In the news: Blood Pressure, Medications, & Ocular Health

Hypertension, Medications & Ocular Health
 
Four recently published papers report associations between blood pressure – or commonly used drugs – and intraocular pressure (IOP), ocular disease, or ocular function. In the context of these studies, the DASH diet (Dietary Approach to Stop Hypertension) merits renewed attention. View instructions for implementing this AHA and NHLBI recommended diet.
 
Blood Pressure Associated with IOP, Glaucoma

The 1st investigation (1), a systematic review and meta-analysis that included 60 observational studies, found a consistent association between hypertension and increased IOP.

A significant link between elevated blood pressure and primary open angle glaucoma (POAG) was also observed when patients with hypertension were compared to those without it. The authors point out that additional studies are needed to clarify the role of blood pressure in POAG development.
 
Link Between Systemic Medications and IOP

Lower IOP was associated with oral use of β-blockers or nitrates (vasodilators) in the 2nd investigation, a population-based study (2) of 7000+ older British men and women. Use of these drugs was independently linked to lower IOP: roughly 1 mmHg and 0.6 mmHg lower for β-blockers and nitrates, respectively.

The findings of this study may have implications for managing glaucoma patients who are taking nitrates, to treat or prevent angina, or those using β-blockers for cardiovascular disorders including hypertension.

Beta-blockers, Nitrates and AMD Risk

While β-blockers and nitrates could potentially have salutary effects on IOP, the results of the 3rd study (3) raise questions about their impact in AMD. The researchers report that in the long-term Beaver Dam Eye Study, use of any vasodilator, particularly oral nitroglycerin, was associated with a 72% greater risk of developing early AMD. Patients using oral β-blockers faced a 71% increased risk of neovascular AMD. As significant as these results may appear to be, these findings need to be replicated before changing patients’ medication regimens.

Blood Pressure & Acquired Impaired Color Vision

Is blood pressure related to acquired color vision impairment (ACVI) in middle-aged men? To shed light on this question, authors of the well designed and conducted Japanese Okubo Color Study (4) compared the highest vs. the lowest blood pressure categories in men diagnosed with ACVI (using 15 hue and 100 hue tests).

The study excluded those with congenital color vision defects, previous cerebrovascular or ocular diseases, and the use of certain medications that can affect vision, and the analyses adjusted for these and other risk factors. The authors report that hypertension significantly raised the odds of having ACVI in both “15 hue and 100 hue” tested patients.

The positive correlation of high blood pressure with the prevalence of ACVI suggests that hypertension negatively impacts vision-associated neuronal function. Deterioration of the ability to discriminate between colors has long been recognized as one of the earliest indicators of neurological degeneration, and may be related to cognitive impairment and Alzheimer’s disease later in life. The authors of this cross-sectional study call for large prospective studies to confirm their results.

References

1. Zhao D, et al. The association of blood pressure and primary open-angle glaucoma: A meta-analysis. Am J Ophthalmol. May, 2014 [Epub ahead of print].
2. Khawaja AP, et al. Systemic medication and intraocular pressure in a British population: The EPIC-Norfolk Eye Study. Ophthalmol. Apr, 2014 [Epub ahead of print].
3. Klein R, et al. Vasodilators, blood pressure-lowering medications, and age-related macular degeneration: The Beaver Dam Eye Study. Ophthalmol. Apr, 2014 [Epub ahead of print].
4. Shoji T, et al. Are middle-age blood pressure levels related to color vision impairment? The Okubo Color Study. Am J Hypertens. June, 2014 [Epub ahead of print].