Prescription Glasses and VR

I am short sighted and use prescription glasses for reading, a different set for medium distance (PC work) and my long sight is OK, not requiring any glasses.

I am confused by what is best for VR.

With my Vive Pro and Index, I get best results with my 'medium' distance glasses, but when I had the Reverb, the best results were with no glasses at all.

Now, I want to order lenses for my Index from someone like VROptician, and am wondering what to use as the prescription on their site.

Do I use the one from my optician, or do I go back to them and say I would like a prescription specifically for VR headsets.

Any advice appreciated.

I did this recently, and fairly cheap also. The image quality is much better than wearing my glasses since there is no alignment issue and everything is in perfect focus with this method (my glasses don't fit well inside the facial gasket). I used a regular lens prescription from my OD. You don't have to be strict with the IPD when placing an order since with the Index you can manually change it with the slider. The insertion goes in and out easily and is super easy to install.

https://www.thingiverse.com/thing:3753906

Just follow the instructions on that web page. Their lens insertion is large and fits the Index perfectly, accommodating extra large lens. Note that the lens must be ordered from Zenni and for that particular glass frame only.

You can go more expensive route but for less than $50 including everything, it's a no brainer and a safe choice.

Thanks a lot for that info, but my question is really about different levels of vision and experience of focus in different headsets.

Any advice on that appreciated.

Thanks a lot for that info, but my question is really about different levels of vision and experience of focus in different headsets.

Any advice on that appreciated.

For me is glasses for looking on distance. Same say on the instruction for that VR optics.

As you don't need glasses for distance and you say for your Index best experiences with that midrange lenses than you just have sent them exact specs for that glasses your optician prescribe to you.

This will replicate exact experience you got with your Index and your glasses only it will be with that additional lenses.

Maybe before you should test it a little bit more before, just to be sure. :thumbup:

I don’t know about Reverb since I don’t have it, but for Vive Pro/Index go with regular prescriptions. I have split vision, as well as astigmatism and the prescriptions for my eye glasses work perfectly with the custom lens. I’d say it works better than my current contacts for prolonged use since my eyes don’t get dried. The only negative is that you’d lose a bit of FOV on the Index since then screens need to be moved away a bit more.

I’m also trying bifocal contacts soon, not sure if it’ll work any better.

Interesting. It must depend on the face shape and glasses frame as I can have the Index at full FOV with my glasses on.

I got mine from WidmoVR and just used the distance part of my prescription. Before I got the lenses I wouldn’t wear my glasses under the HMD because the glasses would contact the HMD lenses. This always ends up with both becoming scratched up. That’s a $1700 hit I wasn’t willing to take.

You need distance prescription lenses for VR, nothing else.

I use 1.75 reading glasses and I Do Not need them with the Reverb but Do need them when using my monitor.

You need distance prescription lenses for VR, nothing else.

Not sure this is true Neil, certainly in my case. If you read my posts, I don't need any prescription for distance, yet my medium distance glasses give a much clearer image in my Vive Pro and Index. However, the Reverb was better without just the naked eye.

This is one of the points I am trying to understand!

interesting question, I used distance only on my cv1 but on the Rift S, my full progressive works better than both my distance only or my 30 inch computer desk glasses.

I have split vision, as well as astigmatism

I don't know about split vision but I've got mild astigmatism in one eye.

I don't even have a VR headset (one day I'd like to).

I just base my opinions on logic here; if, according to your experience, something I say is not right, please tell me and I'll have learnt something.

Being astigmatic means that, instead of having a single focal point per eye, we have two or more. Therefore, I think that if someone has astigmatism, he'll never be able to focus properly regardless of the settings of a possible focuser, unless he uses spcific lenses for that. The reason is that without an asymmetrical lens which merges all the focal points into a single one, even if you put one of the focal points on the retina with a focuser, the other points will not be there.

If someone is nearsighted and/or farsighted but not astigmatic, this person should be able to put things on focus by using a focuser, provided the focuser has enough stroke available. The same principle holds good for telescopes (I have one and I can confirm) and, I guess, microscopes.

Thinking about this a bit more, I can't fully understand this whole thing. I mean, if we were sitting in a real life cockpit, someone with long sight could see the terrain well, but not the cockpit guages, and someone with short sight would be the opposite as the eyes are focussing on objects at different physical distances from them.

However, in a virtual cockpit, we are focussing on lenses that - although displaying objects at different virtual distances - are within millimetres of our eyes.

So, either we are focussing on one plane - the lenses - or different virtual distances. In the first case, one would think it would be the near sight ability to focus, and in the case of the latter, I don't know how anyone without perfect vision can focus on near as well as far objuects in the virtual world.

Confused!

You don't "focus" in the usual sense in VR as all objects are at infinity, this is thanks to how the fresnel lenses work. Fresnel lenses redirect the light so it is traveling parallel to each other, similar to how light would be that was hitting the eye from far away.

Now that doesn't mean that your eyes don't have to adjust their convergence distance to account for objects are closer or further away from the virtual camera - to line up each image so your brain can work out how far away said object is. This still happens inside VR goggles.

