Elevated IOP in patients with thyroid eye disease (TED) can be caused by restriction and compression of the globe by enlarged extraocular muscles, elevated episcleral venous pressure and increased mucopolysaccharide deposition in the trabecular meshwork. Although previous studies have investigated the relationship between IOP and TED, there have been no previous studies that have evaluated the 24-hour IOP rhythms in patients with TED. The purpose of this study was to evaluate the safety and tolerability of a contact lens sensor (CLS) to measure IOP in patients with TED and to describe the 24h IOP patterns in this group of patients. The CLS is a high oxygen permeable soft contact lens with an embedded microprocessor which can measure IOP. The device is based on the approach that changes in corneal curvature and circumference are assumed to correspond to changes in IOP. An advantage of the CLS is that 24 hour IOP measurements can be taken in ambulatory conditions and undisturbed sleep. Ten patients with TED had the CLS placed on one eye for 24 hours. Study patients kept an activity diary for half hourly information of their activity, such as sleep, meals, physical activity. Results showed adverse events associated with the CLS included mild blurred vision (50%), mild hyperaemia (100%) and superficial punctate keratitis (20%). All adverse events were transient and resolved after CLS removal. Overall, when evaluating the whole study group, this model showed a nocturnal / sleep acrophase, with the peak occurring at 06:30hrs. Specifically, 50% of patients had a significant nocturnal / sleep acrophase, 20% had a significant diurnal acrophase, and 30% had no significant acrophase. The authors conclude that the CLS is a safe and well tolerated device in patients with TED and patients with TED are most likely to have a morning acrophase. 

Twenty-four hour intraocular pressure patterns in patients with thyroid eye disease.
Parekh AS, Mansouri K, Weinreb RN, et al.
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Anjali Gupta

Birmingham and Midland Eye Centre, Birmingham, UK.

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