Self-tonometry as a complement in the investigation of glaucoma patients

Repeated Measurements Are Necessary for Evaluating Accurate Diurnal Rhythm Using a Self-Intraocular Pressure Measurement Device

PURPOSE

To investigate how many tests need to be performed to adequately assess intraocular pressure (IOP) diurnal change using a self-measuring rebound tonometer among glaucoma patients.

SUBJECTS AND METHODS

Adult patients with primary open-angle glaucoma were included. IOP was measured in the morning (6 AM to 9 AM), afternoon (12 PM to 3 PM), and at night (6 PM to 9 PM) for seven consecutive days. Twenty-four (7 males and 17 females, mean age 59.5 ± 11.0 years) patients who successfully measured IOP at least three times per day during the correct time periods for four days were subjected to analysis.

RESULTS

The IOP rhythm was significantly greater on the first day of measurement (6.6 ± 3.6 mmHg) than that averaged during subsequent days (4.4 ± 2.2 mmHg). The time of the highest and lowest IOP measurements on the first day of IOP measurement and during the entire measurement period coincided in 72.9% and 64.6% of cases, respectively. The concordance rate of the highest IOP time between the whole measurement period and each measurement day was less than 60%.

CONCLUSION

The diurnal IOP rhythm measured by the patients themselves was not consistent, and multiple days of measurements may be necessary to correctly assess diurnal IOP rhythm.

Impact of self-tonometry on glaucoma treatment decision

PURPOSE

The aim of this study was to examine the impact of self-tonometry on clinicians' decision in glaucoma treatment.

MATERIALS AND METHODS

Medical records of 133 patients who had performed self-tonometry using iCare^® Home between January and December 2019 were retrospectively reviewed. Inclusion criteria were as follows: age over 18 years, all types of glaucoma, as well as ocular hypertension and glaucoma suspect, compliance with tonometer manufacturer's recommendations and monitoring over at least 2 days. The data consisted of age, gender, diagnosis, visual field index, rate of progression and type of treatment pre- and post-intraocular pressure (IOP) phasing. The following IOP measurements were used to calculate the mean and maximum IOP, and range over each day and consecutive days: Goldmann applanation tonometry (GAT) measurements from referral and training visits and iCare^® Home measurements made by the trainers and the patients themselves. A total of 90 patients were included.

RESULTS

Clinicians were satisfied with the actual treatment in 54.4% of the cases. There was a statistically significant difference between the clinicians' decision to maintain same treatment or to escalate therapy for all the mean and maximum IOPs measured on each single day and over a 2- or 3-day period (p < 0.002).

CONCLUSION

Our results suggest that the presence of high IOP values obtained with self-tonometry supports an intensification of glaucoma treatment. Self-tonometry provides clinicians with an important complement for clinical decision-making, and under- or over-treatment may be avoided for the benefit of patients.

iCare® Home vs Goldmann applanation tonometry: Agreement of methods and comparison of inter-observer variation at a tertiary eye centre

Purpose: To investigate whether the inter-observer variation is similar between the Goldmann applanation tonometer used by healthcare staff and the iCare® Home tonometer used by glaucoma patients, volunteers and healthcare staff. Methods: Sixty-one participants were recruited to the study, including 24 glaucoma patients. Seven participants were excluded. For each participant, intraocular pressure (IOP) was measured on the same occasion by two different healthcare staff using GAT as well as by a healthcare staff and the participant using the iCare® Home tonometer. Results: Seventy-two per cent of iCare® measurements were within 3 mmHg of the GAT measurements. There was a statistically significant difference between the trainers' measurements made with iCare® Home and those made with GAT (p < 0.001), as well as between the GAT measurements made by trainers and those made by extra personnel (p = 0.017). The strongest correlation was between iCare® Home participants' and trainers' measurements (0.934). The correlation between different users with GAT was lower (0.769). The inter-user agreement was excellent for iCare® Home users (95% CI 0.93, ranging from 0.880 to 0.959) and moderate for GAT users (95% CI 0.741, ranging from 0.558 to 0.849). Conclusion: Our study found that tonometry with iCare® Home has similar or less inter-user variation compared with GAT.

