The Eye Health Guide: What Screens, Age and Supplements Actually Do

Most eye supplements are sold to people whose eyes feel tired after a day at a screen. Most of the evidence behind those supplements comes from a completely different group: people over 50 with a diagnosed, intermediate stage of age-related macular degeneration, studied in a government trial that ran for five years. That gap, between who buys eye vitamins and who was actually studied, is the whole story of this guide. We will go through what happens to your eyes, which popular ingredients have weak evidence, which have real evidence and at what dose, and then read the labels of the products people actually buy and compare the number on the panel with the number in the trial.

One promise up front, which is really a non-promise. Nothing in this guide brings back vision that has been lost, changes a glasses prescription, clears a cataract, or lowers eye pressure. If a product says it does, that is the first thing to be suspicious of.

What is actually happening to your eyes

Light passes through the cornea and the lens, and the lens changes shape to focus objects at different distances, a process called accommodation. The image lands on the retina, and the finest part of it lands on the macula, a patch of retina a few millimeters across that carries most of the cone photoreceptors and does the detailed work: reading, faces, screens. Behind the photoreceptors sits a layer of support cells that recycles the light-sensitive pigments and clears waste. Everything a supplement could plausibly do for the eye happens in one of these places.

Three separate things get lumped together as "my eyes are bad" and they need to be pulled apart, because they have different causes and different answers.

Digital eye strain

When you look at something close, the ciliary muscle inside the eye contracts to thicken the lens, and the two eyes turn inward to keep the image single. Hold that for hours and the muscle fatigues in the ordinary way muscles do. At the same time, concentration on a screen lowers the blink rate and produces more incomplete blinks, so the tear film that keeps the front of the eye smooth and wet thins and breaks up between blinks. Sheppard and Wolffsohn's 2018 review in BMJ Open Ophthalmology describes exactly this combination: an accommodative and vergence load from sustained near work, plus a reduced and incomplete blink pattern that dries the ocular surface, plus glare and poor contrast. The symptoms are burning, grittiness, blur that clears with blinking, headache around the brow, and difficulty refocusing at distance after a long stretch of near work.

Two points matter for what follows. First, digital eye strain is a fatigue and surface-dryness problem, not a retina problem. It is uncomfortable but it does not damage the eye, and it usually settles overnight. Second, the responses that make sense are the ones that address fatigue and dryness: breaks that let the ciliary muscle relax, deliberate blinking, humidity, lighting and screen position. There is no nutrient whose deficiency causes screen fatigue, so there is no supplement that corrects it, although most "eye vitamins" are sold as if there were.

Refractive error and myopia

Blur at distance (myopia), at near (hyperopia), or from an unevenly curved cornea (astigmatism) is a question of the eye's optics, not its nutrition. The eyeball is slightly too long or too short for its lens, and glasses, contact lenses or surgery correct the optics. No supplement changes the length of the eye or the curve of the cornea. The one nutrition-adjacent finding here concerns children, not adults, and it is not about a nutrient: a 2017 meta-analysis in Acta Ophthalmologica (Xiong and colleagues) found that more time spent outdoors was associated with a lower chance of a child becoming myopic in the first place, although it did not slow progression in children who were already myopic. The working explanation is bright outdoor light and distance viewing, not anything you swallow. For children, that is the eye-health intervention with the best cost-to-evidence ratio in this guide, and it is free.

Age-related macular degeneration

This is the condition almost all of the supplement evidence is about. With age, waste deposits called drusen accumulate under the macula, the support layer thins, and in the advanced stages either the central photoreceptors atrophy (dry AMD) or abnormal blood vessels grow under the retina and leak (wet AMD). The result is loss of central vision, which is exactly the vision you use to read and recognize faces. AMD is graded on a dilated eye exam: early, intermediate and advanced. The intermediate stage is where the National Eye Institute's Age-Related Eye Disease Studies (AREDS and AREDS2) found that a specific high-dose antioxidant and zinc formula reduced the chance of progressing to the advanced stage. It is important to hold on to the specifics: an effect on the rate of progression, in people already at the intermediate stage, on a formula taken for years. AREDS did not study healthy eyes, tired eyes or screen use, and it did not find that anyone's vision came back.

