Normal-tension glaucoma carries increased risk of stroke
Patients with normal-tension glaucoma (NTG) are at an increased risk of developing subsequent stroke, and this observation holds true for NTG patients presenting with different comorbidities, a study has found.
The population-based retrospective cohort study used data from the Taiwan National Health Insurance Database, including 943 patients diagnosed with NTG aged ≥20 years (mean age 53.84 years; 51.43 percent male) and 4,715 controls (mean age 54.35 years; 51.43 percent male). Age, gender and pre-existing comorbidities (hypertension, diabetes, congestive heart failure, ischaemic heart disease, atrial fibrillation and disorders of lipid metabolism) were examined.
Overall, 203 developed stroke during a 10-year follow-up, accounting for 107 in the NTG group (11.35 percent) and 96 in the comparison group (2.04 percent). On Cox regression, the risk of developing stroke was more than sixfold greater in NTG patients than in controls (adjusted hazard ratio [HR], 6.34; 95 percent CI, 4.80 to 8.38; p<0.0001). NTG was also found to be associated with significantly lower stroke-free survival rates (p<0.0001).
A subgroup analysis by different comorbidities yielded similar results, with HRs for stroke in NTG patients ranging between 4.38 and 6.88.
Glaucoma is diagnosed when the intraocular pressure (IOP) is 21 mm Hg or higher, although the eye disease can develop at any IOP level, with affected individuals having typical glaucomatous optic nerve head damage and visual field changes. It is said that NTG is more IOP-independent compared with primary open-angle glaucoma (POAG), such that IOP reduction does not exert a beneficial effect on disease progression in NTG as it does in POAG. Vascular insufficiency in the central nervous system has been implicated in the pathogenesis of NTG, with cerebrovascular diseases being more common in NTG patients than in those with high-tension glaucoma or without glaucoma. [J Ophthalmol 2003;136:820–8; Arch Ophthalmol 2002;120:1268–1279]