Editorial standards
How we research, how we grade evidence, and how we keep money away from both.
Where our information comes from
We start from the strongest evidence available and work down. In order of preference: systematic reviews and meta-analyses, such as Cochrane reviews; large randomized controlled trials; regulatory documents such as FDA approvals; expert consensus reports such as the Tear Film & Ocular Surface Society’s DEWS reports; smaller trials and observational studies; and finally expert opinion. Company press releases are used for dates and basic facts, never as proof that something works.
Every factual claim that isn’t common knowledge links to its source, and every guide lists its sources at the end.
How we grade evidence
| Grade | What it means |
|---|---|
| Strong evidence | Consistent benefit in several well-designed randomized trials, or a large trial program that led to regulatory approval for this specific use. |
| Good evidence | At least one solid randomized trial or regulatory approval, supported by other studies. Helps many people, though not everyone. |
| Mixed evidence | Small, short or conflicting studies. May help some people. Low-risk options can still be worth trying. |
| Weak evidence | Good-quality studies found little or no benefit for this use. |
| Not recommended | Doesn’t treat the problem and can cause harm with regular use. |
A grade describes the strength of the research for a specific use, not whether a product is safe or whether it will work for you. We review grades whenever significant new evidence is published and record the date of the last update on each page.
Independence
Symvana earns money from affiliate links, partner clinics and newsletter sponsorships. Commercial partners never see content before it’s published, can’t request changes, and can’t buy a grade, a recommendation or a place in a guide. Product picks are made before we check whether an affiliate program exists. Details are in our disclosure.
Medical review
Our guides are written by the Symvana editorial team from primary sources. We’re building a panel of licensed optometrists and ophthalmologists to review them. When a guide has been clinically reviewed, it will show the reviewer’s name, credentials and the review date. We won’t label anything as medically reviewed until it has been.
Our tools
Our interactive tools are educational estimates, not medical tests. We explain how each one works on its page, including its limits. The Dry Eye Profile is our own model based on published risk factors and is not a validated clinical questionnaire. The Blink Test uses an open-source face tracker that runs entirely on your device.
Corrections
If we get something wrong, we fix it quickly and note significant corrections at the end of the page. Spotted an error? Email hello@symvana.com with the page and the source you think we should consider.
Not medical advice
Symvana is for education. It doesn’t diagnose or treat any condition and doesn’t replace an examination by a qualified eye care professional.