30.181, 0.2491± 0.5112 and 0.1533 ± 0.5576) respectively
The agreement of keratometry measurements (axis, Km and astigmatism) obtained from VERION vs Keratograph as (-108.5315-133.5048, -1.3845-2.0783 and -1.0616-1.2913) respectively and IOLmaster vs Keratograph are (-67.3347-50.9747,-0.7528-1.2510 and -0.9396-1.2463) respectively.