Diagnosing optic nerve disease in pets

In this dvm360® interview, Joshua J. Broadwater, DVM, DACVO, with Charlotte Animal Referral & Emergency in North Carolina, emphasizes the importance of a good retinal exam to identify common optic nerve diseases.

Broadwater will be delivering ophthalmology lectures at our Fetch Charlotte conference taking place March 15-17, 2024. Register here today to secure your spot.

The following is a partial transcript of the video.

Joshua J. Broadwater, DVM, DACVO: When we look at the optic nerves when we do a retinal exam, it can be tricky especially for cats because cats, their optic nerve is going to look similar in all situations whether it's healthy, whether it's diseased, it's hard to really get a feel for what may be going on. With dogs, it's a lot easier to tell. And that's where performing a good retinal exam with either direct or indirect ophthalmoscopy would be good. Getting used to looking at what is a normal optic nerve, so you know what is an abnormal optic nerve is also really important.

But, when we are examining the optic nerve, there's a couple things to note. So when you look at it, we should normally see this structure that is almost flat against the back of the eye, pale pink to tan in color, with blood vessels coursing over it. In different diseases, it's going to appear different ways so it can appear swollen and red when there are situations like optic neuritis, when the nerve is inflamed, which can happen for several reasons. It can be just a primary disease like optic neuritis, you can see that secondary to things like acute glaucoma as well. But in diseases like optic neuritis, you will see this optic nerve looking raised. So, it'll look closer to you when you're doing your retinal exam. And when you're able to appreciate the depth perception, you will see these blood vessels that normally just course over the optic nerve, you'll see that as they leave the optic nerve, they kind of drop off because the optic nerve is truly raised.

So, you're trying to appreciate that depth perception of a raised, swollen, red optic nerve with the blood vessels kind of dipping down over it. So, that'll give you an idea that the optic nerve is inflamed. Versus the opposite of that, if the optic nerve is cupped, then what you're going to see is it's going to be basically cupped inwards away from you.

For more on veterinary ophthalmology, Broadwater explains techniques for examining the vitreous, retina, and optic nerve head here.