Contact lens sensors are special devices designed to measure your eye pressure (intraocular pressure or IOP) continuously over 24 hours. Unlike the standard eye pressure checks you receive during office visits, these devices can track pressure changes throughout the day and night, including while you sleep.
The Triggerfish Contact Lens Sensor
The Triggerfish (also called SENSIMED Triggerfish) is currently the most well-studied contact lens sensor and has been approved for use in the United States and other countries.[1][2] It has been around for a couple decades. This device looks like a soft contact lens but contains tiny sensors embedded within it.
How It Works:
You wear the contact lens for 24 hours while going about your normal activities
The lens detects changes in the shape of your eye that occur when pressure changes
A small wireless antenna worn around your eye sends data to a portable recorder you carry with you
Your doctor reviews the data after the 24-hour period
Important Limitations:
The Triggerfish does not measure your actual eye pressure in the standard units (mmHg) that your doctor normally uses. Instead, it measures relative changes in eye pressure and reports them in different units (millivolt equivalents).[2] This means your doctor can see patterns of when your pressure goes up or down, but cannot see the exact pressure numbers.
What Research Shows
Studies have found that the Triggerfish contact lens sensor is generally safe and well-tolerated by patients for limited use. It cannot be worn every day.[2] The Triggerfish is very expensive and not suitable to replace regular contact lenses. It cannot even replace the iCare home tonometer for patient use. Research suggests it may be helpful for:
Detecting nighttime pressure patterns that cannot be measured during regular office visits[3][4]
Identifying patients at higher risk for glaucoma getting worse[5][6]
Revealing pressure fluctuations that occur during sleep or with different body positions[3]
In one study of 54 glaucoma patients, those with faster disease progression showed greater 24-hour pressure fluctuations on the contact lens sensor compared to those with slower progression.[5] Another study found that certain patterns detected by the sensor were associated with prior rates of visual field loss.[4]
Newer Technologies in Development
Scientists are actively developing improved contact lens sensors that can measure actual eye pressure in standard units (mmHg) rather than just relative changes.[7][8] Some experimental devices have shown the ability to:
Provide continuous pressure readings in mmHg throughout 24 hours[7][8]
Work with standard soft contact lenses that people already wear[9]
Potentially deliver glaucoma medication automatically when pressure gets too high[10]
These newer technologies are still being tested and are not yet available for routine clinical use.[11]
Should You Consider Contact Lens Monitoring?
Your eye doctor may recommend 24-hour contact lens monitoring if:
Your glaucoma is getting worse despite treatment
Your office pressure readings seem normal, but your doctor suspects nighttime pressure spikes
You have normal-tension glaucoma (damage occurring at seemingly normal pressures)
Your doctor needs more information to adjust your treatment plan
What to Expect
If your doctor recommends contact lens sensor monitoring:
You will typically need to stay overnight at a medical facility or be closely monitored
The lens is worn for 24 hours, then removed
Most patients tolerate the device well, though some report discomfort[2]
Your doctor will review the pressure patterns and discuss what they mean for your treatment
Current Status
The Triggerfish contact lens sensor is commercially available and has been used in clinical practice and research studies worldwide.[1][2] However, it is NOT routinely used for all glaucoma patients. It is not a very practical device for most patients.
Questions to Ask Your Doctor
Would 24-hour pressure monitoring help manage my glaucoma?
What specific information are you hoping to learn from this test?
How will the results change my treatment plan?
Are there other ways to assess my eye pressure patterns?
The Bottom Line
Contact lens sensors represent an evolving technology for monitoring eye pressure in glaucoma. While the Triggerfish device is currently available and has shown promise in research studies, it provides pattern information rather than exact pressure readings and it has many other limitations. Newer devices are being developed that may offer improved accuracy and ease of use. Talk with your eye doctor about whether this type of monitoring might benefit your glaucoma care.
References
- Primary Open-Angle Glaucoma Preferred Practice Pattern®. Gedde SJ, Vinod K, Wright MM, et al. Ophthalmology. 2021;128(1):P71-P150. doi:10.1016/j.ophtha.2020.10.022.
- The Sensimed Triggerfish Contact Lens Sensor: Efficacy, Safety, and Patient Perspectives. Dunbar GE, Shen BY, Aref AA. Clinical Ophthalmology (Auckland, N.Z.). 2017;11:875-882. doi:10.2147/OPTH.S109708.
- Twenty-Four-Hour Intraocular Pressure-Related Patterns From Contact Lens Sensors in Normal-Tension Glaucoma and Healthy Eyes: The Exploring Nyctohemeral Intraocular Pressure Related Pattern for Glaucoma Management (ENIGMA) Study. Kim YW, Kim JS, Lee SY, et al. Ophthalmology. 2020;127(11):1487-1497. doi:10.1016/j.ophtha.2020.05.010.
- Association Between 24-Hour Intraocular Pressure Monitored With Contact Lens Sensor and Visual Field Progression in Older Adults With Glaucoma. De Moraes CG, Mansouri K, Liebmann JM, Ritch R. JAMA Ophthalmology. 2018;136(7):779-785. doi:10.1001/jamaophthalmol.2018.1746.
- 24-Hour Monitoring of Intraocular Pressure Fluctuations Using a Contact Lens Sensor: Diagnostic Performance for Glaucoma Progression. Gaboriau T, Dubois R, Foucque B, Malet F, Schweitzer C. Investigative Ophthalmology & Visual Science. 2023;64(3):3. doi:10.1167/iovs.64.3.3.
- Prediction of Glaucoma Progression by 24-H Contact Lens Sensor Profile in Patients With Normal-Tension Glaucoma. Higashide T, Udagawa S, Nakazawa K, et al. Scientific Reports. 2024;14(1):21564. doi:10.1038/s41598-024-72556-z.
- Continuous 24-Hour Measurement of Intraocular Pressure in Millimeters of Mercury (mmHg) Using a Novel Contact Lens Sensor: Comparison With Pneumatonometry. Gillmann K, Wasilewicz R, Hoskens K, Simon-Zoula S, Mansouri K. PloS One. 2021;16(3):e0248211. doi:10.1371/journal.pone.0248211.
- First-in-Human Continuous 24-Hour Measurement of Intraocular Pressure and Ocular Pulsation Using a Novel Contact Lens Sensor. Wasilewicz R, Varidel T, Simon-Zoula S, et al. The British Journal of Ophthalmology. 2020;104(11):1519-1523. doi:10.1136/bjophthalmol-2019-315276.
- Smart Soft Contact Lenses for Continuous 24-Hour Monitoring of Intraocular Pressure in Glaucoma Care. Zhang J, Kim K, Kim HJ, et al. Nature Communications. 2022;13(1):5518. doi:10.1038/s41467-022-33254-4.
- Wireless Theranostic Smart Contact Lens for Monitoring and Control of Intraocular Pressure in Glaucoma. Kim TY, Mok JW, Hong SH, et al. Nature Communications. 2022;13(1):6801. doi:10.1038/s41467-022-34597-8.
- Current and Emerging Technologies for Continuous Intraocular Pressure Monitoring in the Control of Glaucoma Progression: A Scoping Review. Monsálvez-Romín D, Martínez-Albert N, García-Domene MC, Ortí-Navarro S. Journal of Clinical Medicine. 2025;14(24):8795. doi:10.3390/jcm14248795.