Citicoline and Retinal Ganglion-Cell Function

One of the most frequently cited clinical investigations was published by Parisi and colleagues in Ophthalmology in 1999.

The investigators evaluated retinal and visual-pathway electrical responses in people with glaucoma.

Citicoline administration was associated with improvement in both:

⦁ PERG measurements, reflecting retinal neural function; and
⦁ VEP measurements, reflecting visual-pathway neural conduction.

The investigators concluded that citicoline appeared capable of improving retinal and visual-pathway function in the study population. (PubMed)

These findings subsequently stimulated longer-term studies.

Long-Term Electrophysiologic Research
In an eight-year follow-up investigation, Parisi reported that repeated periods of citicoline administration were associated with improvement in retinal and cortical bioelectrical responses measured by PERG and VEP.
The study proposed that citicoline might have a role as a complement to conventional pressure-lowering therapy in research involving glaucoma. (PubMed)
A later scientific review by Parisi and colleagues discussed these findings as suggestive of potential neuroprotective activity while recognizing the need for continued research. (PubMed)
These studies are particularly interesting because the observed physiological changes appear to involve neural function rather than intraocular-pressure reduction.

Citicoline Eye-Drop Research
Researchers have also investigated citicoline delivered topically.
A preliminary study by Roberti and colleagues evaluated citicoline-containing eye drops in people with glaucomatous optic neuropathy. Changes in electrophysiologic measures of retinal function were observed during treatment. (PubMed)
In 2015, Parisi and colleagues reported that topical citicoline treatment in open-angle glaucoma enhanced retinal bioelectrical responses and was associated with improved electrophysiological activity along the visual pathway. (PubMed)
The importance of these studies for nutritional science is not that topical and oral products are interchangeable—they are not—but that multiple routes of citicoline exposure have generated research signals involving retinal and visual neural function.

Three-Year Randomized Clinical Research
An especially important study was published by Rossetti and colleagues in the Journal of Glaucoma in 2020.
This randomized, placebo-controlled clinical trial examined citicoline eye drops as an adjunct in people whose glaucoma continued to worsen despite controlled intraocular pressure.
The investigators evaluated:
⦁ standard 24-2 visual fields;
⦁ central 10-2 visual fields; and
⦁ retinal nerve-fiber-layer OCT measurements.
The difference in the principal 24-2 visual-field progression endpoint did not reach statistical significance.

However, secondary analyses involving 10-2 visual-field progression and RNFL OCT progression favored the citicoline-treated group. The authors concluded that adjunctive citicoline eye drops might reduce progression in this selected population. (PubMed)

This study is scientifically encouraging, but it should not be interpreted to mean that oral citicoline—or Neuroptic™—has been proven to prevent or treat glaucoma.

Oral Citicoline Research
Oral citicoline has also been investigated.
Ottobelli and colleagues evaluated oral citicoline solution in patients showing relatively rapid visual-field deterioration.
The study reported a reduction in the apparent rate of glaucomatous visual-field progression after supplementation and suggested that citicoline deserved further investigation as an adjunctive strategy. (PubMed)
A separate study evaluating oral citicoline and OCT measurements reported short-term preservation of average retinal nerve-fiber-layer measurements compared with controls. (PubMed)
These findings remain preliminary and do not establish that oral citicoline prevents glaucoma progression.

Research Beyond Glaucoma
Non-Arteritic Anterior Ischemic Optic Neuropathy
Citicoline has also been investigated in another condition involving retinal ganglion cells and the optic nerve: non-arteritic anterior ischemic optic neuropathy, or NAION.
In a randomized pilot study, Parisi and colleagues evaluated 500 mg/day oral citicoline for six months, followed by washout.

The treated group demonstrated favorable changes in several functional and structural measures, including visual acuity, electrophysiology and visual-field parameters compared with the untreated group. (PubMed)
Because this was a relatively small pilot study, the results should be regarded as encouraging rather than definitive.

