| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (LN) Class of 2023, Baylor College of Medicine, Houston, Texas |
| Description |
Summary: • Disc edema can lead to stress, causing deformation of the peripapillary region. o Stress lines: compressive, tensile, or shearing o When stress exceeds the tensile strength, rupture results • Paton's Lines = intraretinal folds, retinal folds, choroidal folds, or peripapillary wrinkles (PPW) • Paton's lines may have 3 distinct patterns: o Concentric to disc, spiral, or radial • OCT(spectral domain OCT) allows for the differentiation of Paton's Lines |
| Transcript |
So today we're going to be talking about Paton's Lines. And Leslie Patondid not have OCT, so a lot of things are kind of lumped into what we see ophthalmoscopically as lines in the back of the eye. The ones of neuroophthalmic significance are the ones that are related to the disk. So, when we have a swollen disc, disc edema, it can exert stress, which is the force, and cause mechanical deformation of the peripapillary region. And that peripapillary deformation is called strain. So, the mechanical deformation is what the tissue feels in response to the force lines, stress. And those stress lines can be compressive, or they can be tension in hollow structures like arteries and veins, or it can be shear stress where the two stress lines (the force lines) are not actually compressing or in wall tension but are shearing. And so, the stress-strain curve defines that relationship. And so, things that are very stiff have very steep curves and that slope is called the modulus, you don't need to know that. And so, a stress-strain curve might look like this where we have increasing levels of stress leading to increased levels of strain and then there's some point where we're going to exceed the tensile strength of whatever we're dealing with and that might cause a rupture. So, for example in trauma you might get a colloidal break if it ruptures beyond the tensile strength of the back of the eye. But for our purposes, Paton's Lines can be peripapillary wrinkles, they can be concentric to the disk, they can