The macula is also where lutein and zeaxanthin come in. These two carotenoids are the only ones the body concentrates in the macula, where they form the yellow macular pigment, which absorbs short-wavelength blue light before it reaches the photoreceptors and quenches the reactive oxygen species that light exposure produces. The body cannot make either, so what reaches the eye comes from diet (leafy greens, egg yolk, corn) or a supplement, and, unusually for a supplement ingredient, the amount in the macula can be measured directly as macular pigment optical density. That measurability is why lutein is the most solid part of this guide.

Dry eye, cataract and glaucoma, briefly

Dry eye is a tear-film disorder that overlaps with digital eye strain but also has its own causes: age, hormones, certain medications, eyelid gland dysfunction. Cataract is clouding of the lens itself; it is corrected surgically and no supplement clears one. Glaucoma is damage to the optic nerve, usually with raised eye pressure, managed with pressure-lowering drops, laser or surgery. Products are sold "for" all three. For dry eye the largest trial of the most popular supplement was negative, and for cataract and glaucoma the supplement evidence in humans is thin to absent.

What does not work, or works much less than the label suggests

Bilberry for night vision. The story that Royal Air Force pilots ate bilberry jam to see at night is a story, and the trials do not back it. A 2004 systematic review in Survey of Ophthalmology (Canter and Ernst) went through the placebo-controlled trials of bilberry anthocyanosides for night vision and found that the more rigorous ones showed no effect. Bilberry is harmless and pleasant; it is not a night-vision supplement.

Beta-carotene "eye vitamins" if you smoke or used to smoke. The original AREDS formula contained 15 mg of beta-carotene. Two large trials in the 1990s, including the ATBC study in more than 29,000 male smokers published in the New England Journal of Medicine in 1994, found that beta-carotene supplements increased lung cancer incidence in smokers rather than reducing it. That is the reason AREDS2 tested lutein and zeaxanthin as a replacement, and the reason the formula sold today has no beta-carotene. Some cheaper eye vitamins still use it. If you smoke, or smoked, read the panel and put those back on the shelf.

Blue-light filtering glasses for screen fatigue. The 2023 Cochrane review by Singh and colleagues pooled the randomized trials of blue-light filtering spectacle lenses in adults and found no clear evidence that they reduce visual fatigue from computer use, and no clear evidence for sleep or macular health either. If tinted lenses feel comfortable, wear them; just do not buy them expecting a measured effect on strain.

Eyebright. Euphrasia has a long folk history and no controlled human trials of any size for vision. It appears in "vision formulas" on reputation alone.

"Vision restoring" and "20/20" formulas. Any product whose front label implies vision will come back, or that a prescription will improve, is claiming something no trial has shown for any ingredient. The best-evidenced eye supplement in existence, the AREDS2 formula, slowed progression of one disease in one group; it did not improve anyone's acuity.

Mega-dose vitamin C for eyesight. Vitamin C was one part of the AREDS formula (500 mg), but on its own it has no evidence for vision beyond avoiding deficiency, and, as we will see, absorption falls off above roughly 400 mg in a single dose. Taking 1,000 mg or more "for the eyes" is not supported by anything.

Omega-3 for dry eye and for AMD, at least as marketed. This one is more nuanced, so it gets its own subsection below. The short version: two large, well-run trials, one for AMD and one for dry eye, both came back negative.

What has evidence, with the studied dose and the ceiling

For each ingredient here the studied dose and the safety ceiling come from our ingredient record, and every product we mention later is compared against those numbers.

Lutein and zeaxanthin

Studied dose: 10 mg lutein with 2 mg zeaxanthin daily. Ceiling: 20 mg lutein daily in long-term studies.

