I have monocular sometimes but think it is not caused by MG.

When I am really tired or have been out in the sunlight for a while, I get monocular double vision in my left eye, the one that also has more ptosis and that is the main culprit in my binocular double vision. My ophthalmologist doesn't think that could be an MG issue and told me it is more likely a dry eye problem. But, I really wonder whether it is an MG thing, since it seems to be related to fatigue. I think the relationship to bright sunlight is because I squint in bright light, which might fatigue my eye muscles. The monocular double vision manifests itself as "ghosting", for example a second fainter image of a line of print when I am reading. My ability to focus my left eye also is worse when I am tired. Resting my eyes (I love my naps!) resolves both my monocular and binocular double vision, and my issues with focusing. The vision in my right eye is pretty stable and doesn't change much at all with my fatigue level. By the way, my ophthalmologist is the one who ordered blood tests for both thyroid disease and MG, although I am seronegative for MG. I also have Hashimoto's.

I hope your Mayo visit goes well!
Pat

My ophthalmologist told me that monocular double vision is nearly always dry eye related. Systane eye drops are awesome for dry eyes! They are specially lubricated to last a long time and really protect you. I used them for a long time.

I have monocular double vision in both eyes which is multiple ghost images stacked above each other. There is a daily pattern of better in the morning getting really bad in the evening. But on top of that every day is different. One eye, two eyes, sometimes ok sometimes terrible etc. Tru I have dry eyes but there is little correlation between the two. Eye drops make the dryness more comfortable for a time but doesn't fix the DV. I have had loads of blood tests over the years and questions about MG but no proof. Bit fed up with optician specialist as they never seem to listen to a word you say.
I have found your brain is quite clever though as it now more or less ignores the effect on most day to day activity. It only really catches you out when you really need to read a number and find it impossible to distinguish 3,6,8 &9's as they all mush into a series of interlinking circles.
If reading in the evenings ends up being impossible try doing computer work in the morning. Try out audio books too which I have really got into. Duncan

I have no Pstosis but have had longstanding an very 'peculiar' large right hypertropia worse in right upper gaze.It has a high phonic component I also have an elevation failure in my left eye. My OPHT feels it isn't MG even though I test positive for antibody?
He feels it could be a longstanding 'Brown' syndrome?
Since my readings are highly variable (which I attribute to MG)..he has doesn't presently have an treatment for my double vision and ghosting..etc