Variation in sag values in daily disposable, reusable and toric soft contact lenses

Published:January 08, 2021DOI:



      While knowledge of the ocular surface sagittal height (OC-SAG) is increasing with newer instrumentation, understanding of soft lens sag values (CL-SAG) in daily clinical practice is limited. This study aimed to report the differences in CL-SAG of a large collection of daily disposable (DD), reusable (2-week and 4-week replacement) and toric lens designs.


      12 different spherical DD and 15 reusable lens types were analysed (labelled power −3.00D); 17 different toric lens types analysed (6 DD and 11 reusable) in −3.00D =C 0.75 × 180. Posterior CL-SAG was measured directly using a spectral domain OCT-based instrument (Optimec is830).


      The range in CL-SAG for DDs was 3,398-3,912 microns, for reusable lenses 3,372-4,004 microns and for toric lenses 3,536-4,157 microns. Lens diameter and BC together influence CL-SAG values. For lenses with the same labelled base curve (BC), the maximum difference in the DD group was 264 microns, in the reusable group 418 microns and in the toric group 345 microns. Three lens designs within the DD group and five in the reusable group offer two BCs, with an average variation (±SD) in CL-SAG of 276 ± 39 microns; one toric lens with two BCs showed a 377-micron difference.


      Marked differences in CL-SAG values were found in this study, also between lenses of the same BC. While ECPs should be aware that diameter and BC together influence CL-SAG, this also indicates that lens substitution based on BC alone could result in substantial differences in CL-SAG, with a potential impact on lens fit. Lens designs offering two BCs showed a somewhat narrow band in absolute terms in CL-SAG, and switching from a spherical to a toric lens of the same lens manufacturer could result in a significant change in CL-SAG.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Contact Lens and Anterior Eye
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Wichterle O.
        • Lím D.
        Hydrophilic gels for biological use.
        Nature. 1960; 185: 117-118
        • Pearson R.
        A review of the limitations of the first hydrogel contact lens.
        Clin Exp Optom. 2010; 93: 15-25
      1. (Accessed Aug 4 2020).

        • Bibby M.
        Sagittal depth considerations in the selection of the base curve radius of a soft contact lens.
        Am J Optom Physiol Opt. 1979; 56: 407-413
        • van der Worp E.
        • Wolffsohn J.
        • Jones L.
        When was the last time you fitted a soft lens?.
        Cont Lens Anterior Eye. 2020; 43: 415-417
        • Hall L.
        • Hunt C.
        • Young G.
        • Wolffsohn J.
        Factors affecting corneoscleral topography.
        Invest Ophthalmol Vis Sci. 2013; 54: 3691-3701
        • van der Worp E.
        • Caroline P.
        • Hall L.
        On a higher level – position paper on terminology regarding anterior ocular surface topography.
        Global Contact. 2015; 68: 22-24
        • Giovanzana S.
        • Ţălu Ş.
        • Nicoară S.D.
        Sagittal height differences of disposable soft contact lenses.
        Int Ophthalmol. 2020; 40: 459-465
        • van der Worp E.
        • Mertz C.
        Sagittal height differences of frequent replacement silicone hydrogel contact lenses.
        Cont Lens Anterior Eye. 2015; 38: 157-162
        • Stapleton F.
        • Tan J.
        Impact of contact lens material, design, and fitting on discomfort.
        Eye Contact Lens. 2017; 43: 32-39
        • Hall L.A.
        • Hunt C.
        • Young G.
        • Wolffsohn J.
        Factors affecting corneoscleral topography.
        Invest Ophthalmol Vis Sci. 2013; 54: 3691-3701
        • Ritzmann M.
        • Caroline P.
        • Börret R.
        • Korszen E.
        An analysis of anterior scleral shape and its role in the design and fitting of scleral contact lenses.
        Cont Lens Anterior Eye. 2018; 41: 205-213
        • Consejo A.
        • Llorens-Quintana C.
        • Bartuzel M.
        • Iskander D.
        • Rozema J.
        Rotation asymmetry of the human sclera.
        Acta Ophthalmol. 2019; 97: 266-270
        • DeNaeyer G.
        • Sanders D.
        • van der Worp E.
        • Jedlicka J.
        • Michaud L.
        • Morrison S.
        Qualitative assessment of scleral shape patterns using a new wide field ocular surface elevation topographer.
        J Cont Lens Res Sci. 2020; 4: 12-22
        • Coldrick B.
        • Richards C.
        • Sugden K.
        • Wolffsohn J.
        • Drew T.
        Developments in contact lens measurement: a comparative study of industry standard geometric inspection and optical coherence tomography.
        Cont Lens Anterior Eye. 2016; 39: 270-276
        • Sorbara L.
        • Maram J.
        • Fonn D.
        • Woods C.
        • Simpson T.
        Metrics of the normal cornea: anterior segment imaging with the Visante OCT.
        Clin Exp Optom. 2010; 93: 150-156
        • Young G.
        • Potts M.
        • Sulley A.
        The effect of temperature on soft contact lens diameter.
        Eye Contact Lens. 2016; 42: 298-302
        • Wolffsohn J.
        • Hunt O.
        • Basra A.
        Simplified recording of soft contact lens fit.
        Cont Lens Anterior Eye. 2009; 32: 37-42
        • Wolffsohn J.
        • Hall L.
        • Mroczkowska S.
        • Hunt O.
        • Bilkhu P.
        • Drew T.
        • et al.
        Cont Lens Anterior Eye. 2015; 38: 339-344
        • Young G.
        • Hall L.
        • Sulley A.
        • Osborn-Lorenz K.
        • Wolffsohn J.
        Inter-relationship of soft contact lens diameter, base curve radius, and fit.
        Optom Vis Sci. 2017; 94: 458-465
        • Sulley A.
        • Osborn Lorenz K.
        • Wolffsohn J.
        • Young G.
        Theoretical fitting characteristics of typical soft contact lens designs.
        Cont Lens Anterior Eye. 2017; 40: 248-252