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Vitamin K is important for blood clotting and may indirectly affect the vascular health of the eye. Vitamin K is also involved in the synthesis of myelin, the protective sheath around nerve fibers. Proper myelination is crucial for the health of the optic nerve []. The Vitamin B Complex, comprising eight water-soluble vitamins, plays a critical role in safeguarding overall eye health and reducing the risk of conditions like cataracts and glaucoma [,].

These vitamins act as coenzymes and are particularly relevant for ocular well-being. For example, Vitamin B1 thiamine possesses antioxidative properties and supports nerve function [], they play a critical role as coenzymes for various enzymatic reactions.

Vitamins B1, B6, and B12, called neurotropic vitamins, are essential to maintain the health of the nervous system, including the optic nerve [].

Vitamins B1, B2, B6, and B12 have functions that include antioxidative properties, immune system regulation, and the promotion of nerve survival and regeneration [].

These vitamins mainly function as coenzymes and are instrumental in maintaining ocular surface equilibrium and preventing DED []. Several micronutrients in the Vitamin B group are associated with DED, particularly DED related to neuropathic ocular pain NOP [].

Studies have shown promising results in improving tear secretion and DED symptoms through the supplementation of vitamins B1 and B2. Nebulization, oral supplementation, and topical application of Vitamin B complexes have demonstrated positive effects on tear secretion, corneal staining scores, nerve density, and the ocular surface environment.

More research is needed to understand the specific effects of each B vitamin on DED, but these findings underscore the potential of Vitamin B supplementation, especially in cases associated with neuropathic ocular pain []. The Blue Mountains Eye Study reported a higher prevalence of posterior subcapsular cataracts among users of high-dose thiamine and pyridoxine vitamin B6 supplements; however, the use of other B-vitamin supplements was associated with a reduced prevalence of nuclear and cortical cataracts [].

Thiamine is essential for nerve function and plays a role in energy metabolism. A deficiency can lead to vision disturbances and eye muscle weakness, possibly contributing to conditions like optic neuropathy []. Studies have shown mild ophthalmoparesis and bilateral symmetric vestibular loss in thiamine deficiency [].

Riboflavin is involved in energy production, metabolism, and the activation of other vitamins. It helps maintain healthy corneas and can guard against conditions like keratoconus [].

Deficiency may result in photophobia and eye discomfort, often associated with skin and mucous membrane issues []. Niacin plays a vital role in energy production and DNA repair, crucial for overall eye health; its deficiency may lead to pellagra, marked by dermatitis, diarrhea, dementia, and ocular issues like photophobia and blurred vision [].

Recent studies propose that nicotinamide, a Vitamin B3 form, could preserve retinal and optic nerve function in glaucoma. By boosting cellular energy and curbing oxidative stress, nicotinamide offers a potential avenue for glaucoma therapy.

It may also boost nitric oxide production, aiding in increasing aqueous humor outflow, regulating eye blood flow, reducing intraocular pressure, and safeguarding the optic nerve [,]. Nicotinamide differs from niacin in that it doesn't typically induce flushing as it doesn't act as a vasodilator [].

Additionally, while niacin effectively manages dyslipidemia, it's crucial to acknowledge reported cases of niacin maculopathy in patients undergoing treatment for hyperlipidemia []. Pyridoxine is involved in amino acid metabolism and neurotransmitter production.

It is essential for the normal development and function of the nervous system, including the visual pathways. According to findings from the Blue Mountains Eye Study [], individuals using high-dose thiamine and pyridoxine vitamin B6 supplements had a greater occurrence of posterior subcapsular cataracts [,].

In contrast, the consumption of other B-vitamin supplements was linked to a decreased prevalence of nuclear and cortical cataracts []. Folate is vital for DNA synthesis, repair, and cell growth. Adequate folate levels are important for the overall health of the retina and the optic nerve.

Supplementing with folic acid could serve as a protective therapy for individuals with retinal vascular conditions characterized by elevated homocysteine or glucose levels []. Vitamin B12 plays a crucial role in red blood cell formation, DNA synthesis, and neurological function.

Its deficiency can lead to anemia, affecting blood circulation to the eyes and optic nerve []. Studies suggest a link between its shortage and neurosensory issues, contributing to DED, which can be effectively addressed through supplementation to alleviate ocular neuropathic pain [,].

Additionally, Vitamin B12 supplementation in diabetic rats has shown benefits in reducing retinal hypoxia, excessive VEGF expression, and cell death in the retina []. However, it's worth noting that excessive intake of vitamin B12 may potentially contribute to the development of glaucoma [].

Vitamin C, a crucial water-soluble antioxidant, plays a vital role in supporting overall eye health by supporting collagen synthesis, essential for blood vessels, cornea, and vitreous structural integrity []. Abundant in the aqueous humor, it shields ocular structures like the lens [22,], and cornea from oxidative damage, regenerating vitamin E for enhanced antioxidant effects.

Present in human tears, it bolsters antioxidant and anti-inflammatory defenses on the ocular surface and aids in corneal wound repair [], reducing edema and inflammation in injuries caused by factors like ultraviolet B exposure, corneal alkali burns, or infectious keratitis [].

Zinc, a vital trace mineral, is crucial for retina health and preventing AMD, playing diverse roles in eye function. It serves as a structural element in retinal enzymes and proteins, supports antioxidant defense against oxidative stress present in SOD , aids immune function, promotes wound healing, contributes to night vision, and in combination with vitamins C and E, may reduce AMD risk [,].

