University Hospital Pellegrin, Bordeaux, France.
Moorfields Eye Hospital, London, United Kingdom.
EyeTech
Abstract
Elevated intraocular pressure (IOP) is the main risk factor for open angle glaucoma (OAG) onset or progression. Although the role of 24-hour IOP fluctuation is still unclear, several studies have reported that the pattern of IOP fluctuations, measured with Goldman applanation tonometry (GAT) at different time of the day, was significantly different between glaucoma or ocular hypertension (OHT) and healthy eyes particularly during the nocturnal period and early in the morning. Furthermore, it has also been observed that 75% of maximal IOP peaks occur outside office hours. Inconsistency in assessing IOP fluctuation and its potential role in the pathophysiological process of OAG is mainly related to the method used to estimate IOP fluctuation with single IOP measurements using GAT at regular time intervals. Additionally, these measurements are not performed in daily life conditions for the patient. Thus a true continuous IOP monitoring is mandatory to analyze and quantify the role of IOP fluctuations in order to adjust treatment strategy earlier. A wireless contact lens sensor using a hydrophilic silicone contact lens and a strain gauge embedded within the lens have been developed (Triggerfish, Sensimed, Lausane, Switzerland) to enable a true monitoring of IOP-related fluctuations in more real daily-life conditions. 24-hour continuous changes in corneal curvature and circumference are recorded and a specific pattern is obtained for each patient. Preliminary studies have demonstrated a good reproducibility of IOP-related fluctuation patterns and few other studies have also shown specific pattern associated with OAG or OHT. We analyzed a consecutive case series of 54 eyes of 54 OAG patients with a progression assessed on visual field test with a minimum follow-up of 2 years and divided patients in 2 groups of glaucoma progression (Group 1: MD≤0.5dB/year; group 2: MD>0.5dB/year). We observed a significant difference in patterns recorded with Triggerfish between the 2 groups. Mean cosinor amplitude and mean area under the curve in nocturnal period were significantly higher in the group of faster progression. Differences in IOP-related fluctuation patterns between OAG patients with a fast progression and OAG patients with a slow progression measured with the visual field could help to improve glaucoma diagnosis and management. If these results are confirmed, 24-hour continuous IOP-related fluctuation patterns could represent a new biomarker to help predict the risk of glaucoma progression.