Experimental Evidence: Looking Beyond the Eye
A sophisticated experimental study published in Neurotherapeutics examined citicoline in a model of chronic elevated intraocular pressure.
Investigators evaluated the visual system using:
⦁ MRI;
⦁ measures of axonal transport;
⦁ visual behavior;
⦁ optic-nerve histology;
⦁ visual-brain connectivity; and
⦁ neuronal structural markers.

Citicoline reduced deterioration in several measures of visual-system integrity and visual performance without significantly altering intraocular pressure. (PubMed)
This research supports an important scientific principle behind Neuroptic™:
Vision is a neural process extending from the retina to the brain.
Supporting visual health therefore involves consideration of the retina–optic nerve–brain axis, not simply the optical structures of the eye.

What Does the Total Evidence Actually Show?
Citicoline has one of the more extensive research histories among nutritional compounds investigated for retinal ganglion-cell and visual-pathway function.
But scientific credibility requires presenting both positive and negative evidence.
A 2023 systematic review by Prinz and colleagues analyzed 10 clinical studies involving 424 patients with glaucoma.
When results were pooled, there was insufficient evidence to establish a statistically significant overall benefit of citicoline for major conventional endpoints including:
⦁ intraocular pressure;
⦁ 24-2 visual-field mean deviation;
⦁ retinal nerve-fiber-layer thickness; and
⦁ PERG amplitude.
The authors concluded that there was insufficient evidence to establish that citicoline slows glaucoma progression. (PLOS)
This is an important limitation—and one that Neuroptic™ believes should be communicated openly.

Neuroprotection vs. Neuroenhancement
Understanding the difference is critical.

Neuroenhancement
Neuroenhancement means improving the function of neural tissue that is still alive but may be operating inefficiently.
Repeated improvements in PERG and VEP reported in several citicoline studies are consistent with enhanced neural function or signaling. (PubMed)

Neuroprotection
True neuroprotection would mean demonstrating that a compound prevents or materially slows irreversible neuronal or axonal loss over time.
Although animal studies and selected clinical investigations provide promising signals, long-term structural neuroprotection has not yet been conclusively established in humans. The 2023 systematic review reinforces this distinction. (PubMed)
For this reason, Neuroptic™ does not characterize citicoline as a cure or treatment for glaucoma or optic neuropathy.

Why Citicoline Fits the Neuroptic™ Philosophy
Neuroptic™ is built around a broader vision-science concept:
Support the biological systems that healthy retinal and neural tissues require.

Citicoline contributes a distinctive nutritional role because its scientific literature relates to:
Neuronal membrane metabolism
Citicoline participates in phosphatidylcholine biosynthesis.

Retinal neural signaling
Clinical studies have repeatedly evaluated PERG responses following citicoline exposure.

Retina-to-brain communication
VEP studies have investigated neural conduction through the visual pathway.

Cellular resilience
Laboratory studies provide evidence supporting investigation of citicoline under conditions of metabolic and neuronal stress.

The optic nerve–brain connection
Contemporary research increasingly considers glaucoma and related optic neuropathies within the broader framework of neurodegeneration involving the entire visual system.
This makes citicoline scientifically complementary to a comprehensive nutritional strategy designed to support normal cellular metabolism, antioxidant defense and neural visual function.

The Neuroptic™ Scientific Standard
We believe confidence should come from transparent science—not exaggerated promises.
For that reason, Bionutrex distinguishes among three levels of evidence:

Established Biology
Citicoline is a naturally occurring intermediate involved in phosphatidylcholine synthesis and neuronal membrane metabolism. (PubMed)

Promising Clinical Evidence
Multiple human studies have reported changes in retinal electrophysiology, visual-pathway electrophysiology and selected structural or functional outcomes following citicoline administration. (PubMed)

Questions Still Being Studied
It has not been definitively established that citicoline prevents retinal ganglion-cell death, reliably slows glaucoma progression or prevents blindness in humans. (PLOS)
That distinction matters.
It allows Neuroptic™ to remain grounded in the emerging science of nutritional neural support without presenting a dietary supplement as a medical treatment.