“6/6” is the way visual acuity is written in countries that measure in metres, including India, the United Kingdom and Australia. It describes how clearly you see at a distance compared with a reference standard.
Reading the fraction
The first number is the testing distance — 6 metres. The second number is the distance at which a person with standard vision could read the same line. 6/6 means you can read at 6 metres what a person with standard vision reads at 6 metres. 6/12 means you need to be at 6 metres to read what a person with standard vision can read from 12 metres away — so your distance vision is less sharp.
Is 6/6 “perfect” vision?
No. 6/6 is a reference point for normal distance acuity. Many people see better than 6/6 (for example 6/5). Acuity also says nothing about colour vision, visual fields, depth perception or eye health.
Corrected and uncorrected vision
- Uncorrected (unaided): measured without glasses or contact lenses.
- Corrected (aided): measured while wearing your glasses or lenses.
Seafarer eyesight standards specify minimum acuity for each eye and both eyes, and may set different minimums for aided and unaided vision depending on duties. Those values are set in STCW Table A-I/9 and by your national authority — your examiner applies them.
Decimal notation
Some forms use decimals: 6/6 equals 1.0, 6/12 equals 0.5, and 6/60 equals 0.1. You may see the same result written different ways.
Frequently asked questions
Is 6/6 the same as 20/20?
Yes. 6/6 is the metric form; 20/20 is the same acuity measured in feet.
Is 6/6 required for seafarers?
Requirements are set in STCW Table A-I/9 and national rules and differ by duty and between aided and unaided vision. Ask your examiner which standard applies to you.
Sources
- World Health Organization — Blindness and vision impairment — fact sheet (opens in a new tab)
- International Maritime Organization — STCW Convention and Code — Regulation I/9, Section A-I/9 (opens in a new tab)
Links go to the original publishers. SeafarerFit is not affiliated with or endorsed by these organizations.
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