Evaluation of surface water characteristics of novel daily disposable contact lens materials, using refractive index shifts after wear

Figures & data

Table 1 Contact lenses evaluated

Material	Water content	FDA group	Brand name	Manufacturer
Delefilcon A	≥80% (surface) 33% (bulk)	V	Dailies Total1^®	Alcon (Fort Worth, TX, USA)
Nesofilcon A	78%	II	Biotrue^® ONEday	Bausch & Lomb Incorporated (Rochester, NY, USA)
Etafilcon A	58%	IV	ACUVUE^® MOIST	Vistakon (Jacksonville, FL, USA)

Abbreviation: FDA, US Food and Drug Administration.

Table 2 Refractive indices of reference materials⁴⁰

Material	Index of refraction (λ=589.3 nm)
Air	1
Water	1.33
HEMA	1.43
20% water hydrogel	1.46–1.48
75% water hydrogel	1.37–1.38
Human cornea	1.376

Notes: This table was originally published in the Dictionary of Optometry and Visual Science, 7th ed. Millodot M, Page No 167, Copyright © 2009 Butterworth-Heinemann Elsevier.⁴⁰ Copyright ©2013 Bausch and Lomb. Reproduced with permission, from Schafer J, Steffen RB. Evaluation of surface water characteristics of novel daily disposable contact lenses using refractive index shifts after wear. Poster presented at Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO); 5 May 2013; Seattle, WA, USA.⁵²

Abbreviation: HEMA, hydroxyethyl methacrylate.

Table 3 Surface refractive indices of contact lenses before and after 15 minutes of wear

Lens	Group	N	Minimum	Maximum	Mean	Standard deviation	Difference (worn–unworn)	P-value (t-test)
Nesofilcon A^Citation24	Unworn	10	1.374	1.376	1.375	0.0008	0.0064	<0.0001
	Worn	20	1.377	1.385	1.381	0.0021
					1.375a
Etafilcon A^Citation51	Unworn	10	1.403	1.407	1.405	0.0013	0.0123	<0.0001
	Worn	20	1.413	1.431	1.417	0.0046
					1.40a
Delefilcon A^Citation25	Unworn	10	1.336	1.338	1.337	0.0005	0.0932	<0.0001
	Worn	20	1.425	1.440	1.430	0.0031
					1.42a

Notes: The refractive index value for nesofilcon A reported in the table was determined by the test method used in this study, whereas those of etafilcon A and delefilcon A are as reported by their respective manufacturers in regulatory submissions using different test methods.

a As reported in the respective FDA documents cited in the Lens column.

Figure 1 Water loss over the course of 1 wearing-day.

Notes: Circle, nesofilcon A; square, etafilcon A. Mean + standard deviation. Lower error bar omitted for clarity (Steffen and Schafer, unpublished data 2013).

MillodotMDictionary of Optometry and Visual Science7th edOxford, UKButterworth-Heinemann2009

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FDA 510(k) Summary K113703. Bausch + Lomb nesofilcon A contact lens. June 5, 2012

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FDA 510(k) Summary K062614. Special 510(k) Summary of Safety and Effectiveness. (VISTAKON® (etafilcon A) Soft (hydrophilic) Contact Lens, Clear and Tinted (Visibility and/or Cosmetically) with UV Blocker for Daily Wear). November 1, 2006

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