AREDS2, published in JAMA in 2013, was run by the National Eye Institute in more than 4,000 participants with intermediate AMD (or advanced AMD in one eye), followed for about five years. It added 10 mg lutein and 2 mg zeaxanthin, and separately 1,000 mg of DHA plus EPA, to the original AREDS formula, and also tested versions of the formula without beta-carotene and with lower zinc. The honest headline is not the one on supplement boxes. In the primary analysis, adding lutein and zeaxanthin did not further reduce progression to advanced AMD compared with the original formula. The secondary analyses, published as AREDS2 report number 3 in JAMA Ophthalmology in 2014, found that when lutein and zeaxanthin were compared directly against beta-carotene, the lutein arm did somewhat better, and that the benefit was concentrated in the participants whose diets contained the least lutein to begin with. Meanwhile, lung cancer was more common in the beta-carotene arms, mostly in former smokers. Put together, that is why lutein and zeaxanthin replaced beta-carotene in the formula: not because they outperformed it across the board, but because they were at least as good, helped the lowest-intake group, and did not carry the cancer signal.

Two things follow. First, the AREDS2 finding applies to intermediate AMD. It says nothing about healthy eyes, screen fatigue, or preventing AMD in people who do not have it. Second, the dose is 10 mg with 2 mg. Products sell 20 mg, 25 mg and 40 mg of lutein, and those numbers are above the studied amount rather than better than it. No trial has shown that 40 mg does more than 10 mg for any eye outcome. Our record's ceiling is 20 mg lutein daily in long-term studies; above that you are outside the range where long-term safety has been observed. The main documented effect of very high intake over long periods is a faint, harmless yellowing of the skin that fades once the dose stops.

What we can say more confidently is the mechanism. Supplementation raises macular pigment optical density in a dose-dependent way, which a 2016 review in Nutrients (Ma and colleagues, with Bernstein among the authors) documented across the trials. That makes lutein one of the very few supplement effects that can be measured directly in the target tissue rather than inferred from how someone feels. Smaller trials also report improvements in contrast sensitivity and glare tolerance on shorter timescales, with softer endpoints.

Form and timing: AREDS2 used free lutein; lutein esters end up roughly comparable once absorbed. FloraGLO and Lutemax 2020 are the branded extracts used in most trials. Both carotenoids are fat-soluble, so take them with a meal that contains some fat. There are no established drug interactions, but absorption competes with other carotenoids, notably beta-carotene, taken at the same time. Adverse effects were not different from placebo over five years of AREDS2.

Keep diet in mind. The AREDS2 benefit showed up in people with the lowest dietary intake. If you eat leafy greens and eggs regularly you are probably not in that group.

Omega-3 (EPA and DHA)

Studied dose: 1,000 mg combined EPA+DHA. Ceiling: 3,000 mg combined EPA+DHA without medical supervision.

DHA is a structural fat in the photoreceptor outer segments and the retina holds a lot of it, which is a good reason to think about omega-3 and the eye. It is not, unfortunately, the same as evidence that swallowing more of it changes eye outcomes, and here the two largest trials are both negative. AREDS2 itself tested 1,000 mg a day of DHA plus EPA in the same participants and found it did not reduce progression to advanced AMD. The DREAM trial, published in the New England Journal of Medicine in 2018 (Asbell and colleagues), gave about 3,000 mg a day of EPA plus DHA to people with moderate to severe dry eye for a year and found it no better than the olive-oil placebo on symptoms or on the standard signs. So the eye-specific evidence for omega-3 is weaker than the marketing, and considerably weaker than the cardiovascular evidence the ingredient record is built on.

