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.
. Purpose: To evaluate the effect of cataract on rarebit perimetry and the fovea test. Methods: Twenty‐five consecutive patients scheduled for cataract surgery (mean age 63.0 ± 7.9 years) were examined prior to and after cataract surgery with a complete ophthalmological examination. In addition, the rarebit perimetry (RBP) and the rarebit fovea test (RFT) were performed. Results: Best‐corrected visual acuity [BCVA, expressed in minimum angle of resolution (MAR)], RBP and RFT mean hit rate (MHR) improved significantly after cataract surgery. The relative pre–postsurgery difference was larger in the RFT [2.1 standard deviations (SDs)] compared to in BCVA (0.78 SDs). Seven patients had good BCVA (≤ 1.25) and RBP (83–99%) but low RFT (0–66%) before surgery. One patient with low preoperative BCVA (2.5) had a normal RFT (94%). Conclusion: Cataract influenced both the RFT and RBP test, albeit the former more than the latter. The influence of cataract on RFT results, even when visual acuity is decreased only moderately, has to be taken into account when evaluating foveal function in patients with cataract. The larger relative change in RFT compared to BCVA values is thought to indicate that RFT is more sensitive for the effect of cataract. Therefore, RFT appears to be a sensitive test for visual disturbance and can presumably provide additional information at the preoperative evaluation of the patient.
PEDF (pigment-epithelium-derived factor) is a member of the serpin family of protease inhibitors. It is considered to be an important regulator of human eye disease and is known to inhibit angiogenesis. We have therefore investigated the presence of PEDF in the subretinal fluid of patients with retinal detachment. Methods: Eighteen samples from SRF were collected from patients during retinal detachment surgery. Specific ELISA analysis was performed with specific IgG against human PEDF. Results: PEDF was detected in the subretinal fluid of all cases. The mean concentration of PEDF was 33.9 ng/ml (SD 23.7 ng/ml; range 5.3–74.7 ng/ml). The majority of samples had however a concentration of more than 22 ng PEDF/ml fluid. Conclusion: PEDF appears to be a constant component of the fluid accumulating in the subretinal space after retinal detachment. The known effects of PEDF, however, suggest that it may be involved in physiological processes of wound healing in the subretinal space.
The detection of pigment-epithelium-derived factor (PEDF) in corneal tissue has allowed greater understanding of the avascularity of corneal tissue. The ability of the cornea to maintain the avascular nature of this tissue, also referred to as the angiogenic privilege of the cornea, could be partly attributed to the presence of this factor. This privilege is severely impaired by various diseases of the ocular surface associated with inflammation and infection that are often followed by neovascularisation, which compromises the transparency of the cornea and results in visual impairment. The rapidly increasing insights into the basic mechanisms controlling neovascularisation, i.e. balance of growth factor activation and enzymatic activity, has most recently led to the development of large-scale use of specific antiangiogenic agents in the treatment of neovascular age-related macular degeneration (AMD). Focusing on the effects of vascular endothelial growth factor (VEGF), the use of such agents, including bevacizumab (Avastin®), a humanised anti-VEGF monoclonal antibody originally used in the treatment of metastatic colorectal cancer, has been investigated in corneal angiogenesis. PEDF is only one of the many factors involved in ocular angiogenesis. However, although it is only a small protein, it has strong antiangiogenic actions that are expressed in the retinal pigment epithelial (RPE) layer, as well as in other parts of the eye. There are specific characteristics that could designate a special role for PEDF in the regulation of avascularity in the eye. In this article, we focus on corneal angiogenesis and highlight the special features of this somewhat unexplored cytokine, outlining the current knowledge and possible role of PEDF in corneal neovascularisation.
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