Aqueous and serum β₂-microglobulin levels in patients with senile cataracts, and cataracts associated with uveitis or atopy

Abstract

β₂-Microglobulin (β₂ M) has been reported to be elevated in patients with a variety of neoplasms and inflammatory disorders, and is believed to be a sensitive although nonspecific marker for lymphocyte activation and/or proliferation. In order to investigate the role of inflammation in the pathogenesis of various types of cataract, the authors measured β₂M concentrations in the aqueous humor and serum of patients with senile cataracts (82 eyes), cataracts secondary to uveitis (16 eyes) and cataracts associated with atopic dermatitis (eight eyes). In addition, measurements were made in six patients with rhegmatogenous retinal detachment (RRD) and three patients with central retinal artery occlusion (CRAO) for comparison. The average aqueous β₂M was increased in eyes with uveitic cataracts (678 μg/1) and RRD (533 μg/1), when compared to eyes with senile cataracts (265 μg/1), atopic cataracts (309 μg/1) and CRAO (122 μg/1). However, comparison of β₂M to albumin aqueous-to-serum ratios (protein coefficient analysis) revealed that the aqueous β₂M elevation was specific in only uveitic cataracts, with the elevation in RRD being most likely due to breakdown of the bloodocular barrier. Higher aqueous β₂M concentrations were also found in cataracts with a posterior subcapsular cataract component, although this was related to a higher percentage of uveitic cataracts in this group. There was no statistically significant difference found in association with a past medical history of diabetes mellitus, hypertension or heart disease. These results are discussed in the context of the pathogenesis of cataract and the role of β₂M in inflammatory processes of the eye.

Key Words:

• β₂-Microglobulin
• senile cataract
• secondary cataract
• uveitis
• atopy