The following article, originally published in the highly respected German medical journal Deutsches Ärzteblatt, provides an in-depth review of the evidence on the role of vitamins, carotenoids, trace elements, and other micronutrients in supporting ocular function, protecting retinal tissue, and enhancing visual performance.
Deutsches Ärzteblatt is the official publication of the German Medical Association (Bundesärztekammer) and the National Association of Statutory Health Insurance Physicians. It reaches over 400,000 physicians across Germany and is read weekly in both print and digital formats, making it one of the most widely circulated medical journals in Europe. With peer-reviewed scientific content, clinical updates, and health policy analyses, it plays a central role in medical education and practice within the German-speaking medical community.
Much of the research featured in this article was presented at the international BON Conference (Brain and Ocular Nutrition) – a leading scientific event that brings together ophthalmologists, neuroscientists, nutrition researchers, and clinicians from around the world to explore the interplay between diet, brain health, and vision. The conference, held regularly since 2010, is a cornerstone in the field of ocular nutrition and continues to shape how nutritional approaches are integrated into eye care.
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Nutritional counselling is still generally considered primarily in terms of weight reduction or the modulation of metabolic parameters. Far less well known is the fact that one can deliberately support the long-term functional capacity of the eye through targeted nutrition.
Text | Dr Ronald Gerste, MD
The long-standing director of the University Eye Clinic in Basel and glaucoma expert, Professor Josef Flammer, MD, was a pioneer in the late 1980s when he included dietary recommendations aimed at lowering intraocular pressure, the main risk factor for glaucoma. These recommendations included green tea and broccoli, very dark chocolate and – an unusually bold suggestion in medical practice – even an occasional glass of red wine.
In an optic neuropathy such as glaucoma, in which oxidative stress plays a crucial role in the apoptosis of ganglion cells, the intake of free radical scavengers such as carotenoids, vitamins and flavonoids undoubtedly makes sense – something Flammer recognised earlier than many of his colleagues.
Normal-tension glaucoma in particular is often part of a generalised vascular dysregulation syndrome, which may include cold extremities, sleep disturbances, migraine and tinnitus. It occurs particularly frequently in younger, active women – and today bears the name Flammer syndrome.
How far knowledge has advanced in recent decades regarding the interaction between nutritional components and the preservation – or even improvement – of visual function is evident not only in the now immense range of nutritional supplements specifically designed to support vision. The high level of scientific interest is also reflected in the international response to the conference “Brain and Ocular Nutrition” (BON), held for the seventh time in 2025, this time in Beverly, near Boston (1).
Unsurprisingly, particular hope is placed in the protective effects of an antioxidant-rich diet and supplementation, especially for ocular diseases that are otherwise difficult to treat.
In geographic atrophy (GA), the primary concern is protecting the fovea. GA represents one of the two late forms of age-related macular degeneration (AMD). While anti-VEGF agents are injected into the vitreous cavity in the neovascular (“wet”) form – a therapy that is both logistically and financially demanding, with mixed long-term results – pharmacological approaches to GA have been largely disappointing. This shortcoming was already apparent in the large AREDS trial (Age-Related Eye Disease Study) – the mother of all studies on nutritional therapy in ophthalmology (2, 3).
The form of late-stage macular degeneration examined here, referred to as “dry AMD”, is characterised by geographic atrophy of the photoreceptors in the macula. The term derives from the fact that the sharply demarcated zones of cell loss can resemble desert regions on a map.
The original AREDS formula – referred to as AREDS 1 to distinguish it from its successor – contained 500 mg vitamin C, 400 IU vitamin E, 15 mg beta-carotene, 80 mg zinc and 2 mg copper. As Dr Tiarnan Keenan from the National Eye Institute in Bethesda, Maryland, recalled, this supplementation achieved an odds ratio (OR) of 0.62 for neovascular AMD in over 3,600 participants – corresponding to a 38% reduction in the progression to “wet” AMD. However, no significant effect was observed with regard to the progression from early AMD to geographic atrophy.
AREDS 2 yielded somewhat different results (4). This follow-up study, which included over 4,200 participants, tested modifications to the original formula: lutein and zeaxanthin were added, as were the omega-3 fatty acids DHA and EPA. Beta-carotene was omitted, as it had been associated with increased cancer incidence in smokers. In AREDS 2, a protective effect was demonstrated particularly for zeaxanthin and lutein.