Adherence to Therapy in Glaucoma Treatment—A Review

Glaucoma is a chronic disease and the second leading cause of irreversible vision loss worldwide, whose initial treatment consists of self-administered topical ocular hypotensive eyedrops. Adherence with glaucoma medications is a fundamental problem in the care of glaucoma patients as up to 50% of patients fail to receive the intended benefits of the treatment. The literature has identified many barriers to patients’ compliance, from factors depending on the type of medication administered, communication between physician and patients, to factors dependent on patients’ behaviour and lifestyle. Failure to take medication as prescribed increases the risk that patients will not receive the desired benefit, which often leads to a worsening of the disease. Our aim is to synthesize the methods used for measuring adherence of patients to glaucoma therapy and the interventions used for addressing adherence, laying emphasis on a patient-centred approach, taking time to educate patients about their chronic disease and to assess their views on treatment.

Accuracy and Reliability of Self-measured Intraocular Pressure in Glaucoma Patients Using the iCare HOME Tonometer

PRCIS

The iCare HOME tonometer is a useful tool which can be used by patients for fairly accurate and reliable self-measurement of intraocular pressure (IOP).

PURPOSE

The aim was to compare the accuracy of IOP measurements of trained glaucoma patients using the iCare HOME tonometer before and after a week of self-monitoring at home and study the repeatability of patient measurements done at home.

MATERIALS AND METHODS

A total of 40 glaucoma patients had IOPs measured using the Goldmann applanation tonometer and the iCare HOME. Patients were trained to use the iCare HOME and measured their IOP twice daily over a loan period of 7 days. Bland-Altman analysis was used to assess agreement between Goldmann applanation tonometer and iCare HOME readings. Intraclass correlation coefficient compared inter-rater reliability of iCare HOME measurements, and test-retest variability for the patient's readings over the 7-day period were analyzed. A 5-point Likert scale questionnaire was used to assess the patient's experience with the device.

RESULTS

Up to 32 patients (80%) were able to obtain IOP readings within 3 mm Hg of the glaucoma nurse clinician's readings at the preloan visit, and up to 36 patients (90%) at the postloan visit. Good inter-rater reliability was observed between iCare HOME measurements by the glaucoma nurse clinician and patients. At the postloan visit, inter-rater reliability was good for right eye readings and excellent for left eye readings. No distinct trend in test-retest variability was identified over the 7-day period. 65% of patients agreed the device was easy to use and 89% would recommend the device to other glaucoma patients.

CONCLUSION

Patients trained to use the iCare HOME device can do so with fair accuracy compared with trainers with accuracy improving within 1 week of usage.

Clinical Trial: Diurnal IOP Fluctuations in Glaucoma Using Latanoprost and Timolol with Self-Tonometry

SIGNIFICANCE

Assessment of treatment efficacy via comparison with a target IOP is fundamental in monitoring patients with open-angle glaucoma and ocular hypertension. This article highlights that diurnal IOP fluctuations obtained using self-tonometry may more accurately reflect IOP responses to therapy.

PURPOSE

This study aimed to investigate fluctuations in diurnal IOP measurements in patients with open-angle glaucoma and ocular hypertension treated with latanoprost 0.005% and timolol 0.25%.

METHODS

In this crossover treatment trial, 14 participants performed self-tonometry with iCare HOME 4 times daily for (1) 1 week using latanoprost, (2) 4 weeks using no medications, and (3) 2 weeks using timolol. Daily peak IOPs, IOP fluctuations, and mean IOPs from different treatments were compared on an individual basis. Treatment efficacy between medications was assessed by comparing mean percentage IOP reductions with latanoprost and timolol across participants. In addition, effects of age, years since commencing latanoprost, sex, and diagnosis were investigated, and peak IOP times were compared with assess impacts on diurnal profiles.

RESULTS

Between individuals, IOP responses ranged from reductions in peak IOPs, IOP fluctuations, and mean IOPs on both medications to no change in any parameter and medication. IOP fluctuations showed greater mean percentage reductions than did peak and mean IOPs (χ2 = 16.51, P = .002). There were significant associations between years since commencing latanoprost and peak and mean IOP responses on timolol (r = 0.69, P = .007), and sex and relative reductions in IOP fluctuations on both medications (P = .03). There were no differences in peak IOP times between treatment conditions.

