Röggla V, Leydolt C, Schartmüller D, et al. - Researchers conducted this prospective randomized cross-over, before-and-after clinical study to evaluate the influence of artificial tears of different viscosity on K-readings prior to cataract surgery. In total, 123 eyes of 80 patients prior to cataract surgery were assigned to two groups based on normal and dry eyes. Instillation of either high- or low-viscosity eye-drops was accompanied by two native baseline keratometries. After instillation, keratometry was repeated 30 seconds, 2 minutes, and 5 minutes. Tear film stabilizing eye-drops before measuring keratometry significantly influenced K-readings, particularly in dry eyes. After instillation of eye-drops, a time period of more than five minutes should be allowed to pass. The higher the eye-drop viscosity, the stronger the influence and the longer their persistence.