As methodology improved and understanding of the disease process in GA became more complex, the interpretation within the “reading centres” evolved, Keenan explained. Instead of primarily assessing the progression of GA based on the size of the affected area, researchers began to focus on the distance – or rather, the proximity – of the lesion to the centre of the macula.
According to the speaker, in most cases of GA the central area remains unaffected for an extended period, giving the atrophic zone the appearance of a doughnut. A parameter of enormous importance for central visual acuity was shown to be modifiable: progression towards the foveal centre was an average of 80.1 μm per year in study participants supplemented with lutein and zeaxanthin, compared with 114.4 μm per year in patients without such supplementation (5).
Keenan pointed out that the central fovea accounts for only around 3% of the entire macula, and an effect at this crucial location for visual acuity would not be adequately captured by assessing the entire macular area. What can be hoped for – and often achieved – in the treatment of GA is foveal sparing, the preservation of the fovea.
Targeted nutritional supplementation may not only be relevant for older individuals. Although patients with advanced AMD are typically in their eighth decade of life or older, the macular pigment – composed primarily of lutein and zeaxanthin – may also have a beneficial effect on foveal maturation and visual development, explained Professor Paul S. Bernstein, MD, from the Moran Eye Center at the University of Utah in Salt Lake City.
Macular carotenoids may, among other effects, modulate the risk of retinopathy of prematurity through their antioxidative properties. Bernstein’s research group has measured macular pigment levels in infants using blue light reflectance imaging. He observed, among other findings, that maternal carotenoid levels influence the macular pigment of newborns.
This led to the initiation of the L-ZIP study (Lutein and Zeaxanthin in Pregnancy), which aimed to investigate the effects of supplementing these two substances on maternal and infant health (6).
An increase in the concentration of both substances in the serum, the skin, and the macula was demonstrated – in both the mothers and their infants. According to Bernstein, imaging of the infants’ fundus using optical coherence tomography (OCT) provided indications that their maculae exhibited a higher degree of maturity as a result of the maternal supplementation, particularly in the area of the ellipsoid zone (EZ).
Retinopathy of prematurity (ROP), the leading cause of blindness in children with a birth weight below 1,250 grams and a gestational age under 30 weeks, is exacerbated by oxidative stress. Preterm infants exhibit carotenoid deficiency – suggesting a potential new therapeutic approach, after lutein and zeaxanthin were recently shown to have a positive effect in an ROP mouse model.
Bernstein proposed an international L-ZIP2 study, in which mothers at high risk of preterm birth, or with a history of preterm delivery, would receive prophylactic supplementation – for example, 10 mg of lutein and 2 mg of zeaxanthin per day.
Another group of young individuals also appears to benefit from the intake of these carotenoids – young people who in the USA are almost regarded as the epitome of health and fitness: athletes at American colleges and universities. Optometrist Dr Fraser Horn, who looks after athletes at Pacific University near Portland, Oregon, found that most of them had good visual function – almost as expected (7).
However, just over half of them required refractive support in the form of spectacles or contact lenses to achieve full visual acuity. In view of what ophthalmologists currently describe as a “pandemic of myopia”, this is not excessively high: in universities in Southeast Asia, the proportion of short-sighted individuals often exceeds 90%.
Among the more than 300 athletes examined, those with the best visual acuity (with correction) – an above-average level of 20/15 according to the Snellen chart – were golfers, baseball players and cross-country runners.
These are all sports that rely on focus over longer distances. Swimmers and wrestlers, by contrast, had slightly less excellent visual acuity, just under 20/20 – which, according to Horn, is not problematic, as these sports primarily rely on near-distance vision.
An assessment of the carotenoid content of the skin reflects the quality of the diet, which, according to the speaker’s humorous remark, at many US universities largely consists of pizza and potato chips. Indeed, measurements using the LifeMeter – a device that non-invasively assesses carotenoid levels in the fingertips within minutes – indicated that the majority of college athletes did not intentionally follow an antioxidant-rich diet.
