High Myopia Divergence Insufficiency Illustrated

That is near-ideal extraocular muscle placement:
Screenshot_20210112_141602


That is muscle placement below ideal, but yet within normal range and found in many healthy subjects:
Screenshot_20210112_141648


But if the angle deviates further, symptoms such as divergence insufficiency, esophoria or esotropia and/or complex strabismus like esohypotropia is present, in the latter stages the eye is stuck and even can’t move from downward and inward position:
Screenshot_20210112_141721


The last in scientific language is termed “LR-SR band thinning” or supratemporal eyeball prolapse/protrusion. Seen in high myopia and aging people, yet quite rarely in both cases. Lateral Rectus and Superior Rectus muscles are connected by band that can thin out, causing an increase in angle between placement of both muscles named; or even disrupt - in this case the angle could increase from normal near 90 ±10 to above 180.


That’s diagnosed on AS-OCT (if I not err), MRI, radiology or CT.

You can look on the first image with significantly abnormal muscle placement and the second with relatively normal:


That’s why I would consider surgery here; if it is shown on MRI or similar.
There are reversible surgeries like belly union of LR and SR, but they would be not enough if the angle of eye displacement is too big.

As I said, I don’t have restriction in movement of eye.
Sometimes just before or after sleep I have large exo(hyper)phoria, and its clear cause is inferior oblique overaction moving eyes extremely up and out - as I also have apparent overelevation in adduction. To add, I also have some degree of overdepression in adduction…

But abnormal strength development of inferior oblique might be a compensation of malfunctioning (and possibly misplaced) lateral rectus, to still move the eye up and/or out. I wonder whether overacting inferior oblique muscles could gradually move maxillary bone in thus creating malocclusion such as Class III or upper incisor deep bite. Or rather maxillary bone in creates inferior oblique overaction; but biomechanically maxillary bone inward movement should create underaction of muscle mentioned. There is definitely a link between occlusion thus cranial alignment and strabismus.

@FMR, perhaps you have some experience about resolving vergence problems. I doubt so complex, but you are also a researcher. So you might want to leave some your points of vision about…

@Dlskidmore, I guess it’s not too sensitive for you, but you also might want to describe whether you have some of eye alignment problems with such high degrees of myopia. Even if you alternate opened eye and things far away are placed differently in each eye’s image.

I wonder as well whether this type of muscle slippage will not cause non lens-induced astigmatism often found in high myopia.

Because I’ve came across the video illustrating “loop myopexy” surgery to fix this and noticed that astigmatism was only found in eye which was turning and other eye which was not turning had zero astigmatism despite the same amount of myopia.

@Varakari @FMR @Ursa

R. E. -16.50 DS
L. E. -16.50 DS -2.50 DC@ 100

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The question is, is it the muscle being loose, or the eye being turned that is causing the astigmatism?

In any case, if the surgery (which corrects both conditions listed above) causes the astigmatism to decrease over time after the procedure, we could conclude that the deformed cornea was a temporary condition.

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