CONCLUSIONS

Despite variability in IOP responses to latanoprost and timolol, IOP fluctuation with self-tonometry was more consistent in evaluating target IOP, reflecting its importance in ascertaining true IOP response to topical therapies. These findings may impact clinical decision making based on target IOP criteria in patients on topical therapy.

The Future Is Now: Incorporating Telemedicine into Glaucoma Care

Purpose of Review

The field of teleglaucoma has expanded rapidly in recent years with several large-scale teleglaucoma screening programs in existence throughout the world. Additionally, teleglaucoma programs for use in disease management are under study. The limited access to care that resulted from the COVID-19 pandemic highlighted the need for expansion of such programs. This article reviews the literature on teleglaucoma for screening and management of glaucoma, discussing considerations for incorporating teleglaucoma into clinical practice.

Recent Findings

Teleglaucoma screening reduces the rate of false-positive referrals and can accurately screen at-risk populations with accuracy similar to in-person screening. The use of teleglaucoma for the management of glaucoma shows promise for low-risk patients with early disease. Furthermore, teleglaucoma is cost-effective and reduces travel burden for patients resulting in high patient satisfaction.

Summary

Teleglaucoma offers potential for improving access to glaucoma care, reducing the burden on patients and health care systems.

Virtual Ophthalmology: Telemedicine in a COVID-19 Era

Purpose

To discuss the effects of the severe acute respiratory syndrome coronavirus 2 betacoronavirus on ambulatory ophthalmology practices, the value proposition of telemedicine, teleophthalmology implementation methodologies, and the accelerated future of telemedicine.

Design

Review of the current telehealth landscape including usage, policies, and techniques for ambulatory practice integration.

Methods

We provide author-initiated review of recent trends in telehealth, governmental recommendations for health care delivery during the COVID-19 pandemic, and a PubMed Central query for telemedicine in ophthalmology or teleophthalmology. In addition, the authors' comprehensive experience in telemedicine design and implementation is provided.

Results

We provide a summary describing the present state of telehealth, teleophthalmology modeling, care delivery, and the proposed impact of telehealth surges on the future of ophthalmology practice.

Conclusion

Recent patient and provider interest in telemedicine, the relaxation of regulatory restrictions, increased remote care reimbursement, and ongoing social distancing practices compel many ophthalmologists to consider virtualizing services.

Initial experience in self-monitoring of intraocular pressure

Background/aims

Diurnal variation in intraocular pressure (IOP) is a routine assessment in glaucoma management. Providing patients the opportunity to perform self-tonometry might empower them and free hospital resource. We previously demonstrated that 74% of patients can use the Icare® HOME tonometer. This study further explores Icare® HOME patient self-monitoring.

Methods

Patients were trained by standard protocol to use the Icare® HOME rebound tonometer. Patient self-tonometry was compared to Goldmann applanation tonometry (GAT) over one clinical day. Following this, each patient was instructed to undertake further data collection that evening and over the subsequent two days.

Results

Eighteen patients (35 eyes) participated. Good agreement was demonstrated between GAT and Icare® HOME for IOPs up to 15 mm Hg. Above this IOP the Icare® tended to over-read, largely explained by 2 patients with corneal thickness >600 um. The mean peak IOP during ‘clinic hours’ phasing was 16.7 mm Hg and 18.5 mm Hg (p = 0.24) over three days. An average range of 5.0, 7.0 and 9.8 mm Hg was shown during single day clinic, single day home and three day home phasing respectively (p =<0.001). The range of IOP was lower in eyes with prior trabeculectomy (6.1 mm Hg vs 12.2 mm Hg). All patients undertook one reading in the early morning at home with an average of 4.8 readings during, and 3.1 readings after office hours.

Conclusions

This small study shows that self-tonometry is feasible. The findings from home phasing demonstrated higher peak and trough IOPs, providing additional clinical information. Home phasing is a viable alternative. The cost-effectiveness of this approach has yet to be addressed.

