One eye substantially weaker.

RockOrBog

Hi I hope this post is allowed as I neither need nor am I soliciting medical advice.

I recently had steel shards successfully removed from the white of my eye in an emergency eye clinic. (Amazing people) While I was there the doctor instructed me to look through this plastic thing with a hole in it and read the screen with the letters in ever decreasing size.

My left eye was perfect I could read all the way to the bottom.

My right eye has always been weaker, so I could only get around two thirds of the way around the list.

Then she flipped down a 'cover' over the eyehole. This cover had a number of small holes in it and when I looked through again with the weak eye I could read almost to the bottom. What was this witchcraft ??

Also I'm fairly sure I have perfect vision when using both eyes even though one is weaker, I don't understand that either.

realdanbreen

Did you ask her about it?

RockOrBog

https://www.boards.ie/discussion/comment/122719757#Comment_122719757

No it was an emergency eye place I didn't like delaying her as other people were waiting. Also if I asked her I'd hardly be asking here.

realdanbreen

Yeah I guess it made more sense to throw it up here than to ask the doctor in the eye clinic.

Esel

https://www.boards.ie/discussion/2058374368/one-eye-substantially-weaker

The cover with the holes corrects any vision defect in the eye by directing discrete points of light at the eye. The improvement in vision you felt indicates you should get an eye test (if the weakness is bothering you).

IANAO

cython

I suspect the science behind this is similar to how squinting can compensate for myopia/shortsightedness, by reducing the amount of light entering the eye.

The below depicts the typical description of myopia, where the lens of the eye focuses the rays of light short of the retina, and this is corrected by a concave lens, which fans the rays out before they hit the lens to lengthen the effective focal length.

However, if you imagine a squinted eye, or indeed the cover described, or peering through a pinhole, this can block the rays that are furthest from the centre of the lens. These rays are the ones generally "most" responsible for the distortion associated with myopia, as any ray passing through the centre of the eye's lens just keeps going straight, with those nearer the edge requiring increasingly more refraction to be focused. In saying that, our eyes are adapted to function best with normal light levels, so refractive correction that maintains that is by far the better remedy than a pinhole or squinting in the long term. 🙂

So to the OP, would that fit with your experience?

RiseToMe

https://www.boards.ie/discussion/comment/122720527#Comment_122720527

This is exactly it is - the pinhole effect.

The rationale of it being that, on a basic level, the level of improvement seen with pinhole should be replicable with spectacles. Had the pinhole offered no improvement to your level of vision, it would indicate a possible pathological cause/result of injury in your case that means the use of spectacles for correction is limited.