However, it's worth noting that excessive Zn intake or exposure can impair immune function, lead to digestive issues, cause color vision deficiency decrease contrast sensitivity and eye irritation, and disrupt the balance of Cu in the body, which is essential for protecting the eyes from sunlight [].

Maintaining an adequate but not excessive intake of Zn is crucial for maintaining retinal health and supporting eye well-being. Patients who are deficient in Zn are highly vulnerable to optic neuropathy [].

Zinc-rich foods include a variety of legumes like black-eyed peas, kidney beans, and lima beans, as well as oysters, lean red meat, poultry, and fortified cereals.

Zinc absorption is lower in individuals consuming vegetarian diets; it is recommended that the Zn requirement for this group be twice as much as for nonvegetarians [,]. Selenium, crucial for cell protection, especially in the eyes via glutathione peroxidase, is vital for thyroid health and potentially aids in managing thyroid eye disease by reducing associated inflammation.

It might moderate the immune response targeting eye tissues in TED. Dietary sources include Brazil nuts, fish, poultry, and whole grains, with supervised supplements if intake is insufficient []. The European Group on Graves Orbitopathy explores selenium's role in TED, suggesting benefits for mild Graves' orbitopathy [].

However, while selenium plays a role in various selenoenzymes, excess amounts beyond what's necessary can be toxic and lead to cataracts in animals. Clinical evidence supporting selenium's protective role in ocular diseases is lacking due to suboptimal selenium intake not causing relevant deficiencies in the eye.

Copper plays a vital role in eye health, contributing to collagen formation, vascular maintenance, neurotransmitter synthesis dopamine, norepinephrine, and serotonin , and the structural integrity of ocular tissues.

Additionally, it is involved in melanin production, affecting pigmentation in the iris and RPE, providing UV radiation protection. Cu deficiency, as observed in Menkes disease, can lead to depigmentation of the iris and hair. Cu's presence in SOD supports antioxidant activity, safeguarding retinal cells from oxidative damage, which is particularly relevant in preventing conditions like AMD.

However, maintaining proper Cu balance is crucial, as excessive levels can be detrimental, emphasizing the importance of a balanced diet that includes Cu-rich sources like whole grains, legumes, nuts, and seafood [].

The accumulation of excess copper, whether due to a foreign body or Wilson's disease, can lead to deposition in different eye regions, resulting in tissue softening in the sclera, the development of a Kayser-Fleischer ring in the cornea, a greenish hue in the iris, sunflower cataracts in the lens, granular deposits in the vitreous, cellular alterations, and copper buildup in the retina.

These effects contrast with iron-induced changes and are less prone to causing degenerative retinopathy []. Iron deficiency, identified by signs like a pale appearance of the lower eyelid linings and an elevated vulnerability to eye infections, can indirectly affect eye health.

Iron plays a role in the upregulation of genes related to melanin production, as mentioned previously regarding the significance of melanin in the eye [35]. Iron plays a crucial role in the cornea's health, participating in processes like the citric acid cycle, ATP production, and DNA synthesis.

However, excess iron can lead to the formation of harmful oxygen-free radicals. Two key iron-related proteins in the tears are lactoferrin and ferritin, which are involved in iron transport, reducing oxidative damage, and bolstering antibacterial defenses.

Iron lines observed in the cornea, such as the Hudson-Stahli Line, Fleischer's Ring, Stocker's Line, and Ferry's Line []. Iron overload can lead to conditions like hemosiderosis bulbi, which is the accumulation of iron deposits in the anterior chamber.

Iron's involvement in cataractogenesis is also noted, particularly in cases of ocular siderosis and a genetic syndrome known as hereditary hyperferritinemia cataract syndrome HHCS , which is linked to elevated ferritin levels. Iron-catalyzed reactions and the formation of L-ferritin deposits within cataracts are considered potential mechanisms [].

In the retina, iron plays a crucial role in phototransduction but can also lead to toxicity if it accumulates excessively. Iron deposition in the retina can contribute to retinal degenerative diseases. Excess iron is also thought to contribute to AMD, a degenerative disease of the central retina that can result in vision loss.

AMD involves oxidative damage and inflammation, and increased iron levels have been detected in the retinas of AMD patients. Hereditary iron overload conditions such as aceruloplasminemia and hereditary hemochromatosis are also associated with retinal pathology, further suggesting the role of iron in retinal diseases [].

Diseases of the optic nerve, including ON, ischemic optic neuropathy, traumatic optic neuropathy, and glaucoma, can lead to retinal ganglion cell death, often through apoptosis and the generation of ROS.

While a direct link between excess iron and optic neuropathies is not established, iron's ability to produce highly reactive ROS may play a role in its pathogenesis.

Glaucoma, for example, is linked to increased oxidative stress and glutamate neurotoxicity, which may involve iron-related proteins []. Potential therapies for these eye diseases include antioxidants, iron chelators, and dietary iron limitation. Antioxidants, such as those found in the Age-Related Eye Disease Study, have shown promise in slowing the progression of AMD.

Iron chelators like deferiprone and deferasirox are being investigated for their potential to treat iron overload conditions and reduce iron-induced oxidative damage. Additionally, dietary iron limitation is being explored as a way to decrease lifetime iron stores and potentially reduce the risk of retinal degeneration [].