Determining Significant Elevation of Intraocular Pressure Using Self-tonometry

SIGNIFICANCE

Icare HOME rebound tonometry is increasingly adopted into clinical practice for IOP phasing of glaucoma patients and suspects. Because of measurement differences with applanation tonometry and diurnal fluctuations, interpretation of the IOP measured with Icare HOME phasing can be challenging.

PURPOSE

The purpose of this study was to use a large patient cohort to develop a practical, analytical tool for interpreting Icare HOME measurements with respect to applanation pressure.

METHODS

IOP measurements using the Icare HOME and an applanation tonometer were taken prospectively in 498 consecutive patients. Bland-Altman, frequency distribution, and linear regression analysis were applied to determine measurement differences. A novel criterion, Threshold Icare HOME IOP, was developed to assist identification of elevation above target applanation pressure, considering the expected diurnal variation and measurement variability.

RESULTS

Icare HOME tended to underestimate applanation tonometry (mean bias, -1.7 mmHg; 95% limits of agreement, -7.0 to +3.6). Overall, differences were within ±3 mmHg in 71.5% and ±5 mmHg in 92% of patients. Based on the novel criterion developed, Icare HOME measurements that exceed target applanation pressure by 6 mmHg or greater are generally outside the 95% limit of expected observations.

CONCLUSIONS

The Threshold Icare HOME IOP is a novel and practical criterion that can assist clinicians in their interpretation of Icare HOME phasing measurements with respect to target applanation pressures. Elevation above the expected thresholds may prompt closer monitoring or even modifications to glaucoma management.

Practice Guidelines for Ocular Telehealth-Diabetic Retinopathy, Third Edition

Contributors The following document and appendices represent the third edition of the Practice Guidelines for Ocular Telehealth-Diabetic Retinopathy. These guidelines were developed by the Diabetic Retinopathy Telehealth Practice Guidelines Working Group. This working group consisted of a large number of subject matter experts in clinical applications for telehealth in ophthalmology. The editorial committee consisted of Mark B. Horton, OD, MD, who served as working group chair and Christopher J. Brady, MD, MHS, and Jerry Cavallerano, OD, PhD, who served as cochairs. The writing committees were separated into seven different categories. They are as follows: 1.Clinical/operational: Jerry Cavallerano, OD, PhD (Chair), Gail Barker, PhD, MBA, Christopher J. Brady, MD, MHS, Yao Liu, MD, MS, Siddarth Rathi, MD, MBA, Veeral Sheth, MD, MBA, Paolo Silva, MD, and Ingrid Zimmer-Galler, MD. 2.Equipment: Veeral Sheth, MD (Chair), Mark B. Horton, OD, MD, Siddarth Rathi, MD, MBA, Paolo Silva, MD, and Kristen Stebbins, MSPH. 3.Quality assurance: Mark B. Horton, OD, MD (Chair), Seema Garg, MD, PhD, Yao Liu, MD, MS, and Ingrid Zimmer-Galler, MD. 4.Glaucoma: Yao Liu, MD, MS (Chair) and Siddarth Rathi, MD, MBA. 5.Retinopathy of prematurity: Christopher J. Brady, MD, MHS (Chair) and Ingrid Zimmer-Galler, MD. 6.Age-related macular degeneration: Christopher J. Brady, MD, MHS (Chair) and Ingrid Zimmer-Galler, MD. 7.Autonomous and computer assisted detection, classification and diagnosis of diabetic retinopathy: Michael Abramoff, MD, PhD (Chair), Michael F. Chiang, MD, and Paolo Silva, MD.

Telemedicine for Glaucoma: Guidelines and Recommendations

Background: Glaucoma is the leading cause of irreversible blindness worldwide. Access to glaucoma specialists is challenging and likely to become more difficult as the population ages. Introduction: Using telemedicine for glaucoma (teleglaucoma) has the potential to increase access to glaucoma care by improving efficiency and decreasing the need for long-distance travel for patients. Results: Teleglaucoma programs can be used for screening, diagnostic consultation, and long-term treatment monitoring. Key components of teleglaucoma programs include patient history, equipment, intraocular pressure measurement, pachymetry, anterior chamber imaging/gonioscopy, fundus photography, retinal nerve fiber layer imaging, medical record and imaging software, and skilled personnel. Discussion: Teleglaucoma has tremendous potential to improve patient access to high-quality cost-effective glaucoma care. Conclusions: We have reviewed some special considerations needed to address the complexity of providing guideline-concordant glaucoma care.

