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Florentina J. Freiberg, Jeanette Lindell, Luisa A. Thederan, Swetlana Leippi, Yanan Shen, Franz Grehn, Thomas Klink; Central Corneal Thickness After Overnight Wear Of An Intraocular Pressure Fluctuation Contact Lens Sensor. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5076.
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SENSIMED Triggerfish® is a medical device intended for continuous recording of intraocular pressure (IOP) fluctuation. It relies on a contact lens (CL) with an embedded strain gauge that reacts to circumferential changes at the corneo-scleral junction. This contact lens sensor (CLS) may induce adverse effects also known with classic vision correction CL, such as corneal swelling. Corneal thickness changes may potentially affect the CL-based IOP monitoring. Therefore we investigated the effect on central corneal thickness (CCT) of overnight CLS wear and the influence of swelling on the profile recorded with the CLS.
A prospective, randomised, single-centre study was performed on 20 patients diagnosed with ocular hypertension or glaucoma, investigating the effect of overnight CLS wear on CCT. Additionally, changes in central corneal radius (CCR) were recorded. The information from the CLS is transferred via wireless power using a peri-orbital antenna and a cable connected to a portable recorder that stores the data. Data is then downloaded to a computer, displaying a graph in arbitrary units, proportional to the electric signal generated by the strain gauge. CCT was measured by ultrasound pachymetry. Corneal thickness and curvature were obtained from topographical data. Differences in CCT, CCR and IOP were calculated as change from pre- to post-sleep.
In the primary analysis set (n=15) CCT changed significantly pre- to post-study in the study eye (523 to 537 µm, difference 14 µm±20; p=0.015) and not significantly in the fellow eye (518 to 522 µm, difference 4 µm±13; p=0.206). The change from baseline CCT between the study and the fellow eye however was not statistically significantly different (p=0.075). Corneal topography showed some thickening of the central portion of the cornea in the study eye (24 µm; p=0.026) and in the fellow eye (4 µm; p=0.437). There was no statistically significant difference in mean Snellen BCVA between the eyes.
The CLS has some effect on central and mid-peripheral corneal thickness during overnight wear, without significant difference to the contralateral, non lens-wearing eye. The continuous IOP monitoring with the CLS does not appear to be affected by differences in CCT that occur during CLS wear. No significant change in BCVA was recorded.
Ethik Kommission Würzburg, 107/10
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