Why keep it in the guide at all? Because most people buying eye supplements are also buying fish oil, and because the label problem in this category is worth teaching regardless. That problem is this: "1,200 mg fish oil" on the front of a bottle is not 1,200 mg of EPA plus DHA. Fish oil is a carrier; a typical 1,000 mg capsule of ordinary fish oil contains roughly 300 to 400 mg of the two fatty acids that matter, and the rest is other oil. Our record's studied dose is 1,000 mg combined EPA+DHA, meaning the number on the supplement facts panel next to EPA and DHA, added together. We will show in the label chapter how three of five popular products fall short of it once you read the panel rather than the front.

Form: the triglyceride (rTG) form is the most bioavailable, ethyl esters are the most common and absorb better with a fatty meal, and algal oil is the vegan source of DHA. Interactions: omega-3 has an additive antiplatelet effect with anticoagulants such as warfarin and the DOACs, so anyone on those should discuss it and have INR monitored where relevant; there is a modest additive blood pressure lowering effect with antihypertensives. Above 3,000 mg a day the bleeding tendency rises and the record's ceiling applies: do not go past it without medical supervision.

Vitamin C

Studied dose: 75-90 mg/day (RDA). Ceiling: 2,000 mg/day (tolerable upper intake level).

Vitamin C is in the AREDS formula at 500 mg, alongside vitamin E, zinc and copper, and that is the entire basis for its presence in eye vitamins. It was never tested on its own for AMD, and outside that combination it has no evidence for vision beyond preventing deficiency. The RDA is 75 mg a day for women and 90 mg for men, 35 mg higher for smokers, and the tolerable upper intake level is 2,000 mg a day, per the NIH Office of Dietary Supplements. Absorption falls sharply above about 400 mg in a single dose, so the 1,000 mg tablet delivers proportionally less than the 500 mg one, and the excess leaves in the urine. Splitting a dose does more than raising it.

Two cautions from the record. High intakes raise urinary oxalate, which matters to anyone who has formed calcium oxalate kidney stones, although large prospective cohorts did not find an association between vitamin C intake and stone risk at ordinary intakes in the general population. And vitamin C increases iron absorption, unhelpful in hemochromatosis. Above roughly 2,000 mg a day, diarrhea and cramping are the predictable result. If you take an AREDS2 formula you are already getting 500 mg; a separate 1,000 mg tablet "for the eyes" adds nothing the trial tested.

Coenzyme Q10

Studied dose: 100 mg/day with fat. Ceiling: 1,200 mg/day (well-tolerated in trial use).

CoQ10 shows up in eye formulas because it is a mitochondrial antioxidant and the retina is metabolically busy. That is a plausible story, and it is where the eye-specific evidence mostly stops. There are small trials of CoQ10 in glaucoma and optic nerve conditions, but they are small, and we are not going to build a recommendation on them. The evidence in the ingredient record is cardiovascular and neurological: heart failure as an adjunct at 300 mg a day in the Q-SYMBIO trial, migraine prevention, statin-associated muscle complaints with mixed results. If you take CoQ10 for one of those reasons, 100 mg a day with a fat-containing meal is the record's studied dose. If you take it specifically for your eyes, you are extrapolating.

Absorption increases three to four times with dietary fat, so timing with a meal matters more than brand. Ubiquinol (the reduced form) is preferred for older adults; younger users absorb ubiquinone well. Interactions: CoQ10 may reduce the effectiveness of warfarin, so anyone on it should monitor INR; there is mild additive blood pressure lowering with antihypertensives; people on certain chemotherapy agents should ask their oncology team. Taken late in the day it can interfere with sleep. Ceiling: 1,200 mg a day, well tolerated in trial use.

Ginkgo biloba

Studied dose: 120 mg/day of standardized extract. Ceiling: 240 mg/day.

Ginkgo is sold for "eye circulation" and, sometimes explicitly, for glaucoma. The evidence that actually exists is for a specific standardized extract, EGb 761, in people with existing cognitive impairment or dementia, at 240 mg a day over 22 to 26 weeks (Tan and colleagues, 2015 systematic review and meta-analysis). Trials in healthy adults have not reproduced those findings, and there is no established benefit for healthy eyes. If you already take ginkgo for another reason, the record's studied dose is 120 mg a day of extract standardized to 24% flavone glycosides and 6% terpene lactones, and the ceiling is 240 mg a day.

