Abstract
Purpose:
Vascular dysfunction and microhemorrhages are characteristic of many connective tissue diseases, e.g. scleroderma and systemic lupus erythematosus. The purpose of this study is to evaluate a systemic feature of primary open-angle glaucoma (POAG) with nailfold video capillaroscopy and hyaluronic acid (HA) profiling.
Methods:
Nailfold video capillaroscopy using a JH-1004 Capillaroscope was performed on low-tension POAG patients (n=7) and on aged-matched normal “control” subjects (n=7). Videos were taken of the subject’s third and fourth fingers on their non-dominant hand. Videos were analyzed to determine capillary morphology. Capillaries were qualified as normal (hairpin loop), tortuous, bizarre, ramified, bushy, crossed, or widened. Additionally, hemorrhages and avascular areas were recorded, and overall torquation was calculated. HA profiling of human serum was completed through glycosaminoglycan (GAG) isolation and HA extraction. GAG isolation was performed on normal and low-tension POAG patient human serum using protease degradation, RNase treatment, DNase treatment, trichloroacetic acid precipitation, and selective alcohol precipitation. HA was extracted from the isolated GAG samples using 0.4M NaCl in 0.1% cetylpyridinium chloride. The isolated HA was run on a 15% TBE gel, and stained with Stains-All. HA ladders of 25kD to 500kD were used to determine the molecular weights and densitometry was performed using Metamorph to determine the relative HA sizes.
Results:
Microhemorrhages were observed in all low-tension POAG patients and in only 1 of 7 control subjects (P<0.001). There were 35 hemorrhages in 560 capillaries resulting in a 6.3% incidence. POAG subjects had an average torquation of 1.6±0.2 while normal subjects had an average torquation of 1.7±0.6. HA concentration tended to decline in POAG serum, with a qualitative difference in low molecular weight HA species observed in POAG patients
Conclusions:
In all low-tension POAG patients, microhemorrhages were observed. The direct cause of the microhemorrhages remains undetermined, as there are many possible factors. Such factors include capillary growth regulation, breakdown of support matrix, blood flow velocity, and neurogenic dysfunction. The relative amounts and size of HA described in the HA profiling may provide insight to the capillary growth regulation. Thus, we conclude POAG has systemic features characteristic of connective tissue diseases.
Keywords: 661 proteoglycans/glycosaminoglycans •
519 extracellular matrix