Using sensors to estimate intraocular pressure: a review of intraocular pressure telemetry in clinical practice

Measurement of intraocular temperature in glaucoma: week-day and seasonal fluctuations

PURPOSE

To evaluate long-term intraocular temperature (IOT) variations in eyes with primary open-angle glaucoma (POAG) using an intraocular telemetric sensor.

METHODS

This prospective, open-label, multicentre observational study analysed the IOT variations in 22 eyes of 22 patients with POAG. All enrolled patients underwent implantation of an intraocular pressure (IOP) sensor during cataract surgery. The telemetric system uses a built-in temperature sensor to control measured IOP for temperature. Each time a patient measures their IOP, both the IOP and IOT are recorded in the reader device. Patients were instructed to self-measure their IOP as often as desired, but at least four times daily. Recorded readings were retrieved and analysed using mixed effect models and pairwise comparisons using Bonferroni correction to assess the statistical significance of average IOT variations between each individual weekday and calendar month.

RESULTS

The mean age of patients was 67.8±6.8 years and 36.4% were women. A total of 132 745 readings over 21 102 measurement-days were obtained. On average, IOT was significantly higher on Sundays (34.57°C; 95% CI 34.37 to 34.78) than on any other day of the week (p<0.001). Mean IOT on other weekdays ranged from 34.48°C to 34.51°C. Over the year, IOT followed a clear seasonal pattern, reaching its maximum in July (34.8°C; 95% CI 34.56 to 34.97) and its minimum in January (34.4°C; 95% CI 34.15 to 34.56; p<0.001).

CONCLUSIONS

This study demonstrates the feasibility of continual and long-term measurement of IOT using intraocular sensors. The results show significant short-term and long-term fluctuations of IOT. Research is warranted to understand the impact of IOT variations on IOP, ocular perfusion and glaucoma progression.

Real-Time Monitoring of Intraocular Pressure in Glaucoma Patients Using Wearable Mobile Medicine Devices

Glaucoma is caused by excessive aqueous humor in the eye, resulting in a continuous or intermittent increase of intraocular pressure, which exceeds the tolerance of the eyeball and damages the optic nerve. Existing treatments for glaucoma do not work well or have significant side effects. Intraocular pressure signal is a very important physiological signal that needs real-time and accurate monitoring in glaucoma patients, especially in severe glaucoma patients. Therefore, long-term, real-time, and accurate monitoring of intraocular pressure is of great significance for the diagnosis and treatment of glaucoma patients. The use of wearable devices for real-time ocular diagnosis and treatment of glaucoma patients is an effective approach. However, the current commonly used intraocular pressure measurement and monitoring technology is difficult to meet the diagnosis and monitoring needs of glaucoma patients in terms of size, measurement accuracy, power consumption, and intelligence. Therefore, facing the needs of glaucoma disease treatment, this topic studies an implantable flexible intraocular pressure sensor for long-term continuous monitoring of intraocular pressure in glaucoma patients and mainly focuses on the working principle, structural design, process fabrication, measurement and control system, characterization, and performance test of the intraocular pressure sensor. It is of great significance for personalized and accurate treatment of glaucoma patients.

Triggerfish Recording of IOP Patterns in Combined HFDS Minimally Invasive Glaucoma and Cataract Surgery: A Prospective Study

BACKGROUND

The aim of the study is to investigate whether the circadian IOP rhythm can be influenced by combined cataract surgery with high frequency deep sclerotomy (HFDS) and whether intraocular pressure (IOP) can be significantly reduced by HFDS.

METHODS

In our study 10 patients were included, in whom 24 h IOP monitoring was installed before and after HFDS/cataract surgery using a Triggerfish. HFDS is a minimally invasive glaucoma surgery (MIGS).

RESULTS

After performed HFDS combined with cataract surgery, the IOP was reduced from 27.7 ± 2.11 mmHg to 14.4 ± 2.59 mmHg, which is highly significant (p < 0.001). The contact lens sensor (CLS) cosinor analysis pre- and postoperatively showed that the circadian rhythm is not influenced by the surgery, i.e., the circadian IOP rhythm did not show significant differences before and after surgery.

CONCLUSIONS

HFDS combined with cataract surgery is a potent surgical method that can significantly reduce the IOP. However, the circadian rhythm cannot be changed by the surgery. The acrophase remained during the night in all patients.

