Editors Selection (IGR: 14-3) | International Glaucoma Review #1178

Editors Selection IGR 14-3

Intraocular Pressure: 24-hour IOP measurements

Comment by Tomas Grippo on:

51115 Continuous 24-Hour Monitoring of Intraocular Pressure Patterns With a Contact Lens Sensor: Safety, Tolerability, and Reproducibility in Patients With Glaucoma, Mansouri K; Medeiros FA; Tafreshi A et al., Archives of Ophthalmology, 2012; 0: 1-6

In this prospective study, Mansouri and colleagues evaluated the short-term reproducibility of circadian IOP patterns and the individual tolerability of repeated intraocular pressure (IOP) monitoring sessions with the use of the SENSIMED Triggerfish contact lens sensor.

Forty patients with glaucoma or glaucoma suspects underwent two 24-hour IOP monitoring sessions at a one-week interval. One of the main advantages of this method to measure IOP patterns is that in contrast to traditional 24-hour IOP sleep lab studies,¹ where subjects undergo limited measurements in a controlled environment with nocturnal readings requiring awakening, it allows for almost continuous recordings while patients perform their usual daily activities including undisturbed sleep.

Short-term reproducibility of circadian IOP patterns analyzed by Pearson correlation showed fair to good agreement. Based on the incidence of adverse events and a visual analog scale score, safety and tolerability were found to be good and similar between sessions. Prior reports on one-session evaluations had also shown good tolerability.^2,3 This is the first report to assess the short-term reproducibility of IOP patterns throughout the full 24-hour cycle including undisturbed sleep. An important implication of this research is that the findings support the potential role of this technology to evaluate the effect of therapeutic interventions on 24-hour IOP. However, as the authors rightly point out, the potential influence of sources of non-IOP related artifacts are not yet fully understood requiring caution and further research. Some of these include changes in corneal shape and thickness caused by diurnal fluctuations or contact lens use, variations in corneal biomechanical properties as well as contact lens stability. This technology is also based on the assumption that changes in corneal curvature and circumference correspond to changes in IOP⁴ while output is provided in arbitrary units rather than mmHg. When evaluating for effects of therapeutic interventions, irregular daily activities and sleep times influencing IOP may confound interpretation of findings potentially requiring repeated experiments under controlled conditions.

Overall, this study is an important step forward into a better understanding of this novel technology and it's potential uses that may provide us with access to critical knowledge to further advance glaucoma care.

References

Grippo TM, Liu JH, Zebardast N, Arnold TB, Moore GH, Weinreb RN. Twenty-four-hour pattern of intraocular pressure in untreated patients with ocular hypertension. Invest Ophthalmol Vis Sci 2013; 54(1): 512-517.
Mansouri K, Shaarawy T. Continuous intraocular pressure monitoring with a wireless ocular telemetry sensor: initial clinical eperience in patients with open angle glaucoma. Br J Ophthalmol 2011; 95(5): 627-629.
De Smedt S, Mermoud A, Schnyder C. 24-hour intraocular pressure fluctuations monitoring using an ocular telemetry sensor: tolerability and functionality in healthy subjects. J Glaucoma 2012; 21(8): 539-544.
Leonardi M, Leuenberger P, Bertrand D, Bertsch A, Renaud P. First steps towards noninvasive intraocular pressure monitoring with a sensing contact lens. Invest Ophthalmol Vis Sci 2004; 45(9): 3113-3117.

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