The Difference between ONH and SOD

I have been confused by this for a very long time. Some credible online resources claim that Optic Nerve Hypoplasia (ONH), and Septo-Optic Dysplasia (SOD) are the same thing. I went on thinking that was true for the longest time, until I dug a little deeper and learned that there is, in fact, a difference.

Dr. Richard Windsor, shown discussing another condition known as Hemianopsia. (image credit)

Today, I went to the Low Vision Expo in Indianapolis to listen to Dr. Richard Windsor and his daughter speak about the advancements in assistive technology for the visually impaired. He is a world-renowned eye specialist who also happens to be my eye doctor. After his speech was over, he invited people to ask questions. I waited for the crowd to clear out, and I asked him if I could do a short interview on camera discussing ONH. He graciously agreed to do that, because he’s a great guy who just genuinely likes to help people. Thanks again for taking the time to speak with me!

I asked him to explain the differences between ONH and SOD. I’m paraphrasing, but he said that ONH is a deformation of the optic nerve in which it does not develop properly, becoming too small, or not attaching well enough to function fully. Some patients lose all of their vision, while others may only have partial vision loss. He goes into more detail in the video. Septo-Optic Dysplasia is another complication that is often seen with ONH, but there are some ONH patients that do not have SOD. They are not the same thing, SOD is a diagnosis that describes further complications related to the optic nerve being under-developed, as well as further dysfunctions within the brain. Read more here.

So… mystery solved! Unfortunately, the National Organization for Rare Disorders (NORD) is incorrectly claiming that ONH and SOD are the same thing, which has contributed to this confusion. I have contacted them and asked them to fix that (UPDATE 10/6/19: they have since corrected the misinformation. ❤️). NORD is an excellent resource for information related to rare disorders, and they cover so many rare conditions, accidents are bound to happen. I don’t hold this against them, but I do want to correct the issue.

Thank you for reading! Here is the full interview with Dr. Richard Windsor. You can find his information here.

Featured Image credit

Advertisement