Comparison of Sirius Corneal Topographer and Digital Callipers to Determine Corneal White-To-White Diameter in Phakic Intraocular Lens Implantation

Precise measurement of the white-to-white diameter is important for the selection of an ideal sized phakic intraocular lens. Purpose The purpose of this study was to compare the white-to-white measured using Sirius corneal topographer with that of white-to-white measured manually using digital callipers. Method A prospective observational study conducted in a refractive eye care centre from November, 2016 to April, 2017. Forty eyes of twenty patients were included in the study. The corneal white to white diameter was measured using both digital callipers and Sirius corneal topographer. Statistical analysis was performed using SPSSv20.0. Result The mean corneal diameter with the Sirius corneal topographer and the digital callipers was 12.18 mm and 11.91 mm respectively. Based on comparison done by paired t-test, corneal diameter measurements using digital callipers were 0.27 mm smaller than the measurements obtained using Sirius topography device. Conclusion The white-to-white measurement using digital callipers is lesser in comparison to the measurement using the Sirius corneal topographer. The sizing of the phakic IOL was acceptable when the measurements using digital callipers were taken, providing an optimal vault. Measuring the white-to-white diameter of the cornea using the calliper is a reliable method and prevents over or under sizing of the phakic IOL.