Magnesium is a versatile mineral crucial for a wide range of physiological functions, including its participation in over enzyme systems responsible for processes such as protein synthesis, muscle contraction, and nerve function.

It plays a pivotal role in energy production and nucleic acid synthesis, contributing to cellular well-being []. In the context of eye health, Mg is mainly found in eye structures like the cornea, lens, retina, vitreous body, and anterior chamber, where it helps maintain structural integrity and function.

It is also associated with a reduced risk of cataract formation and potential prevention of glaucoma [,]. Moreover, Mg is vital for cardiovascular health, influencing blood flow and offering neuroprotective effects.

Its role in maintaining nerve function, including the transmission of visual signals from the eye to the brain via the optic nerve, underscores its significance for overall eye health []. Mg-rich foods like nuts, seeds, and leafy greens are valuable dietary sources to support these functions [].

While calcium deficiency doesn't have a direct influence on eye health, severe deficiencies may be associated with the development of cataracts [].

Band-shaped keratopathy affects the cornea, causing calcium and phosphate buildup, resulting in whitish or grayish bands that hinder vision. Elevated blood calcium levels, particularly in conditions like systemic hyperparathyroidism and Vit-D toxicity, including hyperparathyroidism affecting the parathyroid glands, are associated with this condition and contribute to heightened calcium levels in the body [].

Pseudoxanthoma elasticum PXE , a genetic condition impacting connective tissues, especially elastic fibers, involves calcium in abnormal mineralization, leading to deposits in diverse tissues and characteristic changes in the skin, eyes, and cardiovascular system.

The unclear mechanisms behind calcium's role in PXE relate to disrupted calcium metabolism, highlighting the necessity for comprehension to devise precise therapies and ongoing exploration of associated molecular and cellular pathways []. Adjusting calcium levels within the Bruch membrane might offer potential treatments to mitigate Bruch membrane disruption and decrease the occurrence of choroidal neovascularization CNV in conditions such as myopia, PXE, or AMD.

In Cancer-associated retinopathy, the calcium-binding protein recoverin is pivotal [], while in ocular melanoma, the reduction of the pro-apoptotic calcium-binding protein ALG-2 contributes to pathogenesis []. Calcium-based materials show potential in boosting anti-cancer immunity.

Disruption in maintaining calcium homeostasis in photoreceptors results in retinal dysfunction and the onset of pathologies leading to blindness. Additionally, calcium plays a role in transmitting optic nerve signals, including those along the optic nerve. This may play a role in glaucoma pathogenesis [].

Phytochemicals, synthesized by plants as a defense against fungi, bacteria, and plant viruses, and consumed by insects and animals, are categorized into different subclasses, each offering specific benefits for ocular health [].

Carotenoids, responsible for the red, orange, and yellow hues in fruits and vegetables, serve as antioxidants and supply vitamin A. Meanwhile, lutein and zeaxanthin, found in high concentrations in the retina, shield against high-energy light, decreasing the risk of cataracts and AMD [].

Polyphenols, encompassing flavonoids, phenolic acids, and polyphenolic amides renowned for their antioxidant traits, are found in food items like tea, berries, and dark chocolate.

Certain flavonoids, like quercetin and rutin, deliver antioxidant and anti-inflammatory advantages, reducing the risks associated with cataracts and AMD []. Anthocyanins present in dark fruits improve night vision and promote general eye health [].

Glucosinolates in cruciferous vegetables shield the eyes from oxidative harm, while phenolic acids like chlorogenic acid, found in coffee, might lower the risk of eye ailments [].

Terpenes containing essential oils in herbs such as rosemary and thyme enhance blood circulation and offer protection against oxidative stress [].

Saponins and plant sterols sourced from legumes aid in lowering LDL cholesterol levels and contribute to eye health, while tannins present in tea and red wine act as antioxidants and anti-inflammatories [], offering protection for the eyes.

Alkaloids like caffeine, found in coffee and tea, enhance retinal blood flow, promoting better eye health []. Phytochemicals have also shown significant potential in eradicating bacterial biofilms without causing substantial harm to mammalian fibroblast cells.

This promising trait suggests a potential solution for combating multidrug-resistant bacterial infections []. Incorporating these phytochemical-rich foods into one's diet can significantly enhance eye health and potentially reduce the risk of eye-related conditions such as cataracts, glaucoma, and AMD, though further research is needed.

Beta-carotene recognized as a precursor to vitamin A and an antioxidant with potential eye health benefits, is renowned for its role in diminishing the likelihood of cataracts and age-related eye conditions []. This compound undergoes conversion into retinol within the eye, promoting optimal night vision.

The notable AREDS1 trial presented compelling evidence of its favorable effects when combined with vitamins C and E, Zn, and Cu, leading to a reduced risk of advanced AMD []. Cohort studies additionally endorse the consumption of specific vitamins and carotenoids in mitigating the risk of age-related cataracts [].

While a higher dietary intake of beta-carotene is widely regarded as safe, it is advisable to exercise caution when exceeding typical dietary levels, particularly for individuals at risk of lung cancer.

Notably, in smokers, substantial beta-carotene supplementation has been unexpectedly linked to an increased risk of lung cancer, ascribed to its pro-oxidant effects in an oxidative stress environment characteristic of a smoker's lung [].

Lutein and zeaxanthin are the only carotenoids found in the human lens and retina, with high concentrations in the macula of the retina, where they serve as both antioxidants and optical filters, safeguarding the retina from the harmful effects of high-energy light, including blue and ultraviolet light [24].

