fourth nerve palsy

This is a paralysis or stroke to the fourth cranial nerve. This nerve controls a single eye muscle called the superior oblique muscle.  This muscle is located behind the eyeball and it helps the eye look downward and assists with eye rotation when you tilt your head sideways. When the nerve is blocked, this muscle stops working, and people complain of vertical double vision where objects look stacked on top of each other.  The double vision may get worse when looking to the side or trying to read a book. Fourth nerve palsies can be subtle. In fact, this is the hardest cranial nerve palsy to detect as the eyes appear normal to casual inspection.  There are many causes for a 4th nerve palsy: congenital, trauma, vascular insults (hypertension/diabetes), and lesions in the brain.  If there isn’t an obvious cause for a nerve palsy, then further imaging such as MRI should be obtained.  If the double vision persists, prism glasses are an option as is strabismus surgery.

Dr. Timothy Root is a practicing ophthalmologist and cataract surgeon in Daytona Beach, Florida. His books, video lectures, and training resources can be found at:


  1. When my eye doctor told me that I had a 4th nerve palsy, I had a had time following his conversation. This explanation was very simple and to the point. I thank you for this informative website.

  2. I’ve had 4th nerve palsy now for around 15 months. I’m a bit confused here. I woke up with vertical diplopia in August, 2012 and an opthlamologist confirmed 4th nerve palsy. He had me wait a month, then I returned for a visual fields test, which I passed with flying colors, so he said no CT or MRI was necessary. However, I had extremely high blood pressure, so I went to an internist and got put on meds. I also learned I had Type 2 diabetes. Oh, and sleep apnea, too. They don’t know what caused my 4th nerve palsy, but the high BP and diabetes could have been the culprit, if not both. But this is what puzzles me: The funky vision cleared up after about 3-4 months, but every once in a while, I have a relapse that lasts a week or two, then it clears up again. My B/P is now normal and my diabetes is well under control with an A1C of 5.8. As for the apnea, I have a CPAP, but I stopped using it after a few weeks, because it’s a pain. From what I keep reading, if my 4th nerve palsy was caused by either hypertension or diabetes, it should have resolved in 3-6 months, but as I stated, it keeps coming back for brief stints. Is it possible that I’m depriving my brain of oxygen by not using the CPAP like I should, and this is affecting that nerve, or am I just one of those people that simply didn’t completely heal? My regular optometrist told me that if I still have the condtion next time I see him, I’m looking at getting about 1.5-2 diopters of base down prism in my OS lens.

  3. @Patrick: I doubt the CPAP is causing the problem. Even with vasculopathic palsies, healing may not completely repair the damage. Many people have residual double vision and SOME people have NO improvement from day one. The prism should help.

  4. Thanks for replying so fast. It’s very reassuring to learn that some people simply don’t heal completely and have residual issues. I’m pretty sure I’ll be getting that prism put in next time. It’s a good thing I gave up contact lenses. I’m 54, and as soon as I got on the north side of 40, I couldn’t stand having them in my eyes for more than a couple of hours, and since I’m now a presbyope, anyway, I just wear glasses all the time. I may look into getting the prism just ground in one pair, and keeping the other pair prism-free for the times I see clearly without it. I have about 3 pairs of glasses, anyway……

  5. I’m a former NFL player and was diagnosed with 4th cranial nerve palsy about 14 years age by a neuro ophthalmologist at the mayo clinic in Jacksonville, FL. The diagnosis came during training camp in 2000 after repeated collisions and subsequent onset of diplopia. The initial vision impairment was extreme and eventually led to my early retirement! My question to you is there any rehabilitation to help my Diplopia? I was told initially that my vision may come back to normal or it may not. Well it’s been 14 years now and it’s gotten better since the initial injury but I still cannot lay on my left side and a long list of other issues.

  6. Hi,

    I was wondering if you could go into more depth on the vascular causes? Do aneurysms cause 4th nerve palsies? Where would they have to occur if they do?

    Any clarification would be appreciated. Thank you

  7. Richard: Sounds like a traumatic nerve palsy. I’m not aware of any non-surgical therapy to help with 4th nerve palsy. The main problem with this condition is the vertical (up and down) doubling. Our eyes aren’t designed to move separately in the vertical … unlike horizontal movements (we can voluntarily cross our eyes, for examples). This means there isn’t a way to “exercise” the muscles into the correct position. Also, 14 years of eye misalignment can’t be worked off. Your only recourse is probably surgery (not recommended if you can correct it with prism glasses).

    Gemma: that’s a bit deep for the purpose of this dictionary. I recommend you check out the super eye palsy video linked in a prior comment. Thanks!

  8. I have been diagnosed with 4th nerve palsy. I have an immunoglobulin issue which leaves me virtually no ability to fight off nasal infections. I had a shocker of a nasal infection in July this year which resulted in severe nose blowing to clear the mucus. Could a severe infection like this cause Palsy in the nerve? I have not had any blunt head trauma, blood pressure is controlled but have had no further tests. I have had this palsy for about 5 months. Thank you

  9. Have been told by my eye specialist that I have 4th nerve palsy. Had it briefly on 21st September, on the 30th October had operation for membrane peeling and 3 weeks after the operation double vision just came on and has not left, and is now 30th March. Have had mri and all came back clear as well as blood tests.


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