Abstract
Purpose: :
To evaluate long term changes in the visual field in an older Australian population with glaucoma.
Methods: :
The Blue Mountains Eye Study examined 3654 participants over 49 years at baseline (1992-4) and re-examined the cohort 5, 10 and 15 years later. Prevalent and incident cases of open-angle glaucoma (OAG) were evaluated with the Humphrey visual Field Analyzer (HFA) at each visit. Velocity of progression was determined from changes in mean deviation (MD) over each follow-up interval and expressed as decibels per year (dB/yr). Linear regression was performed using known glaucoma risk factors as co-variates.
Results: :
OAG was found in 108 participants at baseline of which 101 had HFA data and half were receiving treatment. By the 10 year examination, 78 of the 108 had died, replaced by 75 incident glaucoma cases. After excluding participants with less than two sets of examination data, longitudinal visual field data was available in 207 eyes of 104 participants with OAG. Mean MD for eyes with glaucoma was -8.05dB at baseline. For incident eyes, mean MD was -9.01dB at the 5 year and -8.71dB at the 10 year examinations. Of eyes with an MD>-10dB at baseline, more than two-thirds had progressed to <-10dB by 10 years. Eyes with OAG at baseline progressed at a mean of 0.77dB/year over 10 years. Fellow eyes not fulfilling the criteria for OAG progressed at 0.63dB/year over the same period. Similarly, eyes with incident OAG at the 10 year examination had progressed at a mean of 0.74dB/year over the prior 10 years, while fellow eyes progressed at 0.61dB/year. The maximum 5-year progression rate was 5.59dB/year. 10% of eyes progressed more than 15dB over 10 years. Maximum 5-year velocity of progression was significantly lower for eyes of participants on glaucoma treatment at baseline (0.71dB/yr vs 0.30dB/year).
Conclusions: :
These data show that the population-based prevalence of OAG is relatively constant over a long time period, with incident cases replacing those who have died. Annualized estimates of velocity of visual field progression in glaucoma were similar across time periods and similar to estimates from other studies. Although the mean progression rate was modest, individual rates varied widely with 10% progressing to advanced damage over 10 years. Glaucoma treatment at baseline was associated with slower progression.
Keywords: clinical (human) or epidemiologic studies: natural history • perimetry • visual fields