But your eyes don't have to change the shape of their lens to focus at different distances as you would in real life, this is because the distance to the actual screen does not change, regardless of whats being shown.

You can show this quite easily by closing one eye and putting your face up close to an object in VR, like a canopy frame for instance. Notice that no matter how close the object gets to your "virtual eye" its still perfectly sharp and doesn't get blurry like it would IRL. This is because the light of that image is still coming from infinity, even if the angular position of the object compared to both eyes would make it seem like its only and inch away from your face.

This happens:

This doesn't:

Fresnel Lens:

Thus Endeth The Lecture. ;):lol:

Ok, so I understand that in VR our crystilline lenses don't change their shapes because the display in the headset is always at the same distance.

I don't understand why the convergence movement happens since, as already written, the display is at a steady distance, but I guess that it's what gives us a stereoscopic view in VR. Maybe this is accomplished thanks to the fact that there is one image per eye and so the headset can somehow trick our brain.

After having read about Fresnel lenses applied to VR, I Googled it and found out that they are used in lieu of usual lenses in some headsets becuase they are lighter. So basically, as far as I've understood, all the headsets, including the cheap ones where you utilize a smartphone as a display, have a display which is way too close to the eyes to be on focus and that's why there are lenses: they let us focus even at those very short distances.

This all sounds perfecty reasonable guys, but I still can't square this against my personal experience.

As I explained earlier, I am long sighted and I don't need any corrective glasses for distance sight. I do have 2 sets of prescription glasses, one for reading and one for PC monitor use.

When using my Vive Pro or Index, I get much better image clarity by using my 'medium' distance glasses than I do with the naked eye.

However, when I had a Reverb, I had better image clarity with the naked eye.

How can we explain this?

IMHO this difference you have experienced could be caused by a difference in the focal lengths of the lenses in the headsets. Maybe the Reverb puts the image so far that you don't need glasses, whereas the other two put the image at your "medium distance".

IMHO this difference you have experienced could be caused by a difference in the focal lengths of the lenses in the headsets. Maybe the Reverb puts the image so far that you don't need glasses, whereas the other two put the image at your "medium distance".

Hmm, again, that seems reasonable, but is that not likely to cause a lot of confusion amongst users who might be moaning about the clarity of the image not realising that the focal length was different between their new headset and their old one?

If they really have different focal lengths, that may be for a number of reasons.

Probaby manifacturers take into account factors like the dimension of the display and its distance from the lenses and choose the length they think is more suitable for the rest of the design. limiting their choice only by making sure that a person without sighting problems must be able to focus properly with those lenses. They probably expect people with sight issues to do something to deal with that, like wearing spectacles or contact lenses.

So, sure, the person with perfect vision will not be affected as they can see a clear image regardless of the focal length. But, my point is that the person with imperfect vision - and a very large percentage of the population is inlcuded there - will be unaware that there is a difference between one headset brand and another, i.e. they should wear glasses with one but not the other. This could make an assessment of clarity questionable .

If you have a Rift S you can wear glasses with the HMD just fine. It is WAYYYYYYY better than the CV1. I have fairly thick framed glasses ....because I'm modern and edgy......and they fit very easily.

Hmm, again, that seems reasonable, but is that not likely to cause a lot of confusion amongst users who might be moaning about the clarity of the image not realising that the focal length was different between their new headset and their old one?

It really is dependent on what the HMD focal distance is. Unfortunately, it's a hard piece of information to gather. I don't know why it's not prominently displayed in the spec sheets.

So, sure, the person with perfect vision will not be affected as they can see a clear image regardless of the focal length. But, my point is that the person with imperfect vision - and a very large percentage of the population is inlcuded there - will be unaware that there is a difference between one headset brand and another, i.e. they should wear glasses with one but not the other. This could make an assessment of clarity questionable .

This is correct. Every HMD has a different "apparent" focal distance depending on the distance to the screen, and how the lens "alters" that distance.

The guy that said always use distance prescriptions for VR is in error. I don't use it! For a lot of people, and a lot of HMDs that's OK, but not always.

So when getting a prescription lens for a new headset. you have to do 1 of 2 things. See if the manufacturer will tell you the "apparent" focal distance, Or use a drawer full of glasses with different "powers" until you get a match.

I just went through this. I have a + distance prescription, so was able to buy 10 pairs of reading glasses at the dollar store for a buck each. I tried each one incriminating at .25 + each time until I got an exact hit. I then used this number to buy better Zenni lenes for 3D printed frames.

BTW. I'm older and can not change focus well so I need a different prescription for every few feet of change until well away from me. In other words, My prescription thats good at 10' doesn't do as good at 30', or 5'!

I don't understand why the convergence movement happens since, as already written, the display is at a steady distance, but I guess that it's what gives us a stereoscopic view in VR.

When it comes to convergence the distance to the display is meaningless. It’s purely due to the angle difference to the object from each eye.

Say that something is 8 inches away from your face directly in from of you. For your left eye, that object is slightly to the right of centre. For your right eye it’s slightly to the left of centre. This is exactly how depth is presented in VR. The different positions of objects for each eye. Each screen in a VR goggle is showing you the view from a different “virtual eye” so replicates the conversion amount that would be expected.