The key metric is pixels per degree, which is going to come from both the field of view in VR as well as the monitor resolution.
To put this in Snellen eye chart perspective, in order to read the 20/20 line and distinguish letter details to tell them apart, you have to be able to see details as fine as 1 arc min - 1/60th of a degree.
So basically if your math comes up with less than 60 pixels per degree, you are going to essentially be near sighted inside of the VR environment.
Let's say you have a set of VR goggles with a 140 degree field of view. You need 140 degrees * 60 pixels/degree =8400 pixels to get that same visual acuity as 20/20 vision in real life.
Using HP's new G2 goggles (coming out soon) as an example, they have a screen resolution of 2,160 pixels,and (I've read) about a 100 degree horizontal FOV. That works out to about 22 pixels per degree. Which is about like having 20/55 vision. This is why in VR, you can't read things from a normal distance if drawn to scale. You have to either get closer to them (in VR) or scale them up to make them readable.
You CAN give the user effectively better vision by reducing the field of view. If you don't mind having a 36 degree wide field of view, you'll have 20/20 vision.
To put this in Snellen eye chart perspective, in order to read the 20/20 line and distinguish letter details to tell them apart, you have to be able to see details as fine as 1 arc min - 1/60th of a degree.
So basically if your math comes up with less than 60 pixels per degree, you are going to essentially be near sighted inside of the VR environment.
Let's say you have a set of VR goggles with a 140 degree field of view. You need 140 degrees * 60 pixels/degree =8400 pixels to get that same visual acuity as 20/20 vision in real life.
Using HP's new G2 goggles (coming out soon) as an example, they have a screen resolution of 2,160 pixels,and (I've read) about a 100 degree horizontal FOV. That works out to about 22 pixels per degree. Which is about like having 20/55 vision. This is why in VR, you can't read things from a normal distance if drawn to scale. You have to either get closer to them (in VR) or scale them up to make them readable.
You CAN give the user effectively better vision by reducing the field of view. If you don't mind having a 36 degree wide field of view, you'll have 20/20 vision.