Their association with a reduced risk of cataracts and AMD underscores their protective role for the macula, potentially benefiting individuals with diabetic macular edema [].

These carotenoids are prominently found in leafy greens such as spinach and kale. This underscores the advantages of supplementation [60,]. Astaxanthin, a xanthophyll, and member of the carotenoid group, is known for imparting red and pink colors to aquatic animals, birds, and microorganisms [].

It serves as a potent natural antioxidant with anti-inflammatory and anti-apoptotic properties, making it valuable in cancer prevention and eye disease protection []. It stands out by working throughout the cellular membrane, offering defense against oxidative stress from reactive oxygen species in both inner and outer membrane layers.

Clinical trials have shown its potential in enhancing eye health, yielding promising results in conditions like dry eye syndrome, keratitis, cataracts, DR, AMD, high intraocular pressure, and glaucoma []. Crocin, a water-soluble carotenoid and a primary compound in saffron is responsible for the spice's distinct red color.

It possesses antioxidant properties, protecting eye cells and tissues from oxidative stress and inflammation. These properties make it a candidate for reducing the risk of eye conditions such as AMD and cataracts.

Saffron also contains other carotenoids like zeaxanthin and lycopene, contributing to its potential benefits for eye health. Although saffron is commonly used in cooking, it can also be taken as a dietary supplement for its potential eye health advantages, with further research needed to establish its full effectiveness [].

Lycopene, a natural carotenoid found in red fruits and vegetables like tomatoes and watermelon, provides their distinctive red color. It serves as a potent antioxidant with potential health benefits, including supporting eye health and reducing the risk of AMD and cataracts [,]. Phenolic compounds are a specific class of phytochemicals.

They are characterized by the presence of a phenol group in their chemical structure. This group includes compounds like flavonoids, lignans, and stilbenes. Phenolic compounds are known for their antioxidant and anti-inflammatory properties and are found in a variety of plant-based foods, such as fruits, vegetables, tea, and whole grains.

They are often associated with the health-promoting effects of a diet rich in fruits and vegetables [,]. Cinnamon contains cinnamaldehyde, a key component responsible for its flavor and potential health benefits. This natural organic phenolic compound, along with other compounds like cinnamic acid and cinnamyl alcohol, contributes to cinnamon's unique aroma.

Studies have examined cinnamon leaf oil and its antioxidant properties, as well as its ability to inhibit metabolic enzymes like carbonic anhydrase II hCA II , acetylcholinesterase AChE , and α-amylase, which are linked to conditions such as diabetes, Alzheimer's disease, cataracts, and glaucoma [,].

Certain flavonoids like quercetin and rutin have antioxidant and anti-inflammatory properties that can benefit eye health by reducing the risk of cataracts and AMD, along with conditions such as DED and uveitis [].

Certain flavonoids display promising antiviral properties []. Flavonoids function as antioxidants through a variety of molecular mechanisms. Firstly, they directly interact with free radicals, utilizing their free hydroxyl group s to neutralize these harmful molecules.

These metal-binding sites within flavonoids are typically located near their hydroxyl and ketone side groups. Lastly, flavonoids play a role in regulating multiple cellular antioxidant systems, helping to restore the cellular redox balance following periods of oxidative stress.

Beyond their antioxidant properties, flavonoids also influence inflammation by modulating key mediators such as AP-1, NFκB, STAT3, and nitric oxidases, particularly iNOS and nNOS. Quercetin, a natural flavonol antioxidant found in various plant sources, has shown therapeutic potential for treating various eye-related issues due to its antioxidant, anti-inflammatory, and anti-fibrosis activities.

It may help with conditions like KC, TED, DED, ocular surface problems, cataracts, glaucoma, retinoblastoma, and other retinal diseases [,]. Oral administration of forskolin and rutin can contribute to improved intraocular pressure control in patients with limited responsiveness to multiple treatments [,].

Flavonoids also aid in maintaining healthy blood vessels in the eyes, crucial for preventing DR [,]. Anthocyanins, a type of flavonoid found in dark-colored fruits like blueberries and grapes, have unique antioxidant properties that can enhance night vision and overall eye health [].

Bilberry, rich in anthocyanins, offers antioxidant, genoprotective, anti-cancer, anti-inflammatory, and cardioprotective effects, making it valuable in preventing age-related conditions such as cardiovascular disease and cancer, managing type 2 diabetes, and lowering lipid levels [,].

It has a traditional use for promoting eye health, potentially benefiting cataracts, retinopathy, macular degeneration, and night vision []. Bilberry also exhibits impressive antimicrobial properties, which are significant in the context of growing antibiotic resistance [,].

While bilberry's anthocyanins hold promise for overall health improvement, comprehensive exploration of their potential across various health domains requires further research, especially through controlled human trials.

Common dietary sources of flavonoids include tea, citrus fruits, berries, red wine, apples, and legumes []. Curcuminoids, a polyphenolic class present in turmeric's rhizome, notably curcumin or diferuloylmethane, boast diverse pharmacological traits like antioxidative, anti-inflammatory, antimicrobial, and anticancer effects.

Its potential extends to significant eye conditions such as corneal neovascularization, wound healing, DED, conjunctivitis, pterygium, glaucoma, cataracts, AMD, DR, and anterior uveitis, as explored in various studies. The main constraint of curcumin lies in its limited bioavailability, with only a minimal fraction of the substance reaching the bloodstream in a biologically active form [].

