Sir,

Exfoliation syndrome (XFS) is a systemic disorder of the extracellular matrix characterized by the accumulation of elastic microfibrils in which oxidative stress and a chronic low-grade inflammation is implicated in the pathogenesis.1, 2, 3 The purpose of this study was to evaluate the serum concentrations of CRP, a marker for systemic inflammation, in subjects with XFS and exfoliative glaucoma (XFG).

Case report

A total of 33 exfoliative subjects (14 subjects with XFG and 19 subjects with XFS) with a mean age of 69.5±11.6 years and 23 age-matched (mean age=67.3±10.5 years) control subjects were included in this study. A minimum sample size of 18 subjects was required to detect a clinically meaningful difference of 0.5 mg/dl with an alpha error of 0.05 and power of 0.90. Serum CRP levels were determined using nephelometric assay. The mean serum CRP level of subjects with exfoliation (0.54±0.46 mg/dl) (XFS+XFG combined) was not significantly different (P=0.274) than that of healthy subjects (0.42±0.28 mg/dl). In addition, the mean age, gender ratio, and serum CRP concentrations were similar between subjects with XFS, XFG, and controls (Table 1). Coronary artery disease and hypertension was present in 15.2% and 27.2% of exfoliative patients, respectively (Table 1).

Table 1 Clinical parameters and serum CRP concentrations in different groups included in the study
Full size table

Comment

The interaction of co-pathogenetic mechanisms such as oxidative stress, tissue hypoxia, and release of growth factors (ie, TGF-β1) is believed to be associated with chronic low-grade inflammation and propensity to excessive inflammation following intraocular procedures associated with breakdown of the blood-aqueous barrier.1, 2 The presence of inflammation in XFS has been further substantiated by elevated aqueous interleukin-6 levels in early stages of XFS and the identification of C1q component of the complement system within the microfibrillar aggregates.3, 4 In addition, XFS has been shown to be correlated with age-related macular degeneration, another disorder with underlying inflammatory mechanisms in which serum CRP levels have been found to be elevated.5

Our results revealed that serum CRP levels were not elevated in patients with XFS and XFG. In a recent study, serum levels of CRP in XFS and XFG were found to be similar to that of healthy controls.6 In that study, all subjects with a history of vascular disease including hypertension and coronary artery disease were excluded; however, exclusion of subjects with vascular disease may potentially be representative of patients with a milder phenotypic disorder. Nonetheless, on the basis of our results and those of Yuksel et al,6 we suggest that XFS-associated inflammation is not able to induce hepatic synthesis of CRP and is associated with a limited local and subclinical inflammatory reaction in involved tissues.