Intraocular Pressure Variations After Intravitreal Injections Measured With an Implanted Suprachoroidal Telemetry Sensor

PURPOSE

Intravitreal injections (IVIs) may create transient intraocular pressure (IOP) elevation. This report describes continuous IOP fluctuations following multiple IVI measured with a permanent implantable sensor.

PATIENTS AND METHODS

We report the case of a 49-year-old white glaucomatous male with refractory macular edema secondary to central retinal vein occlusion in his left eye who underwent deep sclerectomy combined with the implantation of a suprachoroidal tonometry sensor. Serial IOP measurements were performed immediately before and after each IVI over a 1-year period.

RESULTS

During the first 7 months following deep sclerectomy, IOP remained below 10 mm Hg. During this period, mean IOP before each injection was 2.1±2.6 mm Hg, and each IVI caused a reduction of 1.2±0.8 mm Hg on average, with a maximum reduction of 2.7 mm Hg, before IOP normalized within 50 minutes to 24 hours. From 7 months postoperatively, mean IOP increased to the low teens. During this period, mean IOP before each injection was 9.9±1.8 mm Hg, and each IVI caused an increase of 15.8±11.7 mm Hg on average, with a maximum increase of 44.8 mm Hg, before IOP normalized within 20 minutes to 4 hours.

CONCLUSIONS

During the initial postoperative phase, IVI may cause acute reduction in IOP, either through subconjunctival leaks or increased filtration secondary to increased fluid pressure. Several months after surgery, this effect subsides and IOP spikes sharply immediately after each IVI, suggesting the resolution of the initial mechanism, most likely through scarring and fibrosis.

CLEAR - Contact lens technologies of the future

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses. This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases. The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

COVID-19 Launches Retinal Telemedicine into the Next Frontier

INTRODUCTION

Telemedicine in ophthalmology, and specifically in retinal diseases, has made significant advancements in recent years. The COVID-19 pandemic has launched telehealth into a new era by creating demand from patients and physicians alike, while breaking down previous insurance, reimbursement, access and educational barriers.

METHODS

This paper reviews mulitple studies demonstrating the use of telemedicine in managing various retinal conditions before and during the COVID-19 pandemic.

CONCLUSION

Moving forward, promising new devices and models of care ensure that tele-retinal care will continue to expand and become a vital part of how we screen, diagnose and monitor retinal diseases.

Intereye Symmetry of 24-Hour Intraocular Pressure-related Patterns in Untreated Glaucoma Patients Using a Contact Lens Sensor

PURPOSE

Scarce data are available on the symmetry of 24-hour intraocular pressure (IOP) variations between fellow eyes of glaucoma patients, and such evidence could have profound consequences on the interpretation of monocular therapeutic trials. The objective is to evaluate the intereye correlation of continuously measured circadian IOP-related patterns in untreated glaucoma patients.

METHODS

In this single-center prospective study, a total of 29 untreated patients with open-angle glaucoma underwent bilateral ambulatory 24-hour monitoring of IOP-related patterns using a contact lens sensor (CLS; SENSIMED Triggerfish). IOP was measured before and after CLS monitoring using Goldmann applanation tonometry. Intereye agreement of 24-hour patterns was calculated using Spearman correlation (r) of raw data and after cosinor rhythmometry modeling.

RESULTS

Complete bilateral CLS data could be obtained in 20 patients (mean age: 55.5±15.7 y; 51.7% women). On average, intereye correlation was r=0.76±0.19 (range: 0.16 to 0.95) and r=0.77±0.15 (range: 0.49 to 0.91), after excluding 8 patients with lower quality recordings. Cosine rhythmometry modeling showed mean acrophases occurring at 4:21±2:20 AM in left eyes and 3:39±1:50 AM in right eyes (r=0.48; P=0.034). Mean acrophase amplitude was 110.9±51.9 for left eyes and 107.8±46.2 for right eyes (r=0.79; P<0.001). No serious adverse events related to CLS monitoring were recorded. Transient conjunctival hyperemia (13 patients) and blurred vision (11 patients) were the most frequent adverse events.

CONCLUSIONS

In this group of untreated glaucoma patients, there was good intereye agreement for circadian IOP-related patterns using the CLS. These results show a higher degree of intereye symmetry, in terms of IOP peak timings and amplitudes, than previously reported with standard tonometry.