1. Use of the ICare Home Rebound Tonometer for home self-monitoring of intraocular pressure in a Singaporean population
Jeanne Joyce OGLE1, Wai Cheng SOO HOO1, Angela Peck Hoon LIM1, Leonard Wei Leon YIP1
1 National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore
Introduction
Results […continued]
Management of glaucoma is largely based on measurement of intraocular pressure (IOP) with treatment aimed at lowering IOP.
Unfortunately ‘snap-shot’ IOP measurement in the glaucoma clinic at a given point of time is not at all reflective of IOP trends throughout the day. Short of continuous IOP monitoring, intermittent home self-monitoring of IOP over a period of time could possibly provide invaluable information on IOP trends. This would give clinicians a better understanding of the individual patient, thus facilitating better management of the disease.
On univariate analysis, there was no statistically significant impact of age, gender, central corneal thickness, visual acuity or severity of glaucoma on the accuracy of the patient’s ICare readings.
Intraclass correlation coefficient (ICC) between ICare Home readings obtained by the study team and the patients at the first visit was (95% confidence interval (CI) ) for the right eye, and (95% CI, ) for the left eye.
ICC at the final visit was 0.77 (95% CI, ) for the right eye, and (95% CI, ) for the left eye.
There was reasonably good agreement between the study team and patient readings, especially at the final visit.
Test-retest variability did not show any significant trend over the 7-day period for either eye.
From questionnaire responses 65% of patients agreed the device is easy to use although only 37% could get the reading at their first attempt. 89% of the patients would recommend the device to other glaucoma patients.
Objectives
Our primary objective is to establish whether Singaporean patients can perform accurate and reliable home self-monitoring of their IOPs using the ICare Home Rebound Tonometer.
Methodology
20 patients attending glaucoma subspecialty clinics were enrolled.
The study team first measured the patient’s IOPs using the Goldmann applanation tonometer (GAT) and the ICare Home. These readings were recorded to be compared.
The patients were then trained to use the ICare Home and their readings recorded to be compared with the study team’s readings.
The ICare Home device was then loaned to the patients for a period of 7 days.
During the loan period, patients measured their IOPs for both eyes twice a day, taking 3 readings each time.
A week later, GAT & ICare readings were again taken by the study team and the patients. All the IOP readings over the week and at the final visit were downloaded and analysed.
Bland-Altman difference analysis was used to assess the agreement between GAT and ICare Home readings taken by the study team.
Intraclass correlation (ICC) compared the ICare Home measurements by the study team and the patient.
Test-retest variability for the patient's readings over the 7-day period were analysed by taking the standard deviation of the 6 readings taken per day.
A questionnaire was also administered at the conclusion of the study to assess the patient's experience with the device.
Discussion
Our study shows that a fair proportion of our patients can be trained to use the ICare Home device with fairly accurate readings obtained after just one training session and this is not limited by age, severity of glaucoma or visual acuity. There does appear to be a bit of a learning curve despite the test-retest variability demonstrating no significant trend in the readings taken over a 7-day period as there is some improvement in accuracy at the end of the loan period as compared to the initial session. Granted the ICare Home slightly over-estimated IOP compared with GAT, but the overall trends recorded would still provide valuable information to the clinician. Perhaps more importantly, the device was well received by patients who agree that it is portable and easy to use.
Results
Conclusion
Singaporean patients are able to perform reasonably accurate self-tonometry using the ICare Home tonometer following a short period of training although readings are generally slightly over-estimated compared with GAT.
Reasonably good agreement was demonstrated between IOP readings obtained by the study team using the GAT and ICare Home with 95% of differences between the two measurement methods falling within the limits of agreement.
ICare Home readings were generally slightly higher for both eyes compared with GAT. Mean bias ranged from 1.7 to 2.3 mm Hg right eye, and 1.4 to 1.85 mm Hg left eye.
At the first visit, 13 patients (68%) could perform fairly accurate self-tonometry on their right eye (obtaining readings within 2mm Hg of the study team readings), and 11 patients (55%) on their left eye.
At the final visit, this increased to 14 patients (70%) for the right eye and 15 patients (75%) for the left eye.
References
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2. Abraham LM, Epasinghe NCR, Selva D et al. Comparison of the ICare rebound tonometer with the Goldmann applanation tonometer by experienced and inexperienced tonometrists. Eye 2008;22:
3. Asrani S, Chatterjee A, Wallace DK et al. Evaluation of the ICare Rebound Tonometer as a Home Intraocular Pressure Monitoring Device. J. Glaucoma 2011;20(2):74-79
4. Dabasia PL, Lawrenson JG, Murdoch IE. Evaluation of a new rebound tonometer for self-measurement of intraocular pressure. Br J Ophthalmol 2016;100(8):