Abstract
Purpose :
Recent reports suggest that patients with primary open-angle glaucoma (POAG) may have lower levels of intracranial pressure (ICP). Pathogenically, a low ICP creates a translaminar pressure gradient that may be associated with the eventual development of POAG. The converse of this postulate seems worth exploring - does elevated ICP protect against glaucomatous damage to the optic nerve? An idiopathic intracranial hypertension (IIH) population and that population’s eventual development of glaucoma may afford a prism to explore the effects of elevated ICP on POAG.
Methods :
A retrospective epidemiological study was conducted to compare prevalence of POAG in IIH patients with that in the total Montefiore population. Inclusion criteria were the diagnosis of IIH or POAG during the study period (7/1997 – 7/2014). We assembled three cohorts – (1) POAG (N=12,387, avg. age 65.3, M:F 1:1.6) (2) IIH (N=961, avg. age 31.3, M:F 1:6.5), (3) all Montefiore patients (N=1,466,554, avg. age 41.7, M:F 1:1.3). We also assembled age-adjusted cohorts >40 for each group – POAG (N = 11,908, avg. age 68, M:F 1:1.6), IIH (N = 353, avg. age 48.4, M:F 1:7.5) and all Montefiore patients (N = 646,698, avg. age 56.4, M:F 1:1.5). We analyzed data with logistic regression analyses.
Results :
The overall prevalence of POAG in the total Montefiore patient population vs. in the IIH cohort was 0.84% vs. 0.21%; a difference that was statistically significant (p=0.030), odds ratio = 0.250, 95% CI (0.063-0.991). Within the age-adjusted cohorts the prevalence of POAG in all patients vs. the IIH cohort was 1.84% vs. 0.28% (p=0.026). Logistic regression analysis, controlling for age, dampened the protective effects of elevated ICP, odds ratio = 0.517, 95% CI (0.129-2.075).
Conclusions :
The effects of ICP upon the eventual development of POAG are difficult to disaggregate as the age of incidences of each disease, while overlapping, have different peaks. IIH is diagnosed at one point in time and a continuingly elevated ICP is not expected to persist for many years after diagnosis. It is not readily known if IIH patients maintain higher than normal ICPs in later decades. That said, there is enough evidence to suggest that low ICP is a risk factor for the development of POAG and growing evidence that elevated ICP may be a protecting variable for its development. Further experimental studies which correlate ICP and its effects on disc tissue are warranted.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.