The safety point is more important than the efficacy point. Ginkgo inhibits platelet-activating factor, there are case reports of spontaneous bleeding, and it should be stopped at least two weeks before any planned surgery, including eye surgery. The bleeding risk is additive with warfarin, aspirin and clopidogrel. It may lower the seizure threshold, so caution applies in epilepsy, and it induces CYP2C19, which can lower levels of some anticonvulsants and proton pump inhibitors. A label that gives only a milligram figure for "ginkgo leaf" without the 24%/6% standardization is not selling the studied material.

Reading the label

For each ingredient we took the products people actually buy, read the supplement facts panel, and wrote down what it says. Where a product's label sentence was captured we quote it verbatim; where it was not, we say the amount was read from the listing.

Lutein and zeaxanthin: five labels

Studied dose: 10 mg lutein with 2 mg zeaxanthin daily. Ceiling: 20 mg lutein daily in long-term studies.

PreserVision AREDS 2 Eye Vitamins, 120 softgels (Bausch + Lomb), about $30.99. The panel reads 10 mg lutein and 2 mg zeaxanthin per daily dose (read from the listing). This is worth stating plainly, because it is rare in this industry: this is the formula used in the AREDS2 trial itself, at the amounts the trial dosed. When you buy it you are buying the studied product at the studied dose, and that is not something we can say about almost anything else on this site. The 130 softgel version, PreserVision AREDS 2 Eye Vitamins, 130 softgels, about $33.57, is the same 10 mg lutein and 2 mg zeaxanthin (read from the listing). Both are the full AREDS2 formula, so you also get 500 mg vitamin C, vitamin E, zinc and copper, and the trial evidence attaches to that combination in intermediate AMD, not to healthy eyes.

Lutein & Zeaxanthin, 60 softgels (NOW), about $16.79. 25 mg lutein and 5 mg zeaxanthin per softgel (read from the listing). This clears the AREDS2 dose and is the cheapest way to do it in this set, but it is above the studied amount rather than better than it, and 25 mg is over our record's 20 mg ceiling for long-term use. A 10 mg lutein-only product would match the evidence more closely.

Premium Lutigold Lutein 40 mg with Zeaxanthin, about $16.54. 40 mg lutein per serving (read from the listing). Four times the studied dose and double the record's ceiling wording. There is no trial showing 40 mg does more than 10 mg for any eye outcome; the number is a marketing number. Premium Lutigold Lutein 20 mg with Zeaxanthin, about $14.83, states 20 mg lutein (read from the listing), which sits exactly at the ceiling and twice the trial dose.

What to look for on the panel: lutein and zeaxanthin listed separately in milligrams, ideally close to 10 mg and 2 mg; "free lutein" or a branded extract such as FloraGLO or Lutemax 2020; and no beta-carotene if you smoke or have smoked. If lutein sits inside a "proprietary eye blend" with a single combined weight, you cannot tell how much you are getting; choose a different product.

Omega-3: five labels, three below the dose

Studied dose: 1,000 mg combined EPA+DHA. Ceiling: 3,000 mg combined EPA+DHA without medical supervision.

This is where the front of the bottle and the back of the bottle disagree most.

Nordic Naturals Ultimate Omega, Lemon Flavor, 90 Soft Gels, about $33.75 (about $0.75 a day). Reaches the dose: 1,200 mg per serving, and the label reads "Omega-3s per serving Potency 1200 mg".

Triple Strength Omega 3 Fish Oil 3600 mg, EPA & DHA, 120 Softgels, about $34.95 (about $0.87 a day). Reaches the dose comfortably: 2,160 mg per serving, and the label reads "1300MG EPA + 860MG DHA". Note that this is still under the 3,000 mg ceiling, but it is the one product here where doubling up would take you past it.

