Abstract
Purpose: :
To estimate visual field (VF) loss in patients during their predicted lifetime receiving standard clinical care in glaucoma clinics in England.
Methods: :
Over 120,000 Humphrey 24-2 SITA VFs recorded in three regionally different glaucoma clinics/services in England (Cheltenham, London and Portsmouth) in the last decade were retrospectively investigated. A sample of patient VF series were considered, excluding those with too few VFs (less than 6) or insufficient follow-up (less than 3 years). Mean deviation (MD) at the baseline VF (‘diagnosis’) and MD loss during predicted remaining lifetime, using a linear rate of MD deterioration in dB/year and residual life expectancy tables, were calculated.
Results: :
A sample of 4636 VF series from patients with a median age of 67 (interquartile range [IQR]: 58 to 73) years were analysed. For these VF series, median MD at ‘diagnosis’ was -2.8 dB (IQR: -6.9 to -0.8 dB) and median amount of further MD lost during predicted remaining lifetime was -2.4 dB (IQR: -6.1 to 0.0 dB). In the patient’s ‘better’ eye, median MD predicted to be lost during remaining lifetime was -2.0 dB (IQR: -5.8 to 0.0 dB). Seven percent (95% confidence interval: 6 to 8%) of patients were at risk of developing MD worse than -20 dB in the ‘better’ eye in their predicted remaining lifetime; MD in the ‘better’ eye in these patients at ‘diagnosis’ (median: -5.3 [IQR: -9.0 to -2.4] dB) was significantly different to the whole cohort (median: -1.8 [IQR: -4.0 to -0.4] dB; p<0.001).
Conclusions: :
In this population, 50% of patients receiving standard clinical care are estimated to lose a total of less than 2 dB of MD in their ‘better’ eye during predicted lifetime after diagnosis; the average patient has lost more than half of all the VF they are destined to lose prior to diagnosis. A small but significant proportion of patients under clinical care, typically with worse MD at diagnosis, are estimated to be at risk of disabling VF loss during their predicted lifetime. These findings illuminate the need for earlier diagnosis in glaucoma.
Keywords: visual fields • clinical (human) or epidemiologic studies: health care delivery/economics/manpower • perimetry