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Grayson A. Roumeliotis, Cindy M. Hutnik; A Simple, Reproducible, And Cost Effective Axis Marking System For Toric Lens Implantation. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4732.
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© ARVO (1962-2015); The Authors (2016-present)
Proper positioning of TORIC intraocular lenses (IOLs) depends upon pre-operative determination of the axis of astigmatism. We sought to validate a new pre-operative axis marking system for toric intraocular lens (IOL) implantation. We hypothesize that our method will provide accurate axis markings, while reducing costs and increasing operating room efficiency.
We added a calibrated decal to a Haag-Streit slitlamp so we could accurately set the slit at any angle, 0-180º. Typically, the axis for the insertion of the toric IOL is calculated using pre-operative keratometry and biometry. Arbitrary axes were set in our test models. To mark a selected axis on the eye, the slit-beam was positioned so that one end abutted the visual axis, and the other fell on the corneal limbus. With the slit-beam set to the desired angle, it was used to guide a linear superficial epithelial abrasion using a 30-gauge needle at the corneal limbus. For validation purposes, the horizontal axis was marked in the same way. We assessed the accuracy of this technique in two ways: A masked independent observer, blinded to the intended axis, was asked to find the superficial mark and to determine the axis using only the calibrated slit-lamp. We also compared the axis markings made with our method to a currently used intra-operative axis marker (beveled degree gauge, ASICO®).
The average error between measurements set by the marker and those estimated by the independent observer was 3.2º (SD= 2.6º). When angles set with the calibrated slitlamp were assessed using the protractor, there was no difference between the intended and the measured axis.
The technique outlined can accurately mark the axis for TORIC IOL implantation. It also obviates the need for sterile instrument sets for pre- and intra-operative marking. The technique is thus a simple, adaptable, inexpensive, and accurate method for surgeons interested in offering TORIC IOL technology to their patients.
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