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Jason Ho, Sally Ameen, Laura Crawley, Eduardo Normando, M Francesca Cordeiro, Philip Bloom, Faisal Ahmed; Key predictors of visual field test reliability. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2632.
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© ARVO (1962-2015); The Authors (2016-present)
Patient reliability is of key importance in helping clinicians interpret visual fields (VF) for accurate glaucoma diagnosis and progression monitoring. We investigate which patient factors predict poor VF test reliability according to standard indices of Fixation loss (FL), False-negatives (FN) and False-positives (FP).
We conducted a 14-year (1998-2012) retrospective review of 34304 Humphrey 24-2 visual field tests from 8532 patients at a single tertiary referral centre. Corresponding clinical data was collated from a Medisoft database. Each VF test was analysed individually. Standard criteria were used to assess VF test reliability: FL<25%, FP<25% and FN<33%. Multivariate binomial logistic regression analysis determined which clinical factors correlate with VF reliability. Subgroup analysis was performed for: (i) patients with >3 VF tests and (ii) VF tests with recorded visual acuity data.
26.25% of VFs were unreliable. Mean patient age was 65. Standard reliability indices (FL, FN, FP) independently demonstrate good correlation (p=0.00). Age, greater mean deviation, an established glaucoma diagnosis, using >1 glaucoma medication and having fewer prior VF tests, all negatively correlate with the likelihood of VF test reliability (p<0.03). VF tests performed at shorter intervals are less likely to be reliable (Odds Ratio 1.03, p=0.015). Sex, presence of cataract and ARMD are not significant predictors. Worse visual acuity is independently associated with more unreliable VF tests.
Older patients with worse vision, more advanced glaucoma and fewer prior VF tests are less likely to yield reliable VF results and testing at shorter intervals does not necessarily increase reliability. These factors can aid clinical decisions to improve resource utilisation of visual field tests in busy glaucoma practices.
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