Sagittal height differences of frequent replacement silicone hydrogel contact lenses

• Eye care practitioners (ECP) have limited tools to choose the first trial soft lens.
• There is a weak correlation between K-readings and soft lens fit characteristics.
• The sagittal height of soft lenses (CL-SAG) is currently unavailable to ECP.
• Marked differences in CL-SAG were found in this study between lenses.
• Lenses with the same package base curve value also had marked differences in CL-SAG.

PurposeThis study aims to evaluate the sagittal height differences among a selection of commercially available monthly or two weekly replacement silicone hydrogel soft lenses.MethodsThe 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 × 180°) 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.ResultsThe intra CL-SAG difference (the difference between two identical lenses from the same batch) was 11 ± SD 2 μm. The CL-SAG of all minus lenses ranged from 3454 to 3765 μm (an inter CL-SAG difference of 311 μm), while the plus spherical lenses ranged from 3493 to 3757 μm (inter CL-SAG difference 264 μm). In the toric lens group, the range in toric minus lenses was 3495–3953 μm (inter CL-SAG difference 458 μm) and 3493–3980 μm in the plus group (inter CL-SAG difference 487 μm). The inter CL-SAG difference between the spherical and the toric lenses was statistically significant (p = 0.03).ConclusionMarked 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.