The effects of eye drops on corneal thickness in adult myopia

Purpose: To study the effects of Complex Tropicamide (0.5% Tropicamide and 0.5% phenylephrine HCI) and Saline solution on corneal thickness in adult myopic patients with the Orbscan II system. Setting: Department of Ophthalmology, Yantai Yuhuangding Hospital. Design: Prospective, nonrandomized, clinical trial. Methods: The thinnest pachymetry of the cornea was obtained before and 1.5 hours after administration of three drops of Complex Tropicamide to the left eyes of 58 patients (58 eyes) and Saline solution to their 31 right eyes, respectively. The corneal thickness of the other 27 right eyes before and 1.5 hours after eyelid closure without exposure to eye drops was used as the control group. Results: The thinnest pachymetry of the cornea was significantly higher after exposure to eye drops in the Tropicamide group (23.36 +/- 15.01 mu m; t = - 11.855, P < 0.001). Similar findings were also noted in the Saline group (7.13 +/- 8.11 mu m, t = -4.894, P < 0.001). The difference between the two groups was also significant (t = 6.737, P < 0.001). There were no statistically changes in corneal thickness in control group. The drops tested have no effect on the location of the thinnest corneal site and its distance form the visual axis. Conclusion: Eye drops including Saline solutions may have significant effects on the corneal thickness in myopia, and this may have implications for corneal refractive surgery.