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ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia

Effect of (differential) LASIK on binocular use (1 Viewer)

Kiwimac

Active member
A couple of years ago, I had differential LASIK. This means that my left eye is sharply focussed at reading distance and my right at far viewing distance.

IRL this essentially gives me at 53 the same vision I had at 16 - I can see everything clearly (if I use both eyes!) from near to far. This is because the brain soon learns to meld the two images into one.

So far, so good.

With binoculars, I can use the diopter correction to adjust so that both eyes see equally. My question is...do they?

Using my NL 12x42 as an example:

1) When panning, my eyes seem to focus on what could be an internal reflection which looks like a ghostly and faint irregular pattern, like something seen vaguely in a mirror. It goes away when the image is not moving. I see it too in my EL 8.5x42.

2) In the NL, with the eyecups fully out, the edge circle around the view is slightly fuzzy. Wound one click in, it seems more sharp. However see (3) below

3) I sometimes get a vague impression that the centre of the image is 'not quite right' as if IPD is not correct - but AFAICT it is; this is a very vague suggestion of slight 'oddity' in the view - very hard to describe

The binoculars are new and I do not think that they are faulty (at least not in any obvious way I can see) so I am wondering whether it is just a set of slight imperfections possibly arising from the LASIK which is causing this.

I have not found much information on the possible effect of corrective eye surgery on binocular use, but I am sure I am not the only person to have had such surgery and used binoculars!

It does all seem more noticeable when panning and moving the view. If you sit still and simply allow the eye to relax into the gorgeous NL view, it's invisible.

I'd be interested in any thoughts anyone has on the subject.
 

PeterPS

MEMBER
I don't think your monovision is the problem. The view thru the NL binos is rather sensitive to eye placement. When panning your eyes are not always perfectly centered with the EPs and then the view thru the binos can be affected by blackouts and glare (the latter being caused by internal reflections which exist in both the ELs and especially NLs)---to avoid these rather unpleasant effects, the only solution is a perfect allignment between your eyes and the binos (both the IPD and the height of the eycups should be finely tuned).
 

Kiwimac

Active member
Ok. Good to hear. The ideal eyecup position seems to be mid way between fully extended and the first stop below that. Of course there's no way to make them stay at that point!

I have noticed that eye placement is quite critical. One time you can put them to your eye and the view seems spot on. Next time you're wondering what's not right and fiddling.

The forehead rest was the suggestion of Swarovski to help and it does do that to be fair.

It would be easier to set up if IPD was adjusted in the same way as focus - with a wheel - rather than the less precise 'move it with your hands' system.
 

tenex

reality-based
The forehead rest was the suggestion of Swarovski to help and it does do that to be fair.
One could suspect that the FHR was actually introduced to help maintain critical eye placement with the NL, rather than to improve stability.
 
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ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia

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