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O'Rese J Knight, Jean-Claude Mwanza, T. Brooks Owens, Scott David Lawrence, Anthony J Viera, Donald L Budenz; SENSIMED Triggerfish® Contact Lens Sensor Interactions with the Cornea. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5741. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the effects of corneal curvature and thickness on Triggerfish (Sensimed AG, Lausanne, Switzerland) contact lens sensor (CLS) measurements and determine the effect of 24 hour lens wear on corneal curvature and thickness.
Thirteen patients with normal tension glaucoma (NTG) and 11 healthy subjects underwent 24 hour intraocular pressure (IOP) recording with the CLS and corneal topographic measurements with the Galilei G4 (Ziemer Ophthalmic Systems AG, Switzerland) before and after wearing the CLS. Pre- and post- CLS keratometry and central (CCT), mid (MCT) and peripheral (PCT) corneal thickness were measured. Pre- and post-contact lens corneal topographic data were compared using paired t-test. Multivariate regression was used to assess the effect of cornal topographic measurement on the CLS output.
Mean age of participants was 61 ± 15 years; 46% of participants were female and 58% had NTG. The mean pre-CLS FlatK, SteepK, and Astigmatism (D) was 42.84 ± 1.5, 43.65 ± 1.7, and 0.87 ± 0.6; the CCT, MCT and PCT (µm) was 561.7 ± 34.7, 604.9 ± 35.3, and 662.4 ± 41.3, respectively. The mean 24 hr CLS was 74.64 ± 88.98 mV. There was a significant inverse relationship between CCT and 24hr CLS measurements (β = -0.598; p = 0.002). None of the other corneal parameters affected the CLS measurements. The pre- versus post-CLS mean difference in FlatK, SteepK, and astigmatism was 0.21D (p = 0.194), 0.48D (p = 0.695), and -0.382D (p = 0.034). The pre- versus post-CLS mean difference in CCT, MCT, and PCT was 1.3 µm (p = 0.545), -1.8 µm (p = 0.381), and -15.0 µm (p < 0.005), respectively.
Increased corneal thickness may decrease CLS measurements. Increased peripheral corneal thickness induces a relative flattening of the cornea over the 24 hour period.
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