Repeatability and agreement of intraocular pressure measurement among three tonometers

BACKGROUND

Elevated intraocular pressure (IOP) is one of the causes of irreversible optic nerve head damage and visual field loss. It is often measured with applanation tonometers but the use of rebound tonometry devices has been proposed as an alternative to assess IOP. Rebound tonometers have also been proposed as a method for patients to measure their own intraocular pressure (that is, self-tonometry). The purpose of this study was to determine the intrasession repeatability and the agreement of the IOP measurement with two rebound measuring principle tonometers, ICare ic100 and ICare Home with Perkins tonometer.

METHODS

This study involved 27 healthy volunteers (18 to 30 years old). We performed three consecutive IOP measurements with ICare Home, ICare ic100, and Perkins. The means of the three measurements from each device were calculated. Repeatability and agreement were defined according to the British Standards Institute and the International Organization for Standardization. The agreement was assessed using the method described by Bland and Altman, where 95 per cent of the differences or limits of agreement were between 1.96 standard deviations of the mean difference.

RESULTS

All tonometers showed close measurements (Perkins 15.34 ± 3.45 mmHg, range 10.00-24.00; ICare ic100 15.40 ± 4.06 mmHg, range 9.67-23.33; and ICare Home 14.22 ± 4.72 mmHg, range 7.33-24.00). The co-efficient of variation (CV) and within-subject standard deviation (Sw) was low for ICare ic100 and Perkins (close to 6.30 per cent and one) with higher values for ICare Home (CV = 9.55% and Sw = 1.33). The intraclass correlation co-efficient showed values higher than 0.96 for all tonometers. The difference between both rebound tonometers was statistically significant (p = 0.03).

CONCLUSION

The ICare ic100 tonometer provides repeatable IOP measurements close to the measurements of the Perkins IOP (good agreement); however, ICare Home provides less repeatable values, showing worse agreement with the Perkins tonometer in healthy subjects.

Comparison of Three Different Tonometers in Eyes with Angle Closure

SIGNIFICANCE

Precise measurement of intraocular pressure (IOP) is essential when diagnosing and managing glaucoma. We compared the IOP readings of three different tonometers and analyzed agreement among tonometers in eyes with high IOPs.

PURPOSE

The purpose of this study was to compare the IOP readings obtained using a Goldmann applanation tonometer (GAT), a rebound tonometer (RT), and a Tono-Pen (TP) in angle-closure eyes with elevated IOP before and after medical IOP-lowering therapy.

METHODS

Twenty-five eyes of 25 patients with angle closure and IOPs of greater than 30 mmHg were enrolled. Intraocular pressure was measured using RT (iCare Pro), TP (Tono-Pen XL), and GAT before and after medical treatment. The mean IOP readings of the tonometers were compared before and after treatment. The agreement among the tonometers was assessed via Bland-Altman analysis.

RESULTS

The measurements from 22 eyes of 22 patients were suitable for statistical analyses. Before medical treatment, the mean TP-IOP was significantly lower than the mean GAT-IOP (44.0 ± 10.3 vs. 50.4 ± 8.9 mmHg, respectively; P < .001), but no significant difference was evident between the RT-IOP and the GAT-IOP (50.8 ± 10.9 vs. 50.4 ± 8.9 mmHg, respectively; P = .79). After IOP-lowering treatment, the mean GAT-IOP (14.9 ± 4.7 mmHg) did not differ from either the mean RT-IOP (15.6 ± 4.4 mmHg) or the mean TP-IOP (15.4 ± 5.0 mmHg; P = .05 and P = .18, respectively). The random measurement error among tonometers was greater for high IOP readings.

CONCLUSIONS

Compared with RT or GAT, TP underestimated IOP in angle-closure eyes with a GAT-IOP of greater than 30 mmHg. Intraocular pressure reading agreement among the three tonometers was lower in eyes with high IOP.

