Does a Positive Family History of Glaucoma Foretell Severity?
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PURPOSE/RELEVANCE: There is a threefold increase in the risk of primary open-angle glaucoma (POAG) in individuals with positive family history. We wished to see if the family history also led to a more severe form of the disease. METHODS: In an IRB-approved retrospective chart study at a university-affiliated medical center, data was collected from 224 patients diagnosed with glaucoma. Positive family history was defined by first, second, or third degree relatives affected (FHx-pos). Patients with negative family history were referred to as controls. Patients with unknown family history were excluded. Age, gender, race, BMI, cup/disk ratio (C/D), visual field defects, intraocular pressure (IOP), central corneal thickness (CCT), and current glaucoma medications were recorded. FHx-pos and control groups were compared using Fisher's Exact and Wilcoxon Rank sum tests for categorical and continuous variables, respectively. RESULTS: Among patients with glaucoma, there were 82, 120, and 22 patients with positive, negative, and unknown family history, respectively. The FHx-pos group was 47.6% white, 39% black, and 13.4% Hispanic, while the control group was 40.8% white, 40.8% black, and 18.4% Hispanic; no clinically significant differences were noted. Both groups were similar in age (63.3±14.8 vs. 64.9±11.8 years, p=0.5) and CCT (539 vs. 540 μm, p=0.8). The FHx-pos group was predominantly female (70.7% vs. 45%, p<0.001), had elevated IOPs (16.9±4.0 vs. 15.7±4.2 mm Hg, p=0.040), and were prescribed more glaucoma medications (98.9 vs. 92.5%, p=0.05). The mean C/D for both groups was approximately 0.73 (p=0.86) with the FHx-pos group having slightly more optic cupping (29.6 vs. 26.1% of patients, defined as C/D > 0.9; p=0.6). DISCUSSION: The results suggest that glaucoma patients with affected relatives tend to be female. Sex-specific genetic factors or expression may contribute to disease progression, but a full mechanism has yet to be completely delineated. The FHx-pos group also had higher IOP, required more medications, and experienced slightly more optic nerve cupping, all of which indicate a more severe form of the disease. CONCLUSION: The results of this study corroborate the importance of taking a family history of glaucoma. This is especially important for females, for whom aggressive treatment may be necessary. The gender finding merits further study into the possible heritability of predisposing factors in the pathogenesis of POAG in female populations. REFERENCES: Fingert JH. Primary open-angle glaucoma genes. Eye. 2011; 25, 587-595