Resveratrol, a polyphenol found in grapes, red wine, grape juice, peanuts, cocoa, and certain berries, though a minor component in red wine compared to other polyphenols, has garnered attention in eye research.

Studies highlight its diverse positive effects, including antioxidative, anti-apoptotic, anti-tumor, anti-inflammatory, anti-angiogenic, and vasodilatory properties. These traits have been examined concerning eye conditions like glaucoma, cataracts, AMD, and DR.

Yet, further research is necessary to better understand its clinical benefits [,]. Terpenes, plant-based compounds responsible for unique scents and flavors, play a vital role in cannabis and its therapeutic effects. While smoked marijuana can temporarily reduce eye pressure, the effects are brief, requiring frequent use for continuous reduction [].

Specific terpenes like myrcene, with its peppery scent, aid in pain relief and relaxation []. Caryophyllene, found in pepper and cloves, shows promise in reducing inflammation, anxiety, and depression [].

Terpenes like alpha-pinene and limonene, reminiscent of pine and citrus, respectively, exhibit anti-inflammatory properties and potential benefits for eye conditions like glaucoma []. However, oxidation products of terpenes, such as limonene, may contain irritants contributing to reported eye and airway issues indoors [].

Ginkgo biloba extract GBE , containing flavonoids and terpenoids, demonstrates antioxidant properties, potentially protecting eye cells from oxidative stress []. Research indicates its potential in addressing various eye conditions like AMD, retinal diseases, and glaucoma by supporting retinal health, reducing damage, and enhancing blood flow [].

While generally well-tolerated, caution and professional guidance are advised for GBE use due to potential side effects and interactions, necessitating further research for a comprehensive understanding of its benefits in eye health. The presence of organosulfur compounds in certain foods has been linked to improved eye health, attributed to their antioxidant and anti-inflammatory properties [].

Vegetables belonging to the Brassica genus, such as broccoli, contain sulforaphane, a potent antioxidant that may reduce the likelihood of developing AMD []. Allium species, including garlic, contain alliin and allicin, two organosulfur compounds that exhibit both antioxidant and anti-inflammatory activities [].

Protein-rich foods often contain sulfur-containing molecules, such as glutathione and methionine, which contribute to antioxidant defenses and protect the sensitive cells of the lens and retina [,].

Additionally, taurine, an amino acid found in many animal products, has been shown to mitigate oxidative stress within the retina []. S-adenosylmethionine SAMe , a naturally occurring sulfur-bearing compound, plays a regulatory role in various biochemical processes vital to eye health [].

ALA, also known as lipoic acid, is a vital antioxidant organosulfur compound, involved in energy production and is sourced from various foods like organ meats, spinach, and broccoli [].

ALA can be obtained through oral supplementation and intravenous injection and has shown promise in managing conditions such as diabetes, neuropathy, and ischemic-perfusion injury. It has demonstrated potential in preventing DED by reducing matrix metalloproteinase-9 expression and maintaining ocular surface antioxidant status.

Furthermore, ALA can protect against DR by inhibiting various factors and alleviating oxidative stress []. ALA has also been linked to improved near-visual acuity by reducing disulfide bonds in lens proteins and enhancing the dynamic refractive power of the lens during accommodation [].

Habitual indulgence in certain substances coffee, tea, alcohol, and cigarette smoking can have both positive and negative effects on eye health. Individual habits should be moderated to prevent potential negative effects [,].

Habitual tea drinking can have varying effects on eye health. The type of tea, toxin presence, and consumption level are all factors. Green tea, rich in antioxidants rich in catechins, particularly epigallocatechin gallate EGCG , can reduce the risk of cataracts and macular degeneration [,].

Some studies even suggest caffeine might protect against dry AMD and enhance overall eye function []. Herbal teas, like chamomile and calendula, help with hydration, benefiting DED. They may also have anti-inflammatory properties, helpful for conditions like Meibomian Gland Dysfunction MGD and DED [].

Consumption of coffee and tea, particularly cups of coffee and more than 4 cups of tea per day, is associated with increased macular retinal nerve fiber layer mRNFL thickness, suggesting potential neuroprotective effects that warrant further investigation into causal links and mechanisms [].

However, high caffeine intake from teas like black or green tea can lead to dehydration and potentially increase intraocular pressure, a glaucoma risk [].

Caffeine can act as a diuretic, potentially causing fluid loss and increased urination. Caffeine-sensitive individuals should choose caffeine-free herbal teas or decaffeinated versions and maintain overall hydration [].

A moderate dose of caffeine enhances rapid eye movements' kinematics, such as saccade velocities and quick phases of optokinetic nystagmus, in unfatigued individuals, without affecting pursuit eye movements or visual perception, suggesting that caffeine's influence on oculomotor control may be mediated by changes in central catecholamines even in non-fatigued conditions [].

Teas may contain trace amounts of heavy metals, but high-quality teas in moderation usually don't pose a significant eye health risk. In summary, moderate tea consumption, especially green tea with its antioxidants, can benefit eye health, reducing AMD and cataract risk.

Still, excessive caffeine-rich tea consumption should be avoided. Quality and toxin presence in tea should be monitored [,]. The effects of alcohol, including red wine, on eye health and associated conditions vary. While some compounds in red wine may have potential benefits for conditions like AMD, it's crucial to maintain moderation in alcohol consumption to reduce the risk of negative eye-related effects [].

