On the Feasibility of Accelerating Glaucoma Clinical Trials Using Portable Perimetry.

PURPOSE

To model whether more frequent (weekly, monthly) visual field (VF) assessments using portable "home" perimetry might more quickly detect glaucoma progression in a clinical trial context.

DESIGN

Cross-sectional with additional simulations

PARTICIPANTS

Forty patients (78 eyes; n = 21 healthy, n = 16 glaucoma suspects, n = 41 manifest glaucoma).

METHODS

Participants performed an interleaved sequence of 2 portable (Eyecatcher v3.0; EC3) and 2 reference (Humphrey Field Analzyer [HFA] SITA-Fast) VF tests (4 tests total per eye). Linear mixed modeling was then applied to one randomly selected eye per patient to mathematically predict the expected proportion of progressors detected by EC3/HFA over a 3-year period, given different testing regimens (from weekly to every 4 months), levels of variability, and underlying rates of true progression.

MAIN OUTCOME MEASURES

Test-retest variability and proportion of progressors detected.

RESULTS

The portable perimeter was significantly less reliable: the Bland-Altman 95% coefficient of repeatability for mean deviation (CoR) was 6.37 dB for EC3 and 4.25 dB for the HFA. Statistical simulations, however, predicted that this lower reliability would be offset by more frequent testing. Thus, modeling indicated one EC3 test per month would detect a higher proportion of slow (-0.5 dB/year), moderate (-1 dB/year), and fast (-2 dB/year) progressors compared to one HFA test every 4 months. Implications for trial sample sizes were also modeled, with the number of participants required to evidence a 20% reduction in baseline progression over 2 years (following a hypothetical intervention) predicted to decrease by 24.3%/36.3% with the addition of monthly/fortnightly home testing. There was no significant difference in mean test duration between the EC3 and HFA (226 vs. 225 seconds, P = 0.78), and participants rated the EC3 as somewhat easier to use (system usability scale; P = 0.004).

CONCLUSIONS

Home VF assessments, despite poorer reliability than current reference standard ("in-clinic") devices, would allow faster or greater detection of glaucoma progression via an increased frequency of testing, and could reduce the sample size requirements of future clinical trials. Implications on duration, access and overall cost are discussed. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.