Oct. 8, 2007 -- A chemical marker of inflammation may be connected to the leading cause of vision loss in Western countries.
Dutch researchers reported that news today in the Archives of Ophthalmology.
They studied the inflammation marker C-reactive protein (CRP) and age-related macular degeneration (AMD), in which the macula (part of the retina) gradually fails, hampering central vision.
High levels of CRP in the blood may make AMD more likely, according to the researchers, who included Sharmila Boekhoorn, MD, PhD, of Erasmus Medical Center in the Dutch city of Rotterdam.
If that finding is confirmed in other studies, checking someone's CRP level may gauge their odds of developing AMD, the researchers suggest.
CRP and AMD Study
For more than seven years, Boekhoorn's team followed some 4,600 Rotterdam residents aged 55 and older.
When the study started, participants provided blood samples and were screened for age-related macular degeneration. None had AMD at the time. They were screened for AMD three more times during the study.
When the study ended, 561 participants had developed early-stage AMD and 97 others had developed late-stage AMD.
Those with high blood levels of C-reactive protein at the study's start were the most likely to have at least early-stage AMD, according to Boekhoorn and colleagues.
For instance, participants with the highest CRP levels at the study's start were 40% more likely to develop early-stage AMD during the study, compared to those with the lowest initial CRP levels.
The same may be true for late-stage AMD, but it was hard to be sure of that, given the relatively small number of participants who developed late-stage AMD during the study.
The findings don't prove that C-reactive protein causes AMD. But the results didn't change when the researchers considered other AMD risk factors including age, smoking, and type 2 diabetes.