Calcium Channel Blockers Are Safe in Open-Angle Glaucoma
Calcium channel blockers (CCBs) are safe to use in patients with open-angle glaucoma and carry no contraindications for this condition. In fact, emerging evidence suggests they may provide neuroprotective benefits, particularly in normal-tension glaucoma.
Guideline-Based Safety Profile
The British Hypertension Society guidelines explicitly list compelling and possible indications and contraindications for all major antihypertensive drug classes, and glaucoma does not appear as a contraindication or even a caution for calcium channel blockers 1. This stands in stark contrast to beta-blockers, which list multiple contraindications, or ACE inhibitors, which require caution in specific conditions 1.
The guidelines identify CCBs as particularly useful for:
- Elderly patients with isolated systolic hypertension 1
- Patients with angina 1
- No compelling contraindications are listed for dihydropyridine CCBs 1
Distinguishing Open-Angle from Angle-Closure Glaucoma
A critical pitfall is confusing open-angle glaucoma with angle-closure glaucoma. Anticholinergic medications are contraindicated in angle-closure glaucoma due to pupillary dilation that can precipitate acute angle closure 2. However, CCBs have no anticholinergic properties and pose no risk of precipitating angle closure 2.
Evidence for Potential Neuroprotective Benefits
Beyond safety, CCBs may actually benefit certain glaucoma patients:
Normal-Tension Glaucoma
- A 3-year randomized, placebo-controlled trial of nilvadipine (a CCB) in open-angle glaucoma patients with IOP ≤16 mmHg showed significantly less visual field progression compared to placebo (-0.01 vs. -0.27 dB/year, P=0.040) 3
- The same study demonstrated sustained 30-40% increases in optic disc rim and choroidal circulation throughout the 3-year period (P=0.003 and P=0.007 respectively) 3
- A retrospective study found that among low-tension glaucoma patients, only 11% taking CCBs showed visual field progression versus 56% of controls, with no optic nerve progression in the CCB group versus 44% in controls 4
Primary Open-Angle Glaucoma
- A large retrospective analysis found no detrimental effect of oral CCBs on visual fields, optic discs, or IOP control in open-angle glaucoma patients 5
- Topical CCBs in primate studies reduced IOP by 6-19% depending on the specific agent, with additive or synergistic effects when combined with standard glaucoma medications 6
Important Caveat: Amlodipine-Specific Concern
One notable exception requires attention: A 2024 study using MedWatch and UK Biobank data found that amlodipine specifically increased POAG risk by 16.1% (P=0.032), though this did not correlate with increased IOP 7. The mechanism appears related to genetic variants in CDKN2B-AS1 and SIX6 genes rather than IOP elevation 7.
Clinical recommendation: For hypertensive patients with glaucoma or at high risk for glaucoma, consider alternative CCBs (such as nifedipine or diltiazem) or switch to diuretics or beta-blockers, which are not associated with POAG risk 7.
Practical Implementation
When prescribing CCBs for hypertensive patients with open-angle glaucoma:
- Continue standard glaucoma monitoring with regular IOP checks, visual field testing, and optic nerve assessment 1
- Target IOP reduction of approximately 20% from baseline remains the primary goal regardless of systemic antihypertensive choice 8, 9
- Consider nilvadipine or other non-amlodipine CCBs if neuroprotection is a consideration, particularly in normal-tension glaucoma 3, 4
- Avoid amlodipine in patients with established glaucoma or strong family history, opting for alternative antihypertensives 7
The rate-limiting CCBs (verapamil, diltiazem) should be used with caution when combined with beta-blockade due to potential heart block, but this is a cardiac rather than ocular concern 1.