What does vitamin K do to the eyes?: Uncovering its Vascular and Neuroprotective Roles

October 7, 2025 •

4 min read

While most people associate vitamin K with blood clotting, recent research suggests it has more nuanced benefits, including some surprising effects on eye health. So, what does vitamin K do to the eyes beyond its well-known systemic functions, and how can dietary intake impact ocular wellness? This article explores the emerging evidence behind this fat-soluble vitamin's role in vision and ocular health.

Quick Summary

Vitamin K, particularly K2, influences eye health by preventing vascular calcification, which supports retinal blood flow. It also shows potential neuroprotective effects for glaucoma and may improve the appearance of dark circles.

Key Points

Supports Ocular Vascular Integrity: Vitamin K's role in blood clotting helps maintain the health and integrity of the delicate blood vessels in and around the eyes.
May Reduce Dark Circles: Topical vitamin K is marketed to improve the appearance of dark circles by strengthening capillary walls and minimizing blood leakage under the skin.
Inhibits Vascular Calcification: Vitamin K2 activates MGP, a protein that prevents the calcification of soft tissues, including the microvessels of the retina.
Shows Neuroprotective Potential: Animal studies suggest that vitamin K1 may offer protection to retinal ganglion cells in conditions like glaucoma by increasing MGP expression.
Linked to Retinal Microvascular Health: Observational studies indicate that better vitamin K status may be associated with improved retinal microvascular diameter, a risk factor for age-related eye diseases.
Found in Dietary Sources: Vitamin K1 is primarily in leafy greens, while K2 comes from fermented foods and animal products, making a balanced diet key for intake.

The Indirect Role of Vitamin K in Ocular Health

Vitamin K is a fat-soluble vitamin primarily known for its role in regulating blood clotting. However, this function is critical for maintaining the vascular system that supplies the eyes with oxygen and nutrients. A robust circulatory system is essential for overall eye health, and vitamin K's ability to support blood vessel integrity contributes indirectly to optimal vision.

Supporting Ocular Vascular Health

Blood Clotting: Vitamin K is a necessary co-factor for the enzyme gamma-glutamylcarboxylase, which is vital for synthesizing several proteins involved in coagulation. This prevents excessive bleeding in case of injury, including the delicate blood vessels within the eyes.
Preventing Hemorrhages: A severe deficiency in vitamin K can lead to coagulopathy, a bleeding disorder that may manifest as subconjunctival hemorrhages (broken blood vessels in the eye).
Reducing Dark Circles: Topical application of vitamin K is commonly used in skincare to reduce the appearance of dark circles and bruising under the eyes. This is believed to work by strengthening capillary walls and aiding in the dispersal of blood that has pooled in the area, a common cause of discoloration. While more research is needed, this cosmetic application highlights its vascular benefits.

The Direct Impact of Vitamin K2 on Retinal Vessels

While vitamin K1 is primarily involved in coagulation, the menaquinone form, vitamin K2, has more pronounced extra-hepatic (outside the liver) effects. Research is beginning to highlight K2's specific benefits for eye health, particularly its role in managing calcium metabolism and inhibiting vascular calcification.

Inhibiting Calcification: Vitamin K2 activates Matrix Gla Protein (MGP), a potent inhibitor of vascular calcification. Since MGP is highly expressed in the eye, particularly in the trabecular meshwork, adequate vitamin K2 is crucial for maintaining the flexibility and function of retinal and ocular blood vessels. Stiff, calcified vessels can impede blood flow and contribute to eye disease.

Emerging Evidence on Glaucoma and Macular Degeneration

Recent studies have explored vitamin K's potential in mitigating vision loss from age-related conditions like glaucoma and macular degeneration (AMD). The research is promising but still in its early stages.

Glaucoma: A 2020 study on rats with chronic ocular hypertension demonstrated that a diet supplemented with high vitamin K1 protected against retinal ganglion cell loss. This neuroprotective effect is possibly linked to increased MGP expression, which is essential for regulating intraocular pressure. Observational studies have also noted that higher intake of leafy greens, a source of vitamin K1, is associated with a lower risk of glaucoma in humans.
Age-Related Macular Degeneration (AMD): Early studies suggest a link between vitamin K status and retinal microvascular health, a factor relevant to AMD risk. By inhibiting plaque build-up and promoting healthy blood flow in ocular capillaries, vitamin K may play a preventative role. However, more extensive human trials are needed to confirm this association.