Alcohol intoxication, whether from binge drinking or moderate consumption, primarily affects the central nervous system and can lead to visual disturbances, including impaired color perception, decreased contrast sensitivity, and abnormal eye movements.

It can also result in subclinical changes in eye movements, such as prolonged fixation latency and increased saccades []. Fetal Alcohol Syndrome FAS is associated with ocular findings that serve as markers for teratogenesis.

Fully developed FAS cases often exhibit more pronounced ocular manifestations. Alcohol's impact on the eye involves transcription factors like Pax6 and Otx2, retinoic acid signaling, and oxidative and nitrogen signaling. Ocular abnormalities in FAS include various physical characteristics like short palpebral fissures, epicanthus, and microphthalmia, as well as optic disc hypoplasia and retinal vasculature tortuosity.

Ocular examinations are crucial for diagnosing and managing eye conditions in FAS cases, and ion channel modulation is being explored as a potential treatment []. Alcohol consumption can have mixed effects on eye health.

It's associated with an increased risk of AMD due to oxidative pathways and reduced intake of protective nutrients like Zn and vitamins [].

The relationship between alcohol and DR is still unclear, with some studies showing conflicting results.

Alcohol consumption can also impact retinal vein occlusion RVO , possibly through factors like hyperviscosity and dehydration []. Central serous chorioretinopathy CSCR can be linked to alcohol consumption, affecting choroidal blood vessels []. Chronic alcohol intake may lead to optic neuropathy characterized by central or cecocentral scotomas and color vision defects, which can be managed by reducing alcohol intake and providing vitamin supplementation [].

Alcohol's relationship with glaucoma remains a topic of debate, with some studies suggesting an association and others hinting at a potential protective effect [].

Heavy alcohol consumption increases the risk of age-related cataracts, likely due to the generation of free radicals and disturbances in lens calcium levels []. Alcohol can also affect the ocular surface, with some studies suggesting a link to DED and increased tear osmolarity, while others show contradictory results.

A recent meta-analysis indicates that alcohol consumption can increase the risk of DED, possibly due to ethanol-induced inflammation in ocular surface cells. Chronic alcoholism can lead to vitamin A deficiency, contributing to keratinization and DED [].

Additionally, alcohol, particularly red wine, can trigger ocular migraines, causing temporary vision disturbances []. It is also a common trigger for rosacea flare-ups, a skin condition that can affect the eyes, leading to redness and irritation [].

Choosing between natural supplements and a balanced diet, or multivitamins and minerals, involves a trade-off between customization and convenience. Natural supplements and a balanced diet offer the advantage of targeting specific nutrients, minimizing additives, and enabling customization to individual nutritional needs, but they may require more planning and potentially cost more.

In contrast, multivitamins and minerals provide a simplified, cost-effective means of obtaining a wide spectrum of essential nutrients but may deliver unnecessary elements and exhibit variability in quality []. Obtaining therapeutic levels of essential nutrients for eye health through a balanced diet can be challenging due to the need for large food quantities, which can have adverse effects from other components.

For instance, achieving high doses of omega-3 fatty acids solely from fish could lead to excess mercury intake, so omega-3 supplements with controlled doses are a safer option [].

Similarly, for vitamin D, supplements can be more reliable than trying to get therapeutic levels through excessive sun exposure, which may increase the risk of skin damage []. The use of chemical compounds in medication doesn't imply an unnatural approach.

Instead, it involves isolating the active substance in a precise dosage, which helps prevent side effects resulting from excessive consumption of other potentially unnecessary or toxic ingredients. Many pharmaceutical drugs have their origins in natural and herbal sources, and the utilization of chemical compounds in medications represents a focused and refined approach to harnessing their therapeutic properties.

For instance, metformin, a widely prescribed medication for managing type 2 diabetes, finds its roots in the French lilac plant Galega officinalis. It has been developed to help regulate blood glucose levels effectively [].

Atropine, derived from the deadly nightshade plant Atropa belladonna , has been employed for its anticholinergic properties and is used in ophthalmology to dilate the pupil for various diagnostic and treatment purposes.

These drugs exemplify how modern medicine can draw from the natural world while ensuring precise dosages and minimizing potential side effects associated with consuming the whole plant or herb.

This approach combines the best of both worlds by integrating the benefits of herbal remedies with the rigor of pharmaceutical science []. The Mediterranean diet MD is renowned for its substantial health benefits and environmental sustainability.

It has consistently shown a strong association with increased longevity and a reduced risk of various age-related ailments, including cancer, dementia, and cardiovascular diseases []. Although the precise definitions of the MD may exhibit slight variations, they all emphasize core elements: a generous consumption of plant-based foods such as vegetables, nuts, cereals, fruits, and legumes, with olive oil as the primary source of dietary fat.

Additionally, the diet encourages moderate intake of dairy products, poultry, red wine, and fish, while discouraging the consumption of red meat and sweets. The combined impact of these dietary components, with their synergistic effects and interactions, is believed to underlie the MD's profound positive effects on eye health.

The MD can help prevent chronic age-related eye diseases, including cataracts, glaucoma, AMD, DR, and DED [3]. While multivitamin and mineral supplements are generally safe and provide vital nutrients that can promote overall well-being, including eye health, it's important to be cautious about excessive or prolonged consumption of certain vitamins and minerals in these supplements, which can potentially result in side effects affecting the eyes.

