Antihypertensive Medications May Have Protective Effect Against Developing Glaucoma

Larry Hand

December 09, 2016

COPENHAGEN, DENMARK — Antihypertensive medications may have a preventive effect on developing glaucoma in people 40 years old or older, according to results of a study of the Danish population[1].

"Cardiologists should be aware that hypertensive patients are at a higher risk of developing glaucoma," Dr Anna Horwitz (University of Copenhagen) told heartwire from Medscape. "Furthermore, they should be aware that there may be a preventive effect of antihypertensive medication on glaucoma and that some types of medication seem to have a better preventive effect than others. In particular, antiadrenergic drugs seem to have the greatest protective effect."

But Dr Anthony Khawaja (Moorfields Eye Hospital, London, UK), an author of a 2014 article on systemic medication and intraocular pressure[2] who was not involved in this study, told heartwire , "The results of this study need to be interpreted with caution. There are significant limitations in the study design, which are not uncommon with real-world evidence. Glaucoma is a heterogeneous group of conditions that share similar clinical features but have different causes."

Horwitz and colleagues analyzed data on the complete Danish population aged 40 to 95 years from 1996 to 2012, covering more than 2.6 million people. They used the National Danish Registry of Medicinal Products Statistics to identify claimed prescriptions for glaucoma and antihypertensive medications.

They found that although hypertension is positively associated with development of glaucoma, antihypertensive medication may delay development of glaucoma.

During the study period 739,494 patients received antihypertensive medications, while 115,617 patients between 40 and 95 years old received were also glaucoma patients.

Among the patients receiving antihypertensive medications, 5.8% started treatment with glaucoma medication, compared with 1.3% of patients not receiving antihypertensive medication. Also, 32.1% of glaucoma patients were prescribed antihypertensive medication during the period.

The rate of glaucoma among individuals treated with antihypertensives turned out to be 0.81 cases per 100 person-years, compared with the rate of 0.19 cases per 100 person-years among individuals not treated with antihypertensives.

However, they point out that the risks of developing either disease increase with age and that antihypertensive treatment reduces the risk of developing glaucoma by about 43%.

The results were published online December 5, 2016 in Hypertension.

"If the findings are taken at face value, they imply that the beneficial effects of most antihypertensive medications on glaucoma development should be taken into account when considering the trade-off between the costs and benefits of treatment," Horwitz told heartwire. "In particular, if the findings are verified in future research, they may imply that it could be optimal to use antihypertensive medication at a lower blood-pressure threshold and increasingly so for individuals at a higher risk for glaucoma, due to the beneficial effects on glaucoma."

She continued, "Based on the higher risk of glaucoma that we observe in hypertensive patients (even when controlling for age and gender), hypertensive patients should possibly be referred to ophthalmologists at a higher rate than currently, especially in relation to patients with a greater disposition for glaucoma—for example, patients with a strong family history of glaucoma."

The study results "may imply that cardiologists and ophthalmologists should be jointly involved in the prevention or treatment of certain eye diseases," she said.

"We would like to emphasize that our analysis not only establishes a preventive effect of antihypertensive medication on the risk of developing glaucoma but that it also shows that individuals treated with a higher number of different antihypertensive drugs obtain a larger degree of protection, further strengthening the validity of our findings," she said.

"In addition, we find that all types of antihypertensive medications, except vasodilators (such as hydralazine) . . . are estimated to have a protective effect. This concordance between qualitative conclusions further strengthens our analysis by providing a consistent picture of the preventive effect of antihypertensive medication on glaucoma," she said.

Khawaya noted, however, "A common cause of glaucoma is a neovascular process caused by diabetic retinopathy or a retinal vein occlusion. It is logical that managing hypertension would reduce the risk of diabetic retinopathy or retinal vein occlusion and therefore reduce this type of glaucoma. But what about for primary open-angle glaucoma, the commonest chronic form of glaucoma? Actually, the opposite may be true.

"At present," he said, "I do not believe there is sufficient evidence to support the use of antihypertensives in glaucoma, other than preventing glaucoma related to the known sequelae of diabetes or retinal vein occlusion. Use of antihypertensives should not be discouraged given their proven benefit on survival, but caution is recommended to avoid overtreating patients, especially if they have established primary open-angle glaucoma."

Fight for Sight, Denmark, and the Nordea Foundation supported this research. The authors reported no relevant financial relationships.

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