Journal
Notes from the consulting room — what a test measures, what a number means, and which of the things you can be sold are worth the money.
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· Explained
What 6/6 actually means, and why 20/20 is the same number
A Snellen fraction is a comparison, not a score. Here is what the two numbers are, why the chart steps the way it does, and what it does not tell you.
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· In the room
The cheapest instrument in the room
A black disc with a hole in it costs less than a pound and decides whether the next thing you need is a lens or a referral.
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· Buying
Which varifocal upgrades are worth paying for
Corridor length, index and coatings are real. 'Digital', 'HD' and most brand tiers are not. What actually changes what you see.