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Langis Michaud
Gabriella Courey


This study aims to determine if lens or tear fluid reservoir thicknesses (LT/FRT) may influence the presence of residual astigmatism and participant’s visual acuity.

The study was a randomized, non-dispensing, prospective study. Empirically and randomly chosen participants were fitted with 4 combinations (350 and 250 um LT fitted with 250 and 350 um FRT) of 16 mm diameter scleral lenses, designed using a corneo-scleral profiler software (sMap 3D, Visionary Optics, US). Lenses haptics were kept spherical for all lenses. They were evaluated under a slit lamp, anterior segement OCT (objective fluid reservoir and lens thicknesses), topography over lenses and aberrometry, after 30 minutes of lens wear. Spherico-cylindrical refraction and logMar acuity were also assessed.

Study population was composed of 24 participants aged 24.2 + 4.7 years old. Baseline refractive error was -2.3 + 1.6 D with -0.48 + 0.26 D of astigmatism. In vivo (OCT) lens A was 344.1 ± 15.4 um thick, fitted with a vault of 213.6 ± 42.4 um; Lens B was 346.2 ± 12.5/327.2 ± 44.8; Lens C was 260.3 ± 17.7/214.0 ± 40.6 um and Lens D was 262.2 ±13.2/330.8 ± 52.0 respectively. All lenses were found similarly decentered inferiorly by 0.10 to 0.15 um. BCVA was −0.32 + 0.08 (A), −0.21 + 0.10 (B), −0.28 + 0.08 (C), and −0.14 + 0.10 (D), compared to −0.25 + 0.08 (A), −0.11 + 0.10 (B), −0.23 + 0.06 (C), and −0.05 + 0.12 (D) when sphere only was compensated. Residual refractive astigmatism (RA = -0.50 to -0.75D) is found significantly higher based on the FRT (F=9.560; p=0.037) and not LT(F=0.429; p=0.522). There is no correlation be-tween RA and over-k readings (Lens A r=-0.078, p=0.773; Lens B r=−0.073, p=0.788; Lens C r=−0.345, p=0.171; Lend D r=0.019, p=0.944). Higher order aberrations, mostly vertical coma, were found clinically significant but not statistically different between lenses (A= 0.350 + 0.032; B=0.382 + 0.053, C=0.329 + 0.044 and D=0.385+ 0.062; p=0.776)

This study proves that low level of RA may be found when scleral lenses are fitted on normal corneas. Its occurrence is related to the presence of high-order aberrations and less likely to lens flexure.


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How to Cite
Michaud L, Courey G. INFLUENCE OF THE SCLERAL LENS AND FLUID RESERVOIR THICKNESSES ON RESIDUAL ASTIGMATISM . JCLRS [Internet]. 2021Jan.14 [cited 2021Apr.22];5(1):e1-e8. Available from:
Original Article
Author Biographies

Langis Michaud, Université de Montréal

Full professor- Université de MOntréal
Senior Optometrist
Contact Lens and Clinical researcher
Speaker for professional and public audiences
Teaching in optometry - ocular diseases
Expert on ad board committees
Legal expertise in contact lenses
Communication: radio and television on topics related to eye, vision, contact lenses, children vision development, etc.

Gabriella Courey , University of Montreal

Ecole d’optométrie de L’Université de Montréal


1. Johns L. and Barnett M. Contemporary Scleral Lenses: Theory and Application. Bentham eBooks; 2017.
2. van der Worp E, et al. Modern scleral contact lenses: A review. Cont Lens Anterior Eye 2014;37(4):240–50.
3. Goldberg JB. RGP contact lens adherence: Flexure or tear film thinning—Can we define the cause? Internat Contact Lens Clinic 1994;21(1):26–29.
4. Lin MC and Snyder C. Flexure and residual flexure with RGP lenses. Contact Lens Ant Eye 1999;26(1):5–9.
5. Corzine JC and Klein SA. Factors determining rigid contact lens flexure. Optom Vis Sci 1997;74(8):639–45.
6. Jedlicka J. Solving scleral lens complications. C.L. Spectrum 2012; 27(October):40–44.
7. Vincent SJ, et al. The influence of centre thickness on miniscleral lens flexure. Cont Lens Anterior Eye 2019;42(1):63–69.
8. Schornack M, Nau C, and Brown W. Estimation of refractive power of scleral lens/fluid reservoir optical systems in non-parallel scleral lens fits. in Poster presented at: Global Specialty Lens Symposium 2014.
9. Bray C, et al., Change in over-refraction after scleral lens settling on average corneas. Ophthalmic Physiol Opt 2017; 37(4):467–72.
10. Ramdass S, Rosen C, and Norman C. Clinical Analysis of Scleral Lenses on Regular Cornea, in Global Specialty Lens Symposium. 2016: Las Vegas.
11. Vincent SJ and Fadel D. Optical considerations for scleral contact lenses: A review. Cont Lens Anterior Eye 2019.
12. Hastings GD, et al. Comparison of wavefront-guided and best conventional scleral lenses after habituation in eyes with corneal ectasia. Optom Vis Sci 2019;96(4):238–47.
13. Michaud L, et al. Predicting estimates of oxygen transmissibility for scleral lenses. Cont Lens Anterior Eye 2012;35(6):266–71.
14. Vincent SJ, Alonso-Caneiro D, and Collins MJ. The temporal dynamics of miniscleral contact lenses: Central corneal clearance and centration. Cont Lens Anterior Eye 2018;41(2):162–68.
15. Courey C and Michaud L. Variation of clearance considering viscosity of the solution used in the reservoir and following scleral lens wear over time. Cont Lens Anterior Eye 2017;40(4):260–66.
16. Collins MJ, et al, Flexure of thin rigid contact lenses. Cont Lens Anterior Eye 2001;24(2):59–64.
17. Phillips AJ and Stone J Contact Lenses Third ed. London, UK: Butterworths; 1989.
18. Sorbara L, Fonn D and MacNeill K. Effect of rigid gas permeable lens flexure on vision. Optom Vis Sci 1992;69(12):953–8.
19. Choi J, et al. Changes of ocular higher order aberration in on- and off-eye of rigid gas permeable contact lenses. Optom Vis Sci, 2007;84(1):42–51.
20. Chen M and Yoon G. Posterior corneal aberrations and their compensation effects on anterior corneal aberrations in keratoconic eyes. Invest Ophthalmol Vis Sci 2008;49(12):5645–52.
21. Hashemi H, et al. Pentacam top indices for diagnosing subclinical and definite keratoconus. J Curr Ophthalmol 2016;28(1):21–6.
22. Barnett M and Fadel D. Scleral Lenses: The Benefits of Toric Landing Zones. C.L. Spectrum 2017;32(November):36–41.
23. Sabesan R, et al., Wavefront-guided scleral lens prosthetic device for keratoconus. Optometry and vision science : official publication of the American Academy of Optometry 2013;90(4):314–323.
24. Nave R. Coma. 2019; Available at: accessed 2019-10-25