Comparison of Methods Used to Prevent Fogging of a Non-contact Wide-field Viewing System during Vitrectomy

Purpose: To compare the effectiveness of warm saline and anti-fog solution for preventing fogging of a non-contact wide-field viewing system during vitrectomy.Methods: Five liters of water at 36 degrees C were placed in a transparent container. The fogging areas of wide-field lenses were microscopically measured. We created three groups: lenses soaked in normal saline at 25 degrees C for 1 minute (control), lenses soaked in normal saline at 50 degrees C for 1 minute (warm saline), and lenses that were wiped with a sponge soaked in anti-fog solution (ULTRASTOP pro med. Solution, Sigmapharm, Vienna, Austria) after prior soaking in normal saline at 25 degrees C for 1 minute (anti-fog). Images of fogged areas were acquired at 10 seconds and 1, 3, and 5 minutes. Extent of fogged areas and central lens invasion were determined. All experiments were repeated 10 times.Results: In the control group, the entire areas were always completely fogged. The average fog coverage values were 4.34 +/- 1.28, 6.30 +/- 1.38, 56.00 +/- 25.01, and 93.81 +/- 5.88% at 10 seconds and 1, 3, and 5 minutes in the warm saline group and 4.74 +/- 0.57, 7.35 +/- 0.96, 10.13 +/- 1.09, and 11.74 +/- 1.74% in the anti-fog group, respectively. There were significant differences at 3 and 5 minutes (p = 0.029, p = 0.012). Fogging of the central lens was detected in 8 tests after 3 minutes and all 10 tests after 5 mi-nutes in the warm saline group, but no fogging was detected in the anti-fog group.Conclusions: Application of an anti-fog solution to a wide-field viewing lens prevents lens fogging during vitrectomy.