By Gail F. Schwartz, MD
The authors of this study published in the October issue of the Archives of Ophthalmology examined nailfold capillary changes in patients with glaucoma, and found a strong association between the presence of optic disc hemorrhage and nail bed hemorrhage These associations were stronger in patients with normal-tension glaucoma (NTG) than primary open-angle glaucoma (POAG), although POAG patients with disc hemorrhage also had considerable abnormalities in peripheral microcirculation.
This article is worth reading due to its originality for the subspecialty of glaucoma. The technique of nailfold capillaroscopy, quite outside our normal realm of diagnostic testing, could become noteworthy. Although vascular hypotheses for glaucoma have been around for decades, primarily for low-tension glaucoma, ocular blood flow studies have been inconclusive.
The study included 108 glaucoma patients, of whom 86 had NTG and 22 had POAG, and 38 control patients. Patients underwent a complete ophthalmic examination and physical examination. All subjects underwent nailfold capillaroscopy, with the results analyzed by a single masked observer.
Nailfold capillaroscopy results among glaucoma patients indicated dilated vessels in 55.6 percent, loss of capillaries in 35.2 percent and nail bed hemorrhages in 19.4 percent. Disc hemorrhage was significantly associated with avascular area (odds ratio, 11.13; P < 0.001) and nail bed hemorrhage (81.59; P < 0.001). By multivariate logistic regression analysis, avascular area and nail bed hemorrhage continued to be independently associated with the presence of disc hemorrhages in glaucoma patients. No significant differences of association were found between NTG and POAG patients.
These results are consistent with reports that peripheral microcirculation in glaucoma patients is abnormal. The authors found this more likely to be true for glaucoma patients with optic disc hemorrhage, which presented as avascular areas and nail bed hemorrhages on nailfold capillaroscopy. This suggests that glaucoma patients with optic disc hemorrhage have considerable peripheral vascular insufficiency and adds weight to the hypothesis that the pathogenesis of disc hemorrhage could be of vascular origin.
The stronger association in NTG than POAG patients provides more evidence of abnormal microcirculation in NTG patients. However, disc hemorrhage was associated with nailfold hemorrhage with an OR of 17.55 (95% CI, 8.53-69.54; P < 0.001) in POAG patients, which suggests that abnormalities in the peripheral microcirculation coexist with disc hemorrhage in POAG patients. The authors say this could be a feature of optic disc hemorrhage itself rather than NTG. They say that abnormalities in peripheral microcirculation and optic disc hemorrhages are both signs of a vascular entity in glaucoma that is independent of the level of IOP.
The authors conclude that applying nailfold capillaroscopy in glaucoma patients could help identify patients at greater risk of optic disc hemorrhage. They add that it may be possible to use techniques like nailfold capillaroscopy to distinguish among glaucoma patients with and without vascular abnormalities in the future, thereby opening up new diagnostic and therapeutic options.