Examining visual field loss in patients in glaucoma clinics during their predicted remaining lifetime

Abstract

Purpose: To evaluate the proportion of patients in glaucoma clinics progressing at rates that would result in visual disability within their expected lifetime.

Methods: This retrospective study used visual field (VF) series of at least 3 years' duration from 3790 UK patients in glaucoma clinics calculating rates of loss for each eye using linear regression of mean deviation (MD) over time. Residual life expectancies derived from the UK Office of National Statistics actuarial tables for each patient were combined with these rates to estimate predicted MDs at end of expected lifetime. The proportion of patients projected to progress to visual impairment (MD: -14 dB or worse) or statutory blindness (MD: -22 dB or worse) in both eyes before end of expected lifetime was calculated.

Results: Only 3.0% (95% confidence interval [CI] 2.7%-3.4%) of patient eyes progressed at faster than -1.5 dB/year (n = 7149 eyes). Of those patients with both eyes followed, 5.2% (CI 4.5%-6.0%) were predicted to progress to statutory blindness, with a further 10.4% (CI 9.4%-11.4%) reaching visual impairment in their lifetime. More than 90% (CI 85.7%-94.3%) of patients predicted to progress to statutory blindness, had an MD worse than -6 dB in at least one eye at presentation.

Conclusions: This modeling exercise indicates that most patients in glaucoma clinics are not at high risk of progressing to statutory blindness. The likelihood of patients suffering impairment in their lifetimes is linked to VF loss at presentation, which illuminates the importance of reliably detecting significant VF defects in primary care.

Keywords: glaucoma; life expectancy; perimetry; visual fields; visual function.