Home monitoring for glaucoma

Glaucoma services are overwhelmed and struggling to accommodate current demand. Reducing the need for hospital based services would improve our ability to see those most at risk of vision loss, which could both reduce demand and improve patient outcomes. Digital technologies that provide opportunities for home monitoring of glaucoma progression have potential to contribute to solve these challenges and, potentially, improve glaucoma care. This article will review the literatures of well-established technologies that support home monitoring for glaucoma, specifically home tonometry (with rebound tonometry) and perimetry with Moorfields Motion Displacement Test and Melbourne Rapid Field.

Self-monitoring of intraocular pressure using Icare HOME tonometry in clinical practice

Purpose: To determine the value of self-monitoring of diurnal intraocular pressure (IOP) by Icare Home rebound tonometer in patients with glaucoma and ocular hypertension.

Methods: Patients with open-angle glaucoma or ocular hypertension, controlled IOP at office visits, and at least 3 years of follow-up in the glaucoma clinic were included. Progression of glaucoma was based on medical records and defined by documented structural and/or visual field change. Patients were trained to correctly perform self-tonometry and instructed to measure diurnal IOP in a home setting for 3 days. IOP characteristics (mean, peak IOP, fluctuation of IOP as range, and SD of IOP) were documented and compared between the progressive and stable eyes.

Results: Ninety-four patients (50 females) with a mean (SD) age of 57.1 (14.7) years were included. Among the 94 eyes from 94 subjects, 72 (76.6%) eyes had primary open-angle glaucoma, ten (10.6%) had pigmentary glaucoma, four (4.3%) had exfoliative glaucoma, and eight (8.5%) eyes had ocular hypertension. Thirty-six eyes showed progression and 58 eyes were stable. Patients with progression were older than those with stable disease (mean (SD) 65.8 (8.4) years vs 51.7 (15.3) years, P<0.001). The progression group had higher average IOP (mean (SD) 15.8 (4.0) mmHg vs 13.3 (3.7) mmHg, P=0.002), peak IOP (mean (SD) 21.8 (5.8) mmHg vs 18.6 (4.8) mmHg, P=0.01), and greater IOP fluctuation range (mean (SD) 11.6 (4.8) vs 9.1 (3.5) mmHg, P=0.011) compared to non-progression group.

Conclusion: Self-monitoring of IOP using Icare Home tonometry provides more complete data on variability of IOP to assist in the management of glaucoma.

Diurnal and 24-h Intraocular Pressures in Glaucoma: Monitoring Strategies and Impact on Prognosis and Treatment

The present review casts a critical eye on intraocular pressure (IOP) monitoring and its value in current and future glaucoma care. Crucially, IOP is not fixed, but varies considerably during the 24-h cycle and between one visit and another. Consequently, a single IOP measurement during so-called office hours is insufficient to characterize the real IOP pathology of a patient with glaucoma. To date IOP remains the principal and only modifiable risk factor for the development and progression of glaucoma. Only by evaluating IOP characteristics (mean, peak and fluctuation of IOP) at diagnosis and after IOP-lowering interventions can we appreciate the true efficacy of therapy. Unfortunately, a major limiting factor in glaucoma management is lack of robust IOP data collection. Treatment decisions, advancement of therapy and even surgery are often reached on the basis of limited IOP evidence. Clearly, there is much room to enhance our decision-making and to develop new algorithms for everyday practice. The precise way in which daytime IOP readings can be used as predictors of night-time or 24-h IOP characteristics remains to be determined. In practice it is important to identify those at-risk glaucoma patients for whom a complete 24-h curve is necessary and to distinguish them from those for whom a daytime curve consisting of three IOP measurements (at 10:00, 14:00 and 18:00) would suffice. By employing a staged approach in determining the amount of IOP evidence needed and the rigour required for our monitoring approach for the individual patient, our decisions will be based on more comprehensive data, while at the same time this will optimize use of resources. The patient’s clinical picture should be the main factor that determines which method of IOP monitoring is most appropriate. A diurnal or ideally a 24-h IOP curve will positively impact the management of glaucoma patients who show functional/anatomical progression, despite an apparently acceptable IOP in the clinic. The potential impact of nocturnal IOP elevation remains poorly investigated. The ideal solution in the future is the development of non-invasive methods for obtaining continuous, Goldmann equivalent IOP data on all patients prior to key treatment decisions. Moreover, an important area of future research is to establish the precise relationship between 24-h IOP characteristics and glaucoma progression.