For instance, consuming too much vitamin A can lead to a condition known as hypervitaminosis A, associated with intracranial hypertension and papilledema.

Symptoms of vitamin A toxicity may encompass blurred vision and double vision 6th nerve palsy []. Certain antioxidants like anthocyanins and xanthophylls have not shown adverse health effects, while others, such as β-carotene, must be consumed cautiously.

Provitamin A carotenoids offer a safer alternative. Despite having provitamin A activity, the upper limit for β-carotene remains inconclusive []. High doses of B-vitamin supplements have been linked to an elevated risk of cataracts [].

Excessive intake of vitamin E may increase the risk of bleeding disorders, which, while not directly impacting the eyes, can lead to increased eye bleeding following an injury [].

Similarly, excessive Zn intake can disrupt Cu absorption, potentially causing reduced Cu levels in the body []. Cu is essential for the production of melanin in the eyes, which safeguards them from sunlight. A deficiency in Cu can result in light sensitivity and a heightened risk of eye damage from exposure to ultraviolet UV light.

Moreover, excessive iron intake carries the potential for oxidative damage, with increased iron accumulation believed to contribute to AMD [].

Excess Cu levels may manifest in Wilson's disease WD , characterized by Kayser-Fleischer rings, sunflower cataracts, disruptions in retinal function, and effects on visual systems and eye mobility [].

Among other vitamins, vitamin C has the lowest toxicity, although excessive consumption can impact gastrointestinal and renal function [18]. While Se can offer benefits, chronic exposure can lead to toxicity, primarily affecting endocrine and neurological functions [].

There is limited evidence to suggest that multivitamin use has a cancer-preventive effect, except for colon cancer, in both men and women participating in the NIH-AARP Diet and Health Study. However, in men, increased multivitamin use was associated with slightly higher risks of overall, prostate, and lung cancer, as well as leukemia.

Additionally, women showed a higher risk of oropharyngeal cancer with greater multivitamin use []. Establishing tolerable upper intake levels and recommended daily intakes for vitamins and minerals to safeguard against complications is necessitated. Nutritional recommendations serve as a potent tool for preventing and managing a range of eye diseases, ultimately contributing to the enhancement and preservation of one's vision.

We have compiled prevalent nutritional and supplement guidelines for addressing different conditions that impact eye and vision health. Adherence to a Mediterranean diet has been linked to a reduced risk of AMD progression.

In contrast, an Oriental diet pattern is associated with a lower prevalence of AMD, while a Western diet pattern is linked to a higher prevalence. Consuming a diet rich in vegetables with carotenoids and fatty fish containing omega-3 fatty acids can be beneficial for individuals at risk of AMD.

On the other hand, it's advisable to minimize the consumption of vegetable oils and animal fats rich in omega-6 fatty acids, as well as red and processed meats, to lower the risk of AMD progression.

High-glycemic index diets and excessive alcohol intake, exceeding two drinks per day, are also associated with an increased risk of AMD. It's essential to recognize that the quality of one's diet and food choices plays a pivotal role in AMD, highlighting the importance of providing appropriate nutritional advice to individuals at risk [].

Prominent large clinical trials in eye health, primarily focused on AMD, include the Age-Related Eye Disease Study AREDS and its subsequent study, AREDS2 [], as well as the Nutritional AMD Treatment 2 NAT2 [], and National Eye Institute NEI -supported AMD studies [], collectively enhancing our knowledge of the influence of supplements, nutrients, vitamins, and minerals, notably in the context of AMD.

These supplements typically include antioxidants like vitamins C and E, Zn, and Cu, as well as the carotenoids lutein and zeaxanthin. The AREDS studies have shown that these supplements can slow the progression of AMD in some individuals and are often recommended as part of a comprehensive approach to managing the condition [].

Cataracts can be influenced by factors such as metabolic diseases, nutrition, diet, and specific vitamins and minerals. The original AREDS formulation did not provide protective effects against cataract development, and beta-carotene has been associated with increased risks of lung cancer in smokers and hip fractures in women [].

Protective nutrients include antioxidants like vitamin C, vitamin E, and Zn , found in foods such as citrus fruits and nuts, lutein and zeaxanthin in leafy greens, omega-3 fatty acids in fatty fish, and vitamin A sourced from carrots and sweet potatoes [].

Conversely, saturated and trans fats, excessive alcohol, high-sugar and high-glycemic-index foods, and metabolic diseases like diabetes and obesity can increase cataract risks, making proper management through diet, exercise, and medication vital for risk reduction [].

Several supplements exhibit potential in managing glaucoma. These compounds leverage various mechanisms, including antioxidant, anti-inflammatory, and anti-apoptotic properties.

Baicalein, forskolin, marijuana, ginsenoside, resveratrol, and hesperidin have proven capable of reducing intraocular pressure []. Ginkgo biloba, Lycium barbarum, Diospyros kaki, Tripterygium wilfordii, saffron, curcumin, caffeine, anthocyanin, CoQ10, and vitamins B3 and D have displayed neuroprotective effects on retinal ganglion cells [].

Omega-3 fatty acids found in fish oil supplements possess anti-inflammatory attributes, potentially improving ocular blood flow and decreasing intraocular pressure []. Antioxidants like vitamin C protect the optic nerve, while vitamin E shields retinal ganglion cells from oxidative stress []. Magnesium supplements aid in blood vessel relaxation and circulation, showing promise in preventing ganglion cell loss and serving as a potential candidate for glaucoma management [,].

