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Editors Selection IGR 13-2
Clinical Examination Methods: Function: Home monitoring
Comment by Robert Fechtner on:
74061 Can Home Monitoring Allow Earlier Detection of Rapid Visual Field Progression in Glaucoma?, Anderson AJ; Bedggood PA; George Kong YX et al., Ophthalmology, 2017; 124: 1735-1742
Glaucoma progression, as measured by visual field testing, is a statistical event. A few fundamental principles are used to determine statistically significant change in the visual field. The first step is to establish a baseline. Then we need to know intra-test variability. And finally, we must determine and confirm that a test point or points are statistically significantly different from the baseline taking into consideration the variability. In a model where visual fields are tested once or twice yearly this can take several years. Even using the strategy of pointwise linear regression it requires several field tests to determine significant change over time.
For patients with "slow" glaucoma this may be acceptable. However, for patients with rapidly progressing glaucoma substantial vision might be lost over the period of time it takes to establish a sufficient number of fields required for statistical analysis. The authors raise the intriguing idea that frequent home testing might allow detection of progression over a much shorter period of time than office testing. A tablet-based perimeter (Melbourne Rapid Fields) can be used for self-testing at home. As an exploratory study, the authors used simulation methods to quantify benefits that might be expected from using frequent home monitoring. Subjects performed supervised tablet testing on two occasions two months apart to establish inter-test variability. Two in-office scenarios were simulated (six monthly and yearly testing).
Three home monitoring scenarios were simulated (weekly, fortnightly, and monthly testing). It took 2.5 years to achieve a sensitivity of 0.8 in the model of six monthly testing in the clinic. In contrast, home monitoring on a weekly basis achieved 0.8 sensitivity after only 0.9 years (at 46 weeks.) The weekly home testing model achieved specificity of 0.9 by 12 weeks.
In this simulation of tablet based home monitoring of visual fields, the results suggest that this technology could lead to earlier detection (and intervention) for rapidly progressing patients. The authors caution that the baseline testing upon which these simulations were created was conducted under controlled conditions and that prospective clinical trial is warranted. These simulations strongly suggest that frequent home monitoring is likely to improve our ability to detect rapid progression of glaucoma even with imperfect compliance. The cost benefits of home monitoring remain to be determined.
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