Glaucoma — supplement adjuncts to IOP-lowering therapy
For primary open-angle glaucoma and normal-tension glaucoma, the only intervention with proven benefit on visual-field progression is intraocular pressure (IOP) reduction — drops, laser, or surgery. The supplement layer is "neuroprotection plus blood flow," largely speculative, with the most credible adjunctive evidence for Ginkgo biloba and citicoline in normal-tension glaucoma specifically. None of these reduce IOP, and none replace the prescribed drops.
The supplement layer with credible evidence
Ginkgo biloba (EGb 761 extract)
120–240 mg/day of standardised extract (24% flavone glycosides, 6% terpene lactones)
Multiple small RCTs in normal-tension glaucoma have shown visual-field stabilisation or modest improvement on Ginkgo EGb 761 versus placebo over 4–8 weeks of supplementation. Mechanism is hypothesized to involve improved ocular blood flow and direct neuroprotection of retinal ganglion cells. The signal is not consistently present in high-tension primary open-angle glaucoma. Reasonable adjunct in normal-tension glaucoma patients already on optimal IOP-lowering therapy who continue to show visual field progression. Bleeding-risk caveat applies — discontinue 7–10 days before elective surgery; use cautiously with anticoagulants and antiplatelets.
Citicoline (CDP-choline)
500–1,000 mg/day oral; some trials use intramuscular at 1 g/day
Italian trial program (Parisi and colleagues, multiple trials over 20 years) supports citicoline as a neuroprotective adjunct in glaucoma, with modest improvements in pattern-electroretinogram and visual-evoked potential measures over 4–8 weeks of supplementation. Some trials have shown visual field stabilisation in advanced glaucoma on top of IOP control. The trials are mostly small, single-center, and have variable methodology, so effect size is uncertain. Reasonable adjunct in patients with progressive visual field loss despite well-controlled IOP.
Omega-3 (EPA/DHA)
1–2 g EPA+DHA/day
Observational data link low omega-3 intake to worse glaucoma outcomes. Modest RCT signal for ocular surface (dry eye) benefit in glaucoma patients on preserved drops, who frequently have ocular surface disease. Not a glaucoma-specific intervention but reasonable for the comorbid dry eye.
Magnesium
300–400 mg/day magnesium glycinate
Small trial signal for improved ocular blood flow in normal-tension glaucoma; effect on visual fields modest. Mostly worth supplementing for the broader cardiovascular and sleep indications; not a glaucoma-specific lever.
The Mediterranean and vegetable-heavy diet signal
Population studies (notably from the Rotterdam and Blue Mountains cohorts) link higher leafy-green and nitrate-rich vegetable intake to lower glaucoma incidence. A 2016 JAMA Ophthalmology analysis showed roughly 20% reduced primary open-angle glaucoma risk in the highest dietary nitrate quintile. This is suggestive rather than proof; it does support eating leafy greens. Translating to a beetroot supplement specifically for glaucoma is speculative.
What to skip
- "Eye health" multi-ingredient complexes with lutein, zeaxanthin, bilberry, eyebright for glaucoma — these have signal for AMD and macular health, not glaucoma. AREDS2-style formulations are for AMD; not appropriate to extrapolate.
- High-dose vitamin C "for IOP" — old reports of acute IOP reduction from oral and IV vitamin C are not replicated reliably and effect is transient.
- Resveratrol, NAD+ precursors marketed for "retinal protection" — interesting preclinical work; no clinical glaucoma evidence yet.
- CBD oil for IOP lowering — old reports of cannabinoid IOP reduction were transient and unreliable; not appropriate as primary or adjunctive therapy.
- Stopping prescribed eye drops to "use supplements instead" — leads to predictable vision loss.
The non-supplement layer that matters more
Drop adherence (or laser/SLT/surgery when adherence is impossible), regular ophthalmologist follow-up with visual field testing, avoidance of head-down activities in advanced disease, blood pressure management (over-treated nocturnal hypotension is implicated in normal-tension glaucoma progression), and sleep apnea treatment when present produce visual-field outcomes that supplements do not match.