Researchers Use Tear Samples of Scleroderma Patients To Gain New Insights Into How SSc Affects Eyes
A study was recently conducted to determine levels of vascular endothelial growth factor in the tears of patients with scleroderma. Vascular endothelial growth factor or VEGF has been found to play a major role in the development of new blood vessels in a number of diseases, including macular degeneration of the eye, diabetic retinopathy, retinopathy of prematurity and sickle cell retinopathy. In scleroderma, VEGF is believed to contribute to some of the eye complications related to the disease, including dry eye syndrome (DES), conjunctival telangiectasia, and filamentous keratitis.
Scleroderma or SSc (systemic sclerosis) is an autoimmune disease characterized by fibrotic changes in several organ systems, including the skin, heart, lungs, GI tract, and kidneys. The eyes are also affected by scleroderma, with many people developing dry eye syndrome and other eye conditions. The study, entitled “Vascular Endothelial Growth Factor in Tear Samples of Patients with Systemic Sclerosis” published in Mediators of Inflammation was designed to observe if there were elevations in VEGF in the tears of scleroderma patients that could account for some of the problems in vision that these patients experience.
One of the pitfalls of doing this kind of study is that very small samples of tears can be collected for evaluation, and patients with scleroderma produce tears at a decreased rate when compared to normal subjects. The secretion of tears is observed to be diminished by 67 percent in the scleroderma population. Researchers believe that this due to the fibrosis commonly associated with the disease. As a result, the collection of tears for the study was difficult and time-consuming.
The researchers measured the total protein concentration in the tears of scleroderma patients and found that they had concentrations of protein that were 42 percent higher than controls. Researchers attributed this to the fact that scleroderma patients exhibited a small tear volume, making protein concentrations artificially high. In addition, the level of VEGF was 20 percent less than in controls, also likely due to low tear volumes.
While the study did not show the expected increase in VEGF in scleroderma patients when compared to control participants, the authors believe that these results may not be accurate due to the inability to collect enough tear volumes so that an accurate sampling could be obtained. In spite of the unexpected results, the researchers still believe the theory that VEGF concentration in the tear fluid of scleroderma patients can in fact lead to key insights into how SSc affects the eyes, and are calling for additional research methods to better measure and ascertain VEGF levels.