Do you need a test lens kit? How to decide

After a year of owning one and seeing quite a few questions on this topic, I thought I’d summarise my findings and thoughts. Yes I know the bearded one has a video on this but these are just my thoughts and I prefer text…

So, do you need a test lens kit? This question is also preference related so rather I’ll try to answer the more easily answered question of how useful is it in which scenario…

  • If you just have low myopia and no cylinder : not really useful
  • If you have high myopia and no cylinder : Probably not useful
  • if you have very high myopia you have to be careful with the vertex distance accuracy - a test lens frame might put the lens far from the eye causing you to think the lens is too weak. Alternatively, holding a lens to the eye too close can also make you think a weaker lens is good enough: so a kit is less useful if you have very high myopia
  • If you have a complex prescription involving sph and cyl : useful
  • as above plus big difference between the eyes: even more useful
  • you plan to just make one big initial reduction then 0.25 D steps down from there: not useful
  • you plan to sometimes experiment with more complex steps like trading 0.5 D cyl for 0.25.sph OR experimental steps like dropping cyl altogether : useful
  • you have high myopia and some cyl and want to have e.g. 3 sets of glasses, norms, diffs and one for extra close up like smartphone : quite useful

Summary: the more complex your prescription and the more alternative lens reduction paths you want to try, the more useful it is up till moderately high myopia. At very high myopia, the vertex distance accuracy with the test lenses can become an issue, reducing usefulness. The more simple your path the less useful a test lens kit is.

Weigh up your reduction path complexity vs test lens kit price.

Me personally? I used it a lot at the start and since then only when doing a lens change OTHER than dropping 0.25 D.

Just keep in mind that a wrong lens can cause strain or headache hours or days after starting use so may not be evident when trying that prescription with the test kit.

And don’t try too many lens combinations in one session.

Hope this helps someone.

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Yes haha I was going to say a test lens kit would have set you back only around 180 Eur

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Very high myopia, vertex distance is a bear, and lenses you buy over the internet will have unknown vertex distances. High end of the test kit was not helpful. My astigmatism is minor, and is ghosting rather than directional blur, which can’t be fully corrected by cylinder anyway.

Portions of my kit I have used more:

  • -2 to +2 lenses - you could just get flippers for these rather than a full kit. Just 0.25 and 0.5 flippers are all you need to make small adjustments to your wearing lenses.
  • stenopaeic slit - super easy to confirm astigmatism angle has not changed, but this bit of kit is easy to make from cardboard if you’re not trying to fit it into a trial frame.
  • opaque or diffusion lens, to keep the lens I’m not testing honest, could easily use a patch instead.

your myopia is very high, but it seems your prescription is not complex, right?

so your conclusions match mine in that you could have done without the kit, right?

plus for you the extra gravity of the vertex distance accuracy makes it even more difficult to use a test lens kit as you will get the wrong impression if the lens is too far from or close to the eye.

I will add this to the summary

Pretty much.

My husband’s prescription is more complex, and I think we will get a little more benefit from the test kit with him. I can do a complete refraction for him without too much concern over vertex distance woes. But mostly the cylinder measures were straight off of the prescription, we didn’t experiment with that besides seeing how dropping some of it felt.

For sure having another person who uses it in the house is another point in the pro test lens kit column :grin:

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Theoretically it should be possible to share a test lens kit if several people lives in the same area. Of course it’s a bit hard to organize it and find the people but once it settled it can be beneficial. FB group should be a good place to try to do something like that.

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My trial frame was mailed to me by another member who no longer needed it. If I stop using the kit after a few reductions I might be able to pass it on.

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