LifeMeter produces a score which, according to users, correlates with carotenoid levels and visual (as well as cognitive) performance. A score of 0 to 200 indicates a deficiency and is frequently associated with difficulties seeing at night, as well as an increased tendency to sunburn. A score between 200 and 400 is considered suboptimal, 400 to 600 satisfactory, and between 600 and 800 is associated with good contrast sensitivity at night, even in the presence of glare. Such high carotenoid levels are also believed to enhance memory performance and reduce “brain fog”, a term which, even when translated as “cerebral fog”, does not clearly define the phenomenon, and likely refers to a subjectively perceived cognitive dullness.
Among Horn’s student athletes, the average score was 302 – not a particularly strong value. However, the (few) cross-country runners achieved an average score of 473.
Some individual cases presented anecdotally appeared to support the connection between a healthy diet – often shaped by family background – and performance. One baseball player achieved a score of 700. When asked, he explained that he was from Hawaii, his parents ran a smoothie shop, and his mother was a dietician.
At the other end of the scale was a fellow student and basketball player with a score of 265. According to Horn’s report, his coach described him as the worst athlete at the entire college, with no motivation to improve.
It makes sense, the speaker concluded, for general practitioners, paediatricians, sports physicians, educators and coaches to encourage young people not only to eat healthily, but also to consider supplementing with high-quality nutritional products – and not necessarily those from a supermarket shelf – in order to provide essential substances such as lutein and zeaxanthin.
Vitreous floaters are often extremely bothersome and can significantly impair visual quality of life for some affected individuals. Dr Thomas Kaercher, MD, an ophthalmologist in private practice in Heidelberg, presented an alternative to treatment with YAG laser or vitrectomy. Traditionally, in cases of mouches volantes, the approach has been to adopt a watchful waiting strategy or even to forgo treatment entirely, in the expectation that the floaters will resolve on their own. However, this often fails to help patients. Kaercher described YAG laser vitreolysis and vitrectomy as highly invasive treatment approaches.
Kaercher contrasted these methods with the administration of a targeted and commercially available micronutrient complex containing 125 mg L-lysine, 100 mg citrus fruit extract, 40 mg vitamin C, 26.3 mg grape seed extract and 5 mg zinc. This complex represents a clinically tested, non-invasive option for the treatment of floaters.
Its efficacy has been demonstrated in five clinical studies, including the double-masked, randomised, controlled trial FLIES (Floater Intervention Study) (8). This study showed improvements in subjective vision-related quality of life, as well as reductions in objectively measured areas of vitreous opacity and contrast sensitivity loss.
Kaercher conducted a survey among 96 ophthalmologists in Germany and Austria who recommend this approach to their patients with floaters (9). The average length of experience with the micronutrient complex was 4.18 years. Most respondents (75%) had at least two years of experience, while 10% had been familiar with the treatment for more than nine years.
A total of 58.9% of respondents rated the nutritional supplement as helpful, while 24.2% considered it extremely helpful. According to Kaercher, patients affected by vitreous opacities are often better informed about this intervention than some specialists, as the level of distress frequently leads to intensive internet research.
Conferences such as BON aim, not least, to raise greater awareness among physicians of the potential of micronutrients for ocular health.
Carotenoids are not the only substances with ocular benefits. Coenzyme Q10 (ubiquinone) is a lipophilic molecule naturally present in the mitochondria of eukaryotic cells, structurally related to vitamins K and E. As Dr Cemre Altas, MD, an ophthalmologist at the University Eye Clinic in Rostock, explained, current research suggests considerable therapeutic potential for CoQ10 in ophthalmology.
Coenzyme Q10 (CoQ10) plays a role in mitochondrial energy production, antioxidant protection, and the regulation of apoptosis. CoQ10 levels decrease with age, reflecting an increased vulnerability of the mitochondria.
In a study involving 40 patients, the topical application of CoQ10 and vitamin E was investigated for its effect on corneal nerve regeneration following uncomplicated cataract surgery (10). The fellow eyes served as controls and received saline solution.
Ocular surface tests such as BUT (tear film break-up time), Schirmer test and aesthesiometry were performed, along with in vivo confocal microscopy of the subbasal nerve plexus at baseline, day 14, and after 3, 6, and 9 months.
