Sagittal height differences of frequent replacement silicone hydrogel contact lenses

Purpose: This study aims to evaluate the sagittal height differences among a selection of commercially available monthly or two weekly replacement silicone hydrogel soft lenses. Methods: The sagittal height (CL-SAG) of four frequent replacement silicone hydrogel lenses (lotrafilcon B, balafilcon A, comfilcon A and senofilcon A) was measured for all base curve radius manufactured in spherical (-3.00 D and +3.00 D) and toric (=C -0.75 x 180 degrees) designs (11 spherical and 8 toric lenses in total). Two different lenses of each lens type were evaluated (the intra CL-SAG) using the SHSOphthalmic omniSpect by Optocraft. Results: The intra CL-SAG difference (the difference between two identical lenses from the same batch) was 11 perpendicular to SD 2 mu m. The CL-SAG of all minus lenses ranged from 3454 to 3765 mu m (an inter CL-SAG difference of 311 mu m), while the plus spherical lenses ranged from 3493 to 3757 mu m (inter CL-SAG difference 264 mu m). In the toric lens group, the range in toric minus lenses was 3495-3953 mu m (inter CL-SAG difference 458 mu m) and 3493-3980 mu m in the plus group (inter CL-SAG difference 487 mu m). The inter CL-SAG difference between the spherical and the toric lenses was statistically significant (p = 0.03). Conclusion: Marked differences in sagittal height among different commercially available frequent replacement silicone hydrogel lenses exist. Different lenses with the same package base curve value had marked differences in CL-SAG, with potential clinical significance on-eye in terms of lens behavior. The inter CL-SAG variance in the spherical lens group was smaller than in the toric lens group.