Home tonometry in childhood glaucoma: clinical indications and physician and parental attitudes

Home rebound tonometry is a beneficial tool for the management of childhood glaucoma, yet is not commonly used. In this study, 29 childhood glaucoma patients were recruited for twice daily home intraocular pressure (IOP) monitoring using an Icare rebound tonometer. Home rebound tonometry data prompted and/or validated glaucoma-related surgery in 16 patients (55%) and medication change in 22 patients (76%). According to survey responses, 84% of parents or patients (n = 83) would be interested in home tonometry, and 80% of physicians (n = 48) agreed that home tonometry would improve their ability to manage patients; however, only 14% of physicians currently lend tonometers for this purpose, largely due to financial concerns.

Icare® rebound tonometers: review of their characteristics and ease of use

The rebound tonometer has a unique mechanism for measuring intraocular pressure (IOP) and has become popular worldwide due to its ease of use. The most notable advantages are the lack of an air-puff and need for topical anesthesia, ease of operation and transport, and the ability to use it with children. Four rebound tonometers (Icare® TA01i, Icare PRO, Icare HOME, and Icare ic100) are currently available for clinical examination. It is important to understand the characteristics of each tonometer and select the most appropriate one because the IOP values and the purpose of measurement are different. In this review, with the goal of improving the understanding of a range of tonometers, the issues with each device are discussed.

Twenty-four hour intraocular pressure measurements and home tonometry

PURPOSE OF REVIEW

IOP is the only treatable risk factor contributing to glaucoma and most management and treatment of glaucoma is based on IOP. However, current IOP measurements are limited to office hours and control of glaucoma in many patients would benefit from the ability to monitor IOP diurnally so as not to miss abnormal pressures, which occur outside of office hours Consequently, to improve patient care, the ability to enable accurate and minimally disruptive diurnal IOP monitoring would improve caring for these patients.

RECENT FINDINGS

The studies we selected for this review can be divided into three categories: self-/home-tonometry, continuous invasive intraocular pressure measurements, and continuous noninvasive ocular measurements.

SUMMARY

The desire to obtain better insight in our patients' true diurnal IOP has led to the development of home-tonometers, in addition to extraocular and intraocular continuous pressure measurement devices. All of the devices have respective advantages and disadvantages, but none to date completely fulfills the goal of providing a true diurnal IOP profile.Video abstracthttp://links.lww.com/COOP/A27.

Diurnal Intraocular Pressure Fluctuations with Self-tonometry in Glaucoma Patients and Suspects: A Clinical Trial

SIGNIFICANCE

This article shows that self-tonometry can provide robust measures of diurnal intraocular pressure (IOP) and also detect changes to IOP in response to treatment within a short period of monitoring. These advances in IOP monitoring may contribute to improved management of glaucoma patients and suspects.

PURPOSE

The aim of this study was to prospectively investigate the utility of rebound self-tonometry performed over several weeks for detecting diurnal IOP fluctuations in glaucoma patients and suspects and also initial response to topical treatment in glaucoma patients.

METHODS

Forty patients were recruited following glaucoma-specific examination. Subsequent to successful training with the iCare HOME tonometer, patients were instructed to measure IOP, in a sitting position, four times a day over 4 to 6 weeks. Date, time, laterality, and IOP downloaded from the tonometer and clinical examination data, including applanation IOP and corneal thickness, were analyzed. A user satisfaction survey was also administered at study completion. t Test and analysis of variance were used to compare groups and IOP across days. Pearson correlation was used to compare measurements to Goldmann applanation tonometry and IOP measurements from the first day/s to the overall mean IOP.

RESULTS

Twenty-seven patients (18 suspects and 9 glaucoma patients) completed data collection. Patients self-measured IOP on 118 (±29) occasions for 40 (±7.4) days. Two dominant patterns of fluctuation were revealed: peak IOP upon awakening (n = 11) and at midday (n = 13). Diurnal IOP measured in the first 7 days showed strong correlation to diurnal IOP across the entire study period (r = 0.82, P < .0001). Within 24 hours of treatment commencement (latanoprost 0.005% ophthalmic solution), IOP reduced from 23.9 (±5.2) to 16.1 (±2.6) mmHg. Overall, patients rated the instrument as easy to use, although difficulties with correct alignment were expressed.