The CoQ10 group showed significantly faster nerve regeneration, for example, an increase of +2.5 nerve fibres per examined field in month three, compared with an average of +1.0 fibres per field in the control group. Improved tear film stability was also documented throughout the entire study period.
Another cohort of 40 patients with dry eye disease (DED) underwent treatment in a separate three-month study, receiving either standard topical hyaluronic acid or cross-linked hyaluronic acid (XLHA) combined with CoQ10 (each applied four times daily) (11).
In the latter group, Meibomian gland function improved, while corneal staining decreased. The superior efficacy of the XLHA and CoQ10 combination appears to derive from its prolonged residence time on the ocular surface and the antioxidant effects of CoQ10.
A neuroprotective effect from the combination of CoQ10 and vitamin E was demonstrated in an animal model, where the apoptosis rate of ganglion cells was reduced by approximately 50% under this nutritional intervention.
According to Dr Altas, these study results provide a solid foundation for further investigations into CoQ10 as a therapeutic agent for glaucoma and ocular surface diseases (10, 11).
BON Conference: https://www.bonconference.org/
2
Souied EH, Aslam T, Garcia-Layana A, et al.: Omega-3 Fatty Acids and Age-Related Macular Degeneration. Ophthalmic Res 2015; 55 (2): 62–9. CrossRef MEDLINE
3
Agrón E, Vance E, Domalpally A, et al.: Relationships Between Diet and Geographic Atrophy Progression in the Age-Related Eye Diseases Studies 1 and 2. Nutrients 2025; 17 (5): 771. CrossRef MEDLINE PubMed Central
4
Chew EY, Clemons TE, Agrón E et al.: AREDS2 Research Group: Long-term Outcomes of Adding Lutein/Zeaxanthin and ω-3 Fatty Acids to the AREDS Supplements on Age-Related Macular Degeneration Progression: AREDS2 Report 28. JAMA Ophthalmol 2022; 140: 692–8.
5
Keenan TDL, Agrón E, Keane PA et al.: Age-Related Eye Disease Study Research Group; Age-Related Eye Disease Study 2 Research Group: Oral Antioxidant and Lutein/Zeaxanthin Supplements Slow Geographic Atrophy Progression to the Fovea in Age-Related Macular Degeneration. Ophthalmology 2025; 132: 14–29. CrossRef MEDLINE
6
Addo EK, Gorusupudi A, Allman S, et al.: The Lutein and Zeaxanthin in Pregnancy (L-ZIP) study-carotenoid supplementation during pregnancy: ocular and systemic effects-study protocol for a randomized contro MEDLINE led trial. Trials 2021; 22 (1): 300. CrossRef MEDLINE PubMed Central
7
Shekar SU, Erickson GB, Horn F, et al.: Efficacy of a Digital Sports Vision Training Program for Improving Visual Abilities in Collegiate Baseball and Softball Athletes. Optom Vis Sci 2021; 98 (7): 815–25. CrossRef MEDLINE
8
Ankamah E, Green-Gomez M, Roche W et al.: Dietary Intervention With a Targeted Micronutrient Formulation Reduces the Visual Discomfort Associated With Vitreous Degeneration. Transl Vis Sci Technol 2021; 10 (12): 19. CrossRef MEDLINE PubMed Central
9
Wirth F, Roche W, Osęka M, et al.: Nutritional Intervention in Floaters: Evaluating the Efficacy of VitroCap®N from the Perspective of Eye Care Professionals. BON Conference 2025, Abstract 032. J Alzheimers Dis 2025; 106 (1_suppl): S19.
10
Fogagnolo P, Sacchi M, Ceresara G, et al.: The effects of topical coenzyme Q10 and vitamin E D-alpha-tocopheryl polyethylene glycol 1000 succinate after cataract surgery: a clinical and in vivo confocal study. Ophthalmologica. 2013; 229 (1): 26–31. CrossRef MEDLINE
11
Postorino EI, Rania L, Aragona E, et al.: Efficacy of eyedrops containing cross-linked hyaluronic acid and coenzyme Q10 in treating patients with mild to moderate dry eye. Eur J Ophthalmol 2018; 28 (1): 25–31. CrossRef
