Background: It is important to obtain precise pre-operative measurement of pre-existing corneal astigmatism in cataract
surgery with toric intraocular lens (IOL) implantation. There have been reports of irregular corneal surface and topographic patterns in dry eye patients which have affected the corneal parameters in some corneal measurement devices.
Objective: To investigate the effect of dry eye and artificial tears on parameters associated with corneal curvature, corneal astigmatism, recommended IOL placement axis, recommended IOL spherical power, recommended IOL cylindrical power and calculated residual astigmatism measured by VERIONTM Image Guided System in subjects who planned to undergo cataract surgery with toric IOL implantation.
Material and Method: This was a prospective, quasi-experimental study. All subjects were classified into a non-dry eye anda dry eye group. All parameters were obtained using VERIONTM at baseline, and 5 and 30 minutes after artificial tear instillation, and all measurements were analyzed using repeated measures ANOVA.
Results: Seventy eyes of 35 subjects were included in this study. Twenty-eight 28 (40.0%) eyes were classified as dry eye level 1, 19 (27.1%) as level 2, 8 (11.4%) as level 3, 1 (1.4%) as level 4, and 14 (20.0%) eyes were non-dry eye. In subgroup analysis, there were no statistically significant differences in the mean corneal curvature, amount of refractive cylinder, recommended IOL placement axis, recommended IOL spherical power, recommended IOL cylindrical power between baseline and 5 and 30 minutes after artificial tear instillation in all subgroups (p>0.05). There was a statistically significant difference in calculated residual astigmatism between baseline and 30 minutes inthe dry eye level 2 subgroup (p = 0.012).
Conclusion: The accuracy of measurement by VERIONTM may be affected by dry eye disease, especially in cases higher than level 2. Accurate corneal parameters must be obtained in order to calculate the correct IOL placement axis, and toric IOL spherical and cylindrical power.

Keywords: Dry eye, Cataract surgery, Phacoemulsification, Toric intraocular lens, Corneal curvature, Keratometry, Corneal astigmatism, IOL calculation, VERIONTM image-guided system