First of all, my apologies because this opening post has turned up being too long…
It has been a while since I’ve registered here at the EM forum (ca. November 19) and for different reasons, I sort of left all the EM journey behind and couldn’t start with it. The thing is that now in the present, after I decided to take this seriously and finally start with it, sadly I couldn’t reach a point in which I’m sure about how to proceed. It must be a mixture between analysis paralysis and high myopia related issues that mild myopia users may not experience.
At the moment this is my prescription:
R: -7.25 -1.00 CYL 143º // Contact lens -6.50 CYL -0.75 140º (biofinity toric from cooper vision)
L: -8.00 -0.25 CYL 20º // Contact lens -7.50 (biofinity from cooper vision)
And these are the 5 annoying things that stop me:
1) HOW TO ACCURATE MEASURE THE DISTANCE TO BLUR:
As it would be both, kind of tricky and hardcore to measure right from the surface of the open eye, I think I’m not doing it accurate enough and I’m very frustrated as 2-3mm difference can be translated into a -0.25…
I do have one of these lasers measuring tools from Bosch (Zamo) and it seems a pretty cool toy to be used for this, but the minimum operating distance must be >15cm and currently I can’t go beyond 13-14cm In the EM guides was mentioned one DIY tool involving a flexometer and some mini snellen chart or similar thing attached to it.
This seems to be the easiest way to track the progress until I can get longer distances, but I don’t know what should I use in the chart. I came up with this humble creation:
According to the size I should pay attention to, I will get one or another amount of cm. Which font size should I pick? (For instance, MS word or notepad uses 11 size by default). Is this a matter about losing the sharpness of the overall and not from one size in particular? Any advice about it? And also very important too! Any suggestion about how to hold this mini chart tight in the flexometer? I Couldn’t figured out yet how to build a frame or bracket mount for it.
2) CHOOSING THE RIGHT DIFFERENTIALS
Sadly I spend a lot of hours in front of the computer or close up distances (lockdown and other restrictions with lack of outdoor life + PC or books + the office)… I do really want to get nice refreshing differentials to relief some strain in my poor mistreated eyes, but first I really need the confirmation of the process. Is this sketch right?
After wearing the first differentials for a while, it’s time to get the first normalized and its corresponding differentials, take the time to get use to it and repeat until succeed… Or on the other hand, one would wait for the second differentials until the eyes get used to the first normalized?
Going further, as I do have a trial kit, I have measured these approximate readings:
PC USAGE (80-95 cm to screen):
• If I overlap one +0.50 lens to my full glasses lens seems like nothing happens. Starts getting blurry at +0.75, and with +1.00 it’s perhaps too blurry. I still can read the text, but it takes a bit of effort and not sure if AF will work to this degree. +1.25 it’s clearly too much and out of range.
• With my trial frame if I get rid of the astigmatism and use only myopia lenses, I think I could go for -7.75 L and -7.50 R, but it seems perhaps blurry enough to make the AF very hard or even impossible.
BOOK USAGE (distance to book ca. 45 cm):
• If I overlap one +2.00 lens to my full glasses lens it’s a bit blurry, but I can read quite easily. +1.75 it’s even more comfortable, +2.25 feasible though in the limit. +2.5 is too much.
• With my trial frame if I get rid of the astigmatism and use only myopia lenses, I think I could go for -6.00 L and -5.50 R
And here comes the question: The forbidden advice about which prescription should I go for!
Would be better to keep the -1.00 CYL for the right eye or reduce it by just a quarter for both eyes? (meaning, -0.75 R CYL and 0.00 L CYL). Maybe better just go directly to myopia only and discard all the CYL values? (In my opinion, there is a huge difference in terms of blur with and without CYL, so better keep it with a quarter or a maximum of a half less?). Could you please also give me one visual example about the limit of “too much blur, rather be conservative” to work with to enable an easier AF and prevent blur adaptation and double vision? And what should be the strategy to tackle the astigmatism and get rid of it? Reduce by a quarter each alternating cycle of normalized/differentials?
About getting the glasses… for the PC I do need the 1.74 Index as otherwise it will end up pretty heavy and uncomfortable in the nose, plus it creates a big distortion in the face. I am aware about the ABBE index, but I’m not so sure about which kind of materials should I expect to be offered to choose from within this index, or if there is none to be chosen as there is only one (needless to say, I don’t want distortions, chromatic aberrations and other undesired things). For the reading ones maybe will be enough with 1.67 index. Is there any tool or formula to get the resulting mm of the lens according to the diopters and the index?