Nature's Bounty Fish Oil Omega 3, Supports Heart Health, 1200 mg Fish Oil, 200 Softgels, about $11.40 (about $0.17 a day). Below the dose: 360 mg per serving. The front says 1200 mg fish oil; the panel says "360 mg omega-3". That is the gap in one product: 1,200 mg of oil, of which 360 mg is the part that was studied. You would need three softgels a day to reach 1,000 mg, which changes the price per day.

Sports Research Omega-3 Fish Oil 1250mg from Wild Alaska Pollock, 90 Count, about $27.95 (about $0.31 a day). Below the dose, but close: 950 mg per serving, and the label reads "690mg EPA and 260mg DHA". A good-quality product that is 50 mg short of the record's studied dose per softgel.

NOW Foods Omega-3 180 EPA / 120 DHA, Molecularly Distilled, 200 Softgels, about $14.27 (about $0.14 a day). Below the dose: 300 mg per softgel, and the label reads "180 EPA / 120 DHA". Standard-strength fish oil, honestly labeled; you would take three or four softgels to reach 1,000 mg.

What to look for on the panel: ignore the "fish oil" figure on the front, find the EPA and DHA lines on the panel, add them, and compare with 1,000 mg. Check the serving size, because "per serving" is sometimes two softgels. Look for a form statement (triglyceride or rTG) and third-party testing such as IFOS or USP.

Vitamin C: five labels, all far above the RDA

Studied dose: 75-90 mg/day (RDA). Ceiling: 2,000 mg/day (tolerable upper intake level).

Every product we read exceeds the requirement by five to eleven times.

Nature's Bounty Vitamin C 500mg, 250 Tablets, about $14.39 (about $0.06 a day). 500 mg per tablet; label reads "Vitamin C 500mg". Matches the amount in the AREDS formula and sits close to the point where absorption efficiency starts falling.

Emergen-C Vitamin C 1000mg Immune Support Powder, Orange, 30 ct, about $12.12. 1,000 mg per packet; label reads "Vitamin C 1000mg". Nature Made Extra Strength Vitamin C 1000 mg Tablets, 100 Count, about $8.53 (about $0.09 a day). 1,000 mg; label reads "Vitamin C 1000 mg". Amazon Basics Vitamin C 1000mg, Vegan, 300 Tablets, about $14.81 (about $0.05 a day). 1,000 mg; label reads "Vitamin C 1000mg". Nutricost Vitamin C with Rose Hips 1025mg, 240 Capsules, about $17.95 (about $0.07 a day). 1,025 mg per capsule, read from the listing.

All five are within the 2,000 mg ceiling as a single daily dose. All five lose a large fraction of their content to the urine, because absorption falls above roughly 400 mg per dose. None has evidence for vision. If you have formed kidney stones, the 1,000 mg products are the ones to think twice about. If you already take an AREDS2 formula, you have 500 mg on board and do not need any of these.

CoQ10: five labels, all at the studied dose

Studied dose: 100 mg/day with fat. Ceiling: 1,200 mg/day (well-tolerated in trial use).

Qunol Ultra CoQ10 100mg, 120 Softgels, about $29.97 (about $0.25 a day), label reads "CoQ10 100mg". Puritan's Pride Coenzyme CoQ10 100mg, 240 Rapid Release Softgels, about $23.83 (about $0.10 a day), label reads "CoQ10 100mg". Qunol Mega Ubiquinol CoQ10 100mg, 100 Softgels, about $30.99 (about $0.31 a day), label reads "Ubiquinol CoQ10 100mg". Nutricost CoQ10 100mg, 120 Vegetarian Capsules, about $16.95 (about $0.14 a day), label reads "CoQ10 100mg". Jarrow QH-Absorb Ubiquinol 100mg CoQ10, 120 Softgels, about $45.88 (about $0.38 a day), label reads "Ubiquinol 100mg".

