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.