The fear of ordering a wrong pair of glasses causes me some anxiety, as the last ones I’ve order (and the reason to register here in November 2019) were exactly 598€ and they were never worn, never used. More than half thousand euros directly sent into the trash can, as the optician refused to change the lenses because otherwise “it will be under my real prescription”. This time I would order them to the EU/Spanish Zenni equivalent (SmartBuyGlasses), which should cut the expenses by a half at least, but wasting 150-200€ per glasses doesn’t sound good to me either. I really need to nail the prescription, or be very close to it…
3) MEASURING THE PUPILARY DISTANCE
Another tricky thing before ordering any glasses is the PD measurement. As before, it seems that it is important to be accurate with high myopia and perhaps it’s better to measure eye by eye instead doing it for both at the same time (comments about this?). I’ve seen suggested in the Discord server the “Glass on” app for Android, but even in the promotional video for this app on YouTube they also say that with high myopia it’s important to be accurate and perhaps better to measure eye by eye,
Because I have one of these trial frames, not sure if I can profit from it and use it to measure this PD. The numbers from 25-40 mm right above the eye do measure it, right?
Will that work or do I need to try something else? For a long distance the 598€ optometrist wrote a PD of 31.5 mm R and 30 mm L, though not sure how much could this vary to mid and close distance. Sadly, the cooperation of a friendly optometrist does not seem to be possible and I’m on my own… At least at the moment
4) MEASURING THE VERTEX DISTANCE
If the PD and the right prescription wasn’t tricky enough I think I also need to take in consideration the vertex distance. As I said before, a difference of 2-3mm could result in -0.25 diopters in this high myopia league, up to -0.5 if the mm doubles. It seems that (according to the formulas), one can finally forget about all of this stuff in the range of -2.25 or -2.5 as the variation is minimal or directly non existent, but I’m around -5 diopters ahead of it.
Is there any accurate way to know which vertex distance I am actually using in my current glasses? Do you know where could I get a cheap distometer? (such as this one for instance). For those simple as a transparent rule I require a second person I don’t have
Is there any way of assuring an identical or a very similar vertex distance between the glasses ordered online and the ones I’m wearing? As said before, I’m afraid of ordering the right amount of diopters per eye, but due to the incorrect or unknown vertex missing or adding some strength to the lens. Does this distance can eventually be adjusted in an optic?
Lastly I have dumped the vertex formula into an excel sheet and played with it a lot already, but any advice regarding how should I proceed with the contact lenses? Should I base their power in the normalized or in the full strength glasses? I’m afraid of getting good results, but then ruining them when wearing the contact lenses because they may be overprescribed.
5) CONTACT LENSES
I do use contact lenses too. Years ago I’ve stopped using them for work or close up reading, as it caused me a lot of pseudomyopia and dry eye. Now I only use them when I’m travelling, practicing sports, or in any kind of outdoor activity that either requires high precision or makes the experience more enjoyable/safe. Yet… I also have problems with the contact lenses sigh (-_-). The issue is related with both, preserving the parity of their prescription with the glasses (either full prescription / normalized) and the power to be chosen and used in the contact lenses.
It seems that nearly all manufacturers do not work with quarters above -6.00 diopters, but only halves, and theoretically I should use -6.25 for the right eye and -7.50 for the left one. As this -6.25 doesn’t exist, I was suggested back then to use -6.50 and I’ve been using it since 2017 or 2018. This has created a big imbalance between the right and left eye, as with contact lenses my right eye is more dominant than before and does all the work, while the left eye seems to be asking for more power as I can’t see as sharp as with the right one. That was later experienced with the glasses too, and I would say that even today I can see a tiny bit better with the right eye when I wear them. I was then suggested to increase a quarter in the contact lens for the left Eye to fix it, but because this -7.75 does not exist, I should jump directly to -8.00. That was rejected by me in less than a week of trial as it was leaving behind the right eye capabilities and it was asking for more power (another non existing quarter, translating into -7.00!). This would also made my current 615€ glasses obsolete as I will need even stronger ones, and so it would continue the never ending story until reaching -50 diopters or who knows what. Conclusion: I really REALLY need to be careful with the contact lenses strength and match them as accurate as possible with the prescription of my full powered glasses and/or the normalized ones if I want to hold tight the myopia or thinking about reducing it. Besides thinking in an eventual future reduction, I checked this with an optometrist in the past month and it seems that both eyes work fine with -7.5 and -6.25. If I reduce the right eye, the left eye sort of activates itself and I find it better.
After hours of research I think I could answer myself the question of which brand works with quarters beyond -6.00: Air Optix plus HydraGlyde for myopia, Proclear toric for astigmatism. Those proclear have less air permeability than the biofinity, but I guess that the sacrifice of breathability could be assumed until I reach -6.00 and switch back to biofinity.
If you were able to go until the end of this post, my most sincere gratitude to you, and even more if you can help this desperate moleman
PS: I’m Leo in the Discord server. If texting here would be longer than my post, voicechatting or just chatting in Discord is more than welcome!