Every product states 100 mg, so the difference is form and price. The two ubiquinol products (Qunol Mega, Jarrow QH-Absorb) are the reduced form that older adults absorb better; the three ubiquinone products cost roughly half as much per day. Any of the five with a fatty meal matches the record's studied dose. Whether that dose does anything for your eyes is the question the evidence does not answer.

Ginkgo biloba: three labels, one over the ceiling

Studied dose: 120 mg/day of standardized extract. Ceiling: 240 mg/day.

Nature's Bounty Ginkgo Biloba 120mg, 100 Capsules, about $8.49 (about $0.08 a day), label reads "Ginkgo Biloba 120mg". Nutricost Ginkgo Biloba 120mg, 240 Capsules, Extra Strength, about $14.95 (about $0.06 a day), label reads "Ginkgo Biloba 120mg". Both state the studied dose. Check the fine print on the panel for the standardization: the trial material is 24% flavone glycosides and 6% terpene lactones, and if the panel does not say so you are not necessarily getting equivalent material.

DEAL SUPPLEMENT Ginkgo Biloba 500mg Per Serving, 240 Capsules, about $18.99 (about $0.16 a day), label reads "Ginkgo Biloba 500mg". That is more than double the record's 240 mg ceiling, and a 500 mg figure for ginkgo is very probably whole leaf powder rather than standardized extract: a different material from the one in the trials, in a larger amount than has been studied for safety. Higher milligrams here are not extra strength.

The protocol

Two protocols, because there are two very different readers of this guide.

If you are over 50 and an ophthalmologist has told you that you have intermediate AMD

This is the group with the evidence. Talk to your ophthalmologist first; the decision to start the AREDS2 formula depends on the grade of your AMD on a dilated exam.

1. Baseline: a dilated eye exam with your AMD grade recorded, and an Amsler grid at home (the checkered card that shows distortion in central vision) checked in each eye separately once a week.
2. Supplement: the AREDS2 formula as sold, providing 10 mg lutein with 2 mg zeaxanthin daily (ceiling: 20 mg lutein daily in long-term studies), plus its 500 mg vitamin C (ceiling: 2,000 mg/day, tolerable upper intake level), vitamin E, zinc and copper. Take it with a meal containing fat. Do not add a separate lutein product on top; you would only be moving toward the ceiling with no evidence of extra benefit.
3. Do not add: beta-carotene products if you smoke or smoked; extra vitamin C; a "vision formula" on top of the AREDS2 formula.
4. Omega-3 is optional and not for the eyes: AREDS2 found no AMD benefit from 1,000 mg EPA+DHA. If you take it for cardiovascular reasons, 1,000 mg combined EPA+DHA a day (ceiling: 3,000 mg combined EPA+DHA without medical supervision), from a product whose panel actually reads 1,000 mg or more.
5. Time frame: the AREDS trials ran for years, and the outcome is a lower rate of progression, which you cannot feel. The markers are the ones your ophthalmologist tracks at follow-up (typically every 6 to 12 months) and any change on your weekly Amsler grid, which is a reason to call, not to wait.

Everyone else: screen fatigue, tired eyes, "eye support"

Here diet and habits come first, because that is where the evidence points, and a supplement comes in only if your intake is low.