CONCLUSIONS

Rebound self-tonometry demonstrated utility for measuring diurnal IOP fluctuations in most patients, hence enhancing management of patient with or at risk of developing glaucoma.

High Altitude-associated Changes in Intraocular Pressure Abrogated by Trabeculectomy

PURPOSE

To highlight the effect of ascent to high altitude on intraocular pressure (IOP) in a patient with primary open-angle glaucoma, who had previously undergone trabeculectomy in 1 eye.

METHODS

Case report.

RESULTS

A 66-year-old mountaineer with primary open-angle glaucoma and previous right trabeculectomy performed self-tonometry using a rebound tonometer (Icare HOME) before and during an expedition in the Himalaya. In the nonoperated eye, there was a statistically significant increase in IOP as the patient ascended to 5000 m over 8 days (R=0.790, P=0.001), consistent with recent literature. IOP increased by 1.73 mm Hg with each 1000 m increase in altitude. In the trabeculectomized eye there was no significant increase in IOP (R=0.219, P=0.172).

CONCLUSIONS

Filtration surgery may be protective against IOP fluctuations associated with ascent to high altitude. Self-tonometry complements standard glaucoma care by providing opportunities for IOP monitoring outside office hours and in remote locations.

Monitoring daily intraocular pressure fluctuations with self-tonometry in healthy subjects

PURPOSE

To evaluate the accuracy of the intraocular pressure (IOP) measured by healthy subjects with icare^® Home and to observe the IOP fluctuation and pattern of IOP fluctuation in healthy subjects over three consecutive days.

METHODS

Sixty healthy subjects were recruited to the study. IOP was measured by the subjects themselves and by study staff using icare^® Home tonometers on visits 1 and 2, as well as by study staff using Goldmann applanation tonometry (GAT). Furthermore, the subjects measured their IOP at home for three consecutive days.

RESULTS

Twenty-three per cent of the study eyes were excluded in the statistical analysis due to dropout or non-compliance to the schedule. Approximately 70% of the icare^® Home measurements were within 3 mmHg of the GAT measurements. Ten to 16% of the study eyes had IOP peaks outside office hours. Sixty-three per cent of the study eyes had different IOP patterns on consecutive days.

CONCLUSION

Rebound self-tonometry appears to be accurate and could be used to monitor short- and long-term IOP variations. The difference between IOP patterns on consecutive days raises questions as to the certainty of a single IOP measurement as a measure of treatment effect.

Agreement of patient-measured intraocular pressure using rebound tonometry with Goldmann applanation tonometry (GAT) in glaucoma patients

This study aims to determine the agreement of patient-measured intraocular pressure (IOP) using rebound tonometry with ophthalmologist-measured IOP using Goldmann applanation tonometry (GAT). Fifty-three glaucoma patients used rebound tonometry (Icare ONE, Icare Finland Oy., Finland) to measure their own IOP in ambient environments for 1 week, 5 times per day. Clinic IOP measurements were performed by ophthalmologists using GAT and by patients using rebound tonometry on examination days 1, 4 and 7 of the same week. The agreement between the two tonometries was evaluated by modified Bland-Altman plots and intra-class correlation coefficient (ICC) was determined. Differences in ICCs of them among the three examination days were evaluated by bootstrap resampling analysis. Respective within-measurement ICC of GAT and rebound tonometry were 0.98 and 0.94 on Day 1, 0.98 and 0.93 on Day 4, and 0.96 and 0.92 on Day 7. In a modified Bland-Altman plot, the mean difference ±1 standard deviation (SD) between the two tonometries was 0.15 ± 0.65 mmHg (p = 0.682). Between-measurement ICC were 0.66, 0.76 and 0.73 on the 3 examination days. There was no significant difference among ICCs. In conclusion, patient-measured IOP using rebound tonometry and ophthalmologist-measured IOP using GAT demonstrate good agreement.