Ciliary neurotrophic factor in patients with primary open-angle glaucoma and age-related cataract

Purpose To study the ciliary neurotrophic factor (CNTF) concentration in the aqueous humor (AH), lacrimal fluid (LF), and blood serum (BS) in patients with age-related cataract and primary open-angle glaucoma (POAG). Methods CNTF concentrations were studied in 61 patients with age-related cataract, 55 patients with POAG combined with cataract, and 29 healthy controls (one eye in each person). Preliminary experiments permitted us to extend the minimum quantifiable value of the CNTF Quantikine enzyme-linked immunosorbent assay (ELISA) kit to 2.5 pg/ml. Results The levels of CNTF in LF and BS did not differ in patients with cataract and controls. The CNTF concentration (pg/ml) in patients with POAG and cataract was lower than in patients with cataract (p<0.001) in AH (39.9±26.2 versus 57.2±25.6) and in LF (25.7±14.9 versus 39.9±18.0). The differences were not statistically significant for the CNTF level in BS (5.45±4.72 versus 5.96±4.92) and the AH/LF ratio (1.69±1.05 versus 1.58±0.70). In the patients with POAG, the AH level of CNTF correlated with the visual field index (Pearson's correlation coefficient r = 0.35, p = 0.01). A statistically significant decrease in the AH and LF concentrations of CNTF was observed in patients in all stages of POAG compared with the cataract group. This decrease was particularly prominent in patients with severe glaucoma. Compared to patients with combined early and moderate stages of disease patients with advanced glaucoma showed an insignificant reduction in the median CNTF concentration in AH and LF. The serum CNTF concentration did not show any dependence on the glaucoma stage. The CNTF concentration in the AH strongly correlated with the CNTF concentration in the LF (r=0.71, p<0.000). A formula was suggested to calculate the concentration of CNTF in AH based on the CNTF concentration in LF. Conclusions The CNTF concentration is reduced in the AH and LF of patients with POAG, especially in those with severe visual field loss. The CNTF concentration in AH and LF showed a strong correlation, and this phenomenon opens up new options for a noninvasive estimation of the CNTF concentration in AH. The CNTF concentration established in the AH, LF, and BS of patients with age-related cataract can serve as normative data for persons older than 50 years old.