Antiangiogenic activity in tears: presence of pigment-epithelium-derived factor. New insights and preliminary results

Abstract

Background/purpose: Pigment-epithelium-derived factor (PEDF) is of major importance to prevent neovascularization of the retina. Recently found to occur in the cornea and conjunctival tissue, its presence in tears has this far not been reported. Initial results, based on the analysis of diluted tear fluid samples, even indicated the absence of this factor in human tears. Considering the clinical importance of PEDF as regulator of corneal vascularization, we investigated undiluted human tears.

Methods: Samples of 18 healthy individuals were collected and analyzed using a commercial ELISA. Samples were also collected from 5 patients with pterygium and as a positive control 2 samples of subretinal fluid from patients following retinal detachment surgery.

Results: PEDF concentrations were below the detection limit (i.e. <0.1 ng/ml) in the majority of samples from the healthy individuals. However, PEDF was discovered in 3 of the samples taken, with significant concentrations of 2, 32 and 53 ng/ml. In the group of 5 patients with pterygium, there were no detectable concentrations of PEDF.

Conclusion: PEDF may be found in measurable amounts in human tear fluid of healthy individuals and may therefore play a role in the effects and regulation of PEDF at the ocular surface.