Dietary Sources of Vitamin K

Obtaining sufficient vitamin K can be achieved through a balanced diet. The two main types, K1 and K2, are found in different food groups.

Vitamin K1 (Phylloquinone): Abundant in leafy green vegetables like kale, spinach, collard greens, and broccoli. It is also found in some vegetable oils.
Vitamin K2 (Menaquinone): Found in fermented foods such as natto (fermented soybeans) and some animal products, including pastured and grazed animal products (meat, butter, milk) and aged cheeses.

Comparing Vitamin K with Other Key Eye Nutrients


Nutrient	Primary Eye Health Role	How it Works	Key Food Sources
Vitamin K	Vascular integrity, blood clotting, calcium regulation, potential neuroprotection	Activates proteins like MGP to inhibit vascular calcification and support blood vessel walls; protective effects in glaucoma models.	Leafy greens (K1), fermented foods, aged cheese (K2)
Vitamin A	Retinal function, night vision, cornea health	A component of rhodopsin, a pigment essential for low-light vision; supports ocular surface epithelium.	Carrots, sweet potatoes, egg yolks, liver
Lutein & Zeaxanthin	Macular protection, blue light filtering	Acts as an antioxidant and filters harmful blue light to protect the macula.	Kale, spinach, corn, egg yolks
Vitamin C	Antioxidant protection, collagen support	A powerful antioxidant concentrated in the aqueous humor, protects against oxidative stress and supports collagen in eye structures.	Citrus fruits, strawberries, broccoli, peppers
Vitamin E	Cellular protection from oxidative damage	Protects cell membranes, particularly in the retina, from damage by free radicals.	Almonds, sunflower seeds, wheat germ, vegetable oils
Zinc	Vitamin A transport, melanin production	Transports vitamin A to the retina and is crucial for producing melanin, a protective pigment.	Oysters, red meat, nuts, seeds

Conclusion: The Nuanced Role of Vitamin K in Eye Health

While vitamin K does not directly impact eyesight in the same way as Vitamin A, which is essential for retinal pigments, its nuanced and supportive roles are increasingly recognized. The primary way what does vitamin K do to the eyes involves its critical function in maintaining the health of the eye's vascular system, preventing bleeding, and strengthening capillaries. Its more direct effects, particularly those of vitamin K2 in regulating vascular calcification and potentially offering neuroprotection for conditions like glaucoma, are a promising area of emerging research. Incorporating a diet rich in vitamin K1 and K2 is a proactive step towards supporting overall eye health and may contribute to preventing or slowing the progression of certain age-related eye conditions. As always, consult a healthcare professional before starting any new supplement regimen. For more information on vitamin K's biological functions, visit the NIH Office of Dietary Supplements.

Frequently Asked Questions

No, there is currently no evidence that vitamin K supplements can cure eye diseases. While research suggests potential protective benefits, particularly in glaucoma and vascular health, they are not a cure.

Topical vitamin K is often included in eye creams for dark circles, with some users reporting benefits. However, scientific evidence is limited, and its effectiveness depends on the underlying cause of the dark circles, such as bruising or vascular issues.

Vitamin K1 is mainly involved in blood clotting and is important for general vascular health, including in the eyes. Vitamin K2 is specifically noted for its role in regulating calcium and activating proteins that inhibit vascular calcification, which is significant for retinal blood vessels.

For most people, a balanced diet rich in leafy greens and some fermented or animal products provides sufficient vitamin K. Supplementation should only be considered after consulting a doctor, especially if you are taking blood-thinning medication.

Preliminary animal studies show that vitamin K1 supplementation can help protect retinal ganglion cells and may influence intraocular pressure. This is partly due to its role in activating Matrix Gla Protein (MGP), which regulates pressure within the eye.

A severe vitamin K deficiency can indirectly affect vision. It can cause a bleeding disorder (coagulopathy) that may lead to hemorrhages in the eye. Long-term sub-optimal vitamin K status is also linked to age-related vascular issues that impact eye health.

To get both forms of vitamin K, consume leafy greens like kale and spinach for K1, and fermented foods such as natto, as well as aged cheeses and grass-fed dairy, for K2.