Clinical research on the association between hypertension and elevated intraocular pressure (IOP) has been increasing. Umetsu et al. showed that even when IOP is in the normal range, patients with high IOP are independently associated with the development of new hypertension at a 10-year follow-up [1]. Hypertension Research recently prepared and published a comment on hypertension and glaucoma from the group of Umetsu et al. [2]. The authors discuss that the mechanisms involved are diverse since autonomic and hormonal factors regulate the production of fusiform fluid from the ciliary body. For example, the involvement of the renin-angiotensin system (RAS) has been suggested as a common factor in the increase in blood pressure and IOP Buonfiglio et al. recently reported a review article on the relationship between glaucoma and the RAS, and considered the involvement of oxidative stress, increased inflammation, and accelerated remodeling due to the RAS.

In a cross-sectional study of the association between blood pressure and IOP in 6783 subjects aged 40 years or older, Yasukawa et al. found that SBP and DBP levels were positively associated with IOP levels, even after adjustment for known confounders, with a multivariate adjusted odds ratio of 1.88 (95% confidence interval, 1.14–3.08) [3]. Rajasundaram et al. also showed that elevated SBP and DBP were associated with elevated IOP and that elevated blood pressure was also associated with retinal ganglion cell degeneration, but interestingly, no association between IOP and retinal ganglion cell degeneration was not found [4]; Pham et al. reported that long-term variability in blood pressure is associated with visual field progression in glaucoma patients [5].

Previously, low ocular perfusion pressure and hypotension were considered a risk for glaucoma, and it was sometimes thought that glaucoma could be treated by increasing blood pressure [6]. Interestingly, spontaneously hypertensive rats (SHR) have been reported to have lower intraocular pressure than normotensive Wistar Kyoto rats (NR) despite hypertension [7, 8]. The effects of vascular rarefaction of ciliary and choroidal capillaries and reduced aqueous humor formation due to changes in capillary endothelium, among others, have been postulated, but basic research did not confirm this glaucoma risk by hypotension [9], There is growing evidence that glaucoma is associated with hypertension, and a search on PubMed using the search formula “glaucoma and hypertension” reveals over 10,000 hits, with reports nudging up, and in 2019 Perhaps due in part to Leeman et al. reporting a review of glaucoma and hypertension in Hypertension, more than 500 papers have been reported each year since around 2020. Although there is a commonality of pressure, “pressure” is not necessarily associated with glaucoma as in normal pressure glaucoma, so it is not that hypertension causes glaucoma, but rather that there is a common factor at the top, that systemic environmental changes that trigger hypertension are likely to lead to the development of glaucoma as well, and If we assume that prevention of sensory system dysfunction, which reduces quality of life, is important for patients, and that appropriate treatment of hypertension reduces common factors upstream, leading to reduced sensory system dysfunction, then the importance of antihypertensive treatment could be pointed out (Fig. 1).

Schematic presentation of the relation between glaucoma and systemic hypertension. A growing number of reports suggest a link between hypertension and glaucoma. Patients with hypertension tend to have higher, even normal, intraocular pressure. Although the upstream blood pressure theory, which considers whether high blood pressure raises intraocular pressure or whether vascular damage associated with high blood pressure is involved in the development of glaucoma, has been considered, the involvement of the renin-angiotensin system and inflammation and oxidative stress are commonly found in both, suggesting that lifestyle and other influences may be responsible for the common upstream Therefore, it can be said that the common upstream factors that raise blood pressure and intraocular pressure are the result of independent induction of both conditions by lifestyle and other factors. Further basic research is expected to be conducted in the future

The association between ophthalmology and hypertension has long been focused on hypertensive retinopathy based on the evaluation of fundus vessels, but associations have also been reported in glaucoma, cataracts, and age-related macular degeneration. For details, please refer to my book [10]. By examining in detail, the relationship between hypertension and these previously unnoticed areas, and proving the direct or indirect effects of antihypertensive treatment, it is possible that treatments that improve quality of life will result.