Visual acuity measures the eye's ability to distinguish fine details—expressed in tenths or on the Snellen chart. A visual acuity of 10/10 means that the subject can distinguish the details of a standardized eye chart from 5 meters away, which corresponds to the reference value for an eye without refractive error. This measurement primarily assesses the function of the cones in the fovea (center of the retina) and the sharpness of the projected image. It is distinct from peripheral vision, contrast sensitivity, and color vision—which can deteriorate independently of central visual acuity.
Folic acid (B9, 400–800 µg/day) regulates homocysteine metabolism—and elevated plasma homocysteine levels are an independent risk factor for optic neuropathy and macular degeneration, according to a meta-analysis by Huang et al. (2018). Vitamin B3 (niacinamide, 300–1,000 mg/day) is a precursor of NAD+ in retinal ganglion cells—and its protective role against cell death in experimental glaucoma models has been documented (Williams et al., 2017).
Foveal cones have one of the highest mitochondrial concentrations in the body.Ubiquinol (the reduced form of CoQ10, 100–200 mg/day) optimizes their mitochondrial respiratory chain and reduces light-induced oxidative stress. Its concentration in the retina declines with age—a mechanism that contributes to the gradual decline in visual resolution and color discrimination after age 50.
Horsetail (Equisetum arvense, standardized extract) is the plant source with the highest concentration of bioavailable organic silica. Silica plays a role in the organization of collagen fibers in the lens capsule and in the Bruch’s membranes of the retina. At 30–50 mg/day of absorbable silica, it improves the elasticity and resistance to oxidative stress of the ocular membranes—providing relevant structural support for the prevention of lens aging, in addition to conventional antioxidants.
The choice depends on the primary symptom. Refractive errors (myopia, hyperopia): appropriate optical correction remains irreplaceable—blueberry, lutein, and ubiquinol improve comfort and resistance to eye strain without correcting the refractive error. Presbyopia after age 45: silica, vitamin C, and oral collagen to slow lens aging. Reduced contrast sensitivity or impaired visual field: folic acid, vitamin B3, and carnitine as neuroprotective agents for ganglion cells. Fluctuating visual acuity in the late afternoon: check your prescription before taking any supplements. For a comprehensive approach to eye health, these supplements are part of an overall eye health prevention strategy.
Certain warning signs require an immediate ophthalmology consultation. A sudden decrease in visual acuity (even if unilateral and mild), new floaters, or a gray haze in the visual field (possible retinal detachment), distortion of straight lines (the Amsler grid sign, characteristic of exudative AMD), a difference of one-tenth in visual acuity between the two eyes, or any unexplained progressive decline in night vision. Tired eyes with fluctuating visual acuity may mask uncorrected ametropia—a comprehensive refraction evaluation is essential before attributing the decline in visual acuity to a nutritional deficiency.
