Mean length of preclinical detectable phase of glaucoma is over 10 years

The mean length of the preclinical detectable phase (PCDP) of open-angle glaucoma is estimated to be over 10 years, according to a study published online Nov. 23 in JAMA Ophthalmology.

Johan Aspberg, M.D., from Lund University in Malmö, Sweden, and colleagues estimated the mean PCDP for open-angle glaucoma in a large population-based screening, including 32,918 participants aged 57 to 77 years.

The prevalence of newly detected cases at the screening, incidence of new cases after the screening, and expected clinical incidence (number of new cases expected to be detected without screening) were assessed. The cohort included 2,029 patients.

The length of mean PCDP was calculated by two methods: dividing the prevalence of screen-detected glaucoma by clinical incidence, assuming 100 percent sensitivity for screening, and using a Markov chain Monte Carlo (MCMC) model simulation that derived the length of mean PCDP and sensitivity of screening simultaneously.

The researchers found that the mean age at screening was 67.4 years for the 1,420 screened patients. The mean length of the PCDP was 10.7 years for the whole study population by the prevalence/incidence method, and 10.1 years by the MCMC method.

"We have not tried to analyze whether screening is cost-effective, but our results suggest that screening for open angle glaucoma, if repeated, could be done with relatively long intervals, e.g., five years," the authors write.

Several authors disclosed financial ties to the pharmaceutical and medical technology industries.