Disease severity in newly diagnosed glaucoma patients with visual field loss: trends from more than a decade of data

Abstract

Purpose: Large archives of visual field (VF) records from automated perimetry are used to examine severity of vision loss at diagnosis in glaucoma patients over a 13 year period in England.

Methods: A total of 473 252 Humphrey VFs recorded at four regionally different glaucoma clinics in England were retrospectively examined. Patients were required to have a Humphrey mean deviation (MD) outside 95% normative limits in at least one eye and had at least two visits to the glaucoma clinic in a study period between the start of 1999 and the end of 2011. No other clinical data was considered. MD of the worse eye at the first hospital visit was used as an estimate of vision loss for a patient at diagnosis; proportion of patients categorised as having 'early' (better than -6 dB) or 'advanced' (worse than -12 dB) VF loss were also calculated. Simple linear regression of MD against the date of first visit was used to estimate changes in vision loss at diagnosis over time.

Results: Median age, at the time of diagnosis, of the 25 521 patients included in the analysis was 67 (interquartile range 55-76) years. Average level of glaucoma vision loss at diagnosis, in those patients presenting to secondary care with a VF defect, improved by an average 0.11 dB per year over the study period (95% confidence interval: 0.08-0.13 dB per year; p < 0.0001). Percentage of patients with 'advanced' VF loss in at least one eye at diagnosis changed from 30% (1999-2001) to 21% in (2009-2011) (p < 0.0001).

Conclusions: Severity of vision loss at the point of glaucoma detection, in those patients diagnosed with a VF defect, is improving over time in England. Nevertheless, the improvement is modest and large numbers of patients still present at glaucoma clinics with significant vision loss in at least one eye. Large scale digital VF data can be used to help monitor and audit health service delivery of glaucoma.

Keywords: glaucoma detection; glaucoma referral; trend analysis; visual field.