Additionally, extending citicoline treatment for up to 8 years has shown potential in stabilizing or enhancing glaucomatous visual function, hinting at citicoline's neuroprotective effects in glaucoma []. Nevertheless, extensive future studies are needed to ascertain the efficacy and safety of natural products as alternative therapies for glaucoma.

Emerging research indicates that nicotinamide, a form of vitamin B3, shows promise in managing glaucoma. Nicotinamide's neuroprotective properties have gained attention for their potential to safeguard retinal ganglion cells and optic nerve function, both commonly compromised in glaucoma [].

By enhancing cellular energy production and reducing oxidative stress, nicotinamide may offer a valuable avenue for preserving vision in glaucoma patients, representing a novel and promising aspect of glaucoma therapy []. It plays a role in regulating intraocular pressure in the eye through its potential complex interaction with nitric oxide, a crucial signaling molecule affecting blood vessel dilation.

In the context of ocular health, nitric oxide can influence eye pressure regulation []. Studies have suggested that niacin may enhance nitric oxide production, contributing to improved blood flow and a potential reduction in intraocular pressure []. This suggests that nicotinamide may hold promise as a supplement for individuals with conditions like glaucoma, where elevated eye pressure can be a concern.

However, further research is required to fully comprehend the mechanisms and therapeutic implications. On the other hand, it's worth noting that high caffeine intake may lead to a slight increase in intraocular pressure mmHg in individuals with glaucoma, making it advisable to limit caffeine consumption [,].

It's important to emphasize that, while these supplements hold promise, they should not replace conventional glaucoma treatments prescribed by healthcare professionals. In addition to traditional treatments for diabetic patients, research is exploring the potential advantages of particular dietary approaches and supplements to prevent, manage, or delay the advancement of DR.

Emphasis is placed on the use of antioxidants such as vitamins C and E, omega-3 fatty acids, and Zn. Furthermore, dietary plans like the Mediterranean diet and low-glycemic diets are being investigated and recommended as potential strategies in this context [].

Nutrition plays a significant role in ocular surface health, particularly concerning dry eye syndrome. Several nutrients have protective effects on the ocular surface, such as omega-3 and omega-6 fatty acids for reducing inflammation, vitamin D for dry eye risk reduction and recovery enhancement, vitamin A supporting the corneal epithelium, vitamin B12, and citicoline improving ocular surface health, vitamin C protecting the eye's tear film, and vitamin E for oxidative stress reduction and corneal healing.

Herbal teas like chamomile and calendula contribute to hydration and possess anti-inflammatory properties. Conversely, excessive caffeine and alcohol consumption can lead to dehydration and worsen dry eye symptoms, while high salt intake and excessive vitamin A supplementation can have adverse effects [].

Diets rich in saturated and trans fats are associated with a higher risk of dry eye syndrome, emphasizing the importance of a balanced diet for maintaining ocular surface health [].

The well-being of meibomian glands, the small oil-producing glands in the eyelids, is crucial for maintaining a stable tear film and preventing dry eye syndrome.

Although nutrition may not directly impact these glands, specific dietary habits and nutrients can indirectly benefit the meibomian glands. Omega-3 fatty acids can enhance meibomian gland function, while vitamin A supports the entire ocular surface, including the meibomian glands [].

Notably, vitamin A deficiency VAD is linked to chalazion in young children. Exposure to cis retinoic acid cis RA , a vitamin A metabolite, is one of the risk factors for meibomian gland dysfunction MGD , although the precise mechanisms are not fully understood.

It is hypothesized that cis RA may hinder cell proliferation, promote cell death, alter gene and protein expressions, and diminish cell survival pathways in human meibomian gland epithelial cells. Additionally, oral vitamin D supplementation has been shown to enhance meibomian gland expressibility in MGD patients with vitamin D deficiency [].

While nutrition can contribute to meibomian gland health, it's worth noting that high-fat diets may harm meibomian gland function []. Using vitamin A eye drops has demonstrated moderate effectiveness in managing SLK []. However, the role of systemic vitamin A and Se in the management of SLK remains uncertain and has not been established definitively.

For cases involving stromal melting that do not respond to standard treatment, including doxycycline and medroxyprogesterone, healthcare providers may recommend the use of NAC and a daily oral vitamin C 1, mg supplement [,]. Selenium has been investigated for its potential role in managing TED.

Multiple studies have indicated that Se supplementation could potentially benefit the condition, though the precise mechanisms remain incompletely understood. It is essential to avoid excessive iodine intake, commonly found in iodized salt and seaweed, as it can exacerbate thyroid disorders, including TED [].

Obesity is a well-established risk factor in developed countries, and diets contributing to obesity may lead to nutritional deficiencies associated with the clinical symptoms of Idiopathic Intracranial Hypertension IIH [].

Some vitamin A metabolite levels differ in IIH patients compared to obese individuals. Intracranial pressure ICP elevation and ON have been linked to the use of isotretinoin. Acetazolamide, a proven IIH therapy, appears to affect vitamin A metabolism.

Limited data exists on dietary modifications for IIH treatment, but limiting vitamin A-rich foods like tomatoes, carrots, sweet potatoes, leafy greens, fish, and eggs may be beneficial [].

Patients with IIH or unexplained optic disc swelling should be screened, investigated, and treated for possible deficiencies in vitamins A, B1, and B12 [].