Einfluss von Kochsalzlösungen auf weiche Kontaktlinsen

Purpose: The aim was to analyze the pH value and refractive index of various saline solutions and tap water. Additionally, the study examined their impact on the design parameters base curve (BC), diameter (DIA) and central thickness (CT) of soft contact lenses. Material and Methods: pH values and refractive indices were measured using a pH-meter and refractometer. The design parameters of n = 15 lenses per material group were assessed via OCT: immediately after removal from the blister solution, after 24 hours of storage in a self-prepared saline solution and after an additional 24 hours in one of four commercial solutions or tap water. Results: Commercial saline solutions showed minor differences in pH (± 0.622) and refractive index (± 0.0008). The Oté Pharma Sol B.V. solution had the lowest pH (6.477). The greatest changes occurred in Etafilcon A (Material Group 4) in the Bausch + Lomb solution, with increased DIA by 0.753 ± 0.03 mm and BC by 0.495 ± 0.08 mm. In tap water the DIA increased by 1.465 ± 0.035 mm and the BC by 1.091 ± 0.87 mm. Other materials (Polymacon, Nefilcon A, Balafilcon A, Lotrafilcon B, Somofilcon A) remained within the ISO tolerance limits (± 0.2 mm). Conclusion: The study reveals variations in pH values and corresponding changes in DIA and BC, particularly in material group 4 with the Bausch + Lomb solution and tap water. An influence of the pH value is suspected, but further investigations are required.