Effect of overnight wear of the Triggerfish(®) sensor on corneal thickness measured by Visante(®) anterior segment optical coherence tomography

Purpose: To evaluate the effect of overnight wear of the Triggerfish(®) contact lens sensor (CLS) on central corneal thickness (CCT) using the Visante(®) anterior segment optical coherence tomography (AS-OCT).

Methods: Twelve healthy subjects were studied in a sleep laboratory. An ophthalmic examination including ultrasonic CCT, corneal topography, specular microscopy and AS-OCT CCT was performed. Starting at 7 pm, the Triggerfish(®) CLS was fitted on one randomly selected eye. Similar AS-OCT measurements were taken on both eyes every 2 hr from 8 pm to 8 am. The CLS was removed just after the 8 am measurement session. Measurements were repeated at 9 am.

Results: Twenty-four eyes of 12 subjects were studied (mean age, 22.1 ± 2.4 years; four men/eight women). CCT significantly increased during the night in both CLS and control eyes (p < 0.01). The maximal change was +4.4 ± 1.7% in the CLS eyes and +2.9 ± 1.8% in the control eyes (p < 0.05). Throughout the night, CCT significantly increased more in eyes with CLS than in control eyes (p < 0.05). There were significantly more corneal curvature irregularities after overnight wear of the CLS than in the control eye: +1.63 Dioptre (D) versus -0.02 D in the 3-mm central zone and +3.17 D versus +0.01 D in the 5-mm central zone (p < 0.01).

Conclusion: CCT and corneal curvature irregularities increased slightly but significantly more in eyes with the Triggerfish(®) CLS than in control eyes during overnight wear. Further studies are required to determine whether the corneal curvature changes modify the signal recorded by the sensor.