1. Baseline, week 0: an eye exam if you have not had one in two years (uncorrected or under-corrected refractive error is a common cause of "strain"), and a one-week symptom diary noting burning, grittiness, blur, headache and end-of-day fatigue, each scored 0 to 3. Also log screen hours and breaks for the same week; most people underestimate the first and overestimate the second.
2. Weeks 1 to 4, habits only: the 20-20-20 rule (every 20 minutes, look at something about 20 feet away for about 20 seconds; use a timer); deliberate full blinks when you notice dryness; screen top at or slightly below eye level, about an arm's length away; room lighting not brighter than the screen; humidify a dry room; daily time outdoors in daylight (for children, the myopia measure with the best evidence). Repeat the symptom diary at week 4. Sheppard and Wolffsohn's review is candid that the trial evidence for the 20-20-20 rule specifically is thin, but it costs nothing and addresses the actual mechanism, which is more than any capsule can say.
3. Weeks 5 to 12, add lutein and zeaxanthin only if your dietary intake is low: if you rarely eat leafy greens, eggs, corn or orange peppers, 10 mg lutein with 2 mg zeaxanthin daily (ceiling: 20 mg lutein daily in long-term studies), with a fat-containing meal. Choose a product close to that dose rather than a 40 mg one. If you eat those foods most days, skip the supplement; the AREDS2 benefit did not show in people with adequate intake.
4. Optional, not for the eyes: omega-3 at 1,000 mg combined EPA+DHA a day (ceiling: 3,000 mg combined EPA+DHA without medical supervision) if you want it for general health, from a product whose panel reads 1,000 mg or more of EPA plus DHA. Vitamin C only to meet the 75-90 mg/day RDA from food (ceiling: 2,000 mg/day, tolerable upper intake level); no separate tablet for the eyes. CoQ10 (100 mg/day with fat; ceiling 1,200 mg/day, well tolerated in trial use) and ginkgo (120 mg/day of standardized extract; ceiling 240 mg/day) only if you take them for other reasons, and ginkgo not at all if you take a blood thinner or have surgery planned.
5. Week 12 review: compare the symptom diary with week 0 and week 4. If the habit changes moved the numbers and the supplement did not move them further, you have your answer and can stop the supplement. If nothing moved and symptoms are daily, that is a reason to see an optometrist or ophthalmologist about dry eye disease or refractive error, not a reason to add another product.

Measurable markers, in order of usefulness: the dilated exam and Amsler grid (for the AMD group), the symptom diary scores, screen hours and break count, and macular pigment optical density, which some optometry practices can measure and which is the one number a lutein supplement reliably changes.

When to stop and when to see a doctor

Some symptoms are never a supplement question. Go to an eye emergency service or emergency department the same day for a sudden loss or change of vision in one or both eyes; a sudden shower of new floaters or flashes of light, especially with a shadow or curtain across part of your vision (possible retinal detachment); eye pain, particularly with redness, headache, nausea or halos around lights (possible acute glaucoma); new double vision; and straight lines that look wavy or a dark or blank patch in the center of vision (central distortion, which in someone with AMD can mean progression to the wet form).

See an ophthalmologist or optometrist promptly, though not necessarily the same day, if screen fatigue is present most days for more than a few weeks; if you notice a change in your ability to read or see at night; if you have diabetes, high blood pressure or a family history of glaucoma or AMD and have not had a dilated exam in two years; or if a child's distance vision seems to be worsening.

Stop the supplement and talk to a clinician if you take an anticoagulant or antiplatelet drug (warfarin, a DOAC, aspirin, clopidogrel): omega-3 has an additive antiplatelet effect and ginkgo carries a bleeding risk that is additive with these drugs, and CoQ10 may reduce warfarin's effect. If you have surgery planned, including cataract surgery, stop ginkgo at least two weeks before and tell the surgeon and anesthetist about every supplement you take. If you are pregnant or breastfeeding, discuss any supplement first; DHA has a role in fetal development at food-level intakes, but herbal products such as ginkgo have not been studied for safety in pregnancy. If you smoke or used to smoke, avoid any eye formula containing beta-carotene. If you have formed kidney stones, avoid high-dose vitamin C. If you have epilepsy, avoid ginkgo. If you take chemotherapy, ask your oncology team before taking vitamin C or CoQ10.

Finally, stop expecting a supplement to do what it was not studied to do. The AREDS2 formula has a specific job in a specific group. Everything else in the eye aisle is selling the halo of that trial to people it never included.