Fourth nerve palsy and double vision
Right so a few years ago I was diagnosed with congenital fourth nerve palsy when I went to my GP and told him I had double vision when I look to the left. I was then sent to a specialist and diagnosed. This was when I was 15.
I'm 20 now and have decided I want to join the military but double vision is a bar to entry.
So here's my condition fully explained. I look to the left and my right eye drifts upwards a little bit. If I really try, I can lessen the deviation. When I close or cover my right eye and open it again, it will have drifted upwards. The same thing happens when I close my left eye, but the deviation isn't as much. I alos find it harder to keep my eyes aligned if I'm extremely tired.
Since my eyes are aligned 90% of the time I have perfect binocular vision. The eye specialist said there was no point doing anything since it would never effect me doing anything. Unfortunately it closes a certain career path...
Does anyone know if corrective surgery is possible, and given my description above, the chances of removing the double vision entirely?
Thanks for all replies, much appreciated.
Re: Fourth nerve palsy and double vision
This really depends on the measurements of your congenital fourth nerve palsy in terms of surgical correction. For some minor congenital fourth nerve palsies the reason the eye drifts up is because the inferior oblique muscle in the eye affected with the palsy acts unopposed by the 'weak' superior oblique muscle (which is the muscle supplied by the fourth nerve, an alternate name for your condition being congenital superior oblique palsy) . Hence by 'weakening' the inferior oblique muscle by myectomy (they cut a bit out) or disinsertion from the globe of the eye (the muscle reattaches itself further back) this could reduce the deviation in any meaningful gaze to the point of being considered a cure.
This type of surgery, if you were a suitable candidate, is relatively safe and effective. Occasionally with these surgeries the condition is undercorrected and another eye muscle may need to be operated on. However, overcorrection is not a significant risk, which is unlike many types of eye muscle surgery where it is a prime reason not to operate. If you overcorrect a deviation then you have double vision in the opposite direction your brain can't control = bad. You might think operating on the affected superior oblique muscle is the sensible thing to do, but surgically it is not and carries far more risks. As your fourth nerve palsy is congenital it may be more to do with a mechanical dysfunction of the superior oblique tendon rather than an actual palsy of the fourth cranial nerve.
So it all depends on the measurements of your palsy, and the specialist you see. Not all ophthalmologists (eye doctors) are the same and have the same experience or expertise. It may be worth getting a second or third opinion. Check out the credentials of the ophthalmologists you see to ensure they specialise in strabismus (a strabismologist). You have a cyclovertical strabismus/squint/eye muscle imbalance.
They may also consider if the double vision or head tilting (something most people with congenital fourth nerve palsy do to reduce their double vision and may be unaware of) is becoming a problem. So if your double vision is becoming more frequent or the head tilting is causing neck pain these may be considered reasons to operate. And these symptoms generally worsen with age.
In so far as the military are concerned I do not know if they would accept surgical correction.
If your condition were not affecting you, you wouldn't be getting double vision and the military would let you in.
Re: Fourth nerve palsy and double vision
The trochlear nerve (CN4) only controls the superior oblique. This muscle has a funny course, and runs through a pulley at the superior-medial wall of the eye socket. Because of this change in direction, the superior oblique muscle works mainly as an intonate, though it does perform some vertical movement, especially when the eye looks medially. Patients will often complain of a vertical diplopia, especially when looking away from the lesion. They may develop a head-tilt away from the affected eye. On cross cover testing, you’ll find a vertical hypertrophy of the affected eye that worsens when that eye is looking medially toward the nose, especially when reading.
Fourth nerve palsies can occur from DM/HTN ischemia, like all palsies. They can also be:
* Trauma (that fourth nerve pops off the dorsally and has a long course to traverse)
* Congenital palsy that decompensates with age
Thanks And Regards.
Simon Joseph :cool:
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