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William M Norkett, Kelsey Green, Ai Ren, Loyal Walker, Angelo P Tanna, Louis R Pasquale, Paul A Knepper; Thrombi to hemorrhages: The ins and outs of microvascular disease in glaucoma.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2740.
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© ARVO (1962-2015); The Authors (2016-present)
Patients with normal tension glaucoma (NTG) and primary open angle glaucoma (POAG) frequently have optic nerve hemorrhages; a hemorrhage is an important clinical marker of visual field deterioration in both types of glaucoma. Hemorrhages also occur in the nailfold capillary bed of POAG and NTG patients, suggesting that these diseases have systemic manifestations. In this study, nailfold capillaries were analyzed to classify microvascular events in NTG and POAG patients.
Microvascular events were documented by video microscopy using a JH-1004 capillaroscope at 280X magnification on the subject’s fourth and fifth finger of the non-dominant hand and categorized by two masked observers. Major outcomes were classified based on whether the microvascular events were observed in the capillary (intravascular thrombus) or outside the capillary (extravascular hemorrhage); fresh event (reddish in color) or old event (characterized by a brownish, hemosiderin color); location, pattern, patency (blood freely flowing within the capillary); and the size of vascular event. Statistical analyses were calculated using ANOVA tests and unpaired, two-tailed T-tests.
The total microvascular events observed in controls included 26 events in nine subjects from a sample size of 138 subjects, POAG patients had 178 events in 86 patients from a sample size of 176 patients, and NTG patients had 83 events in 7 patients from a sample size of 28 patients (Table 1). Fresh, intravascular thrombi compared to fresh, extravascular hemorrhages were significant (p<0.003) by ANOVA analysis and was highly significant (p<0.00005) by T-test of POAG compared to NTG.
Intravascular thrombi were common in NTG whereas extravascular hemorrhages were observed in POAG. The thrombi microvascular events in NTG may be the result of stasis secondary to vascular dysfunction whereas hemorrhages in POAG may be the result of capillary wall leakage and/or faulty repair of the capillary defect by endothelial progenitor cells, although further studies are needed to confirm this hypothesis. These microvascular events are systemic manifestations of POAG and NTG, and nailfold video microscopy may be useful adjunct test in predicting similar events in the optic nerve of patients with glaucoma. Sequential nailfold capillary microscopy may facilitate the interpretation of microvascular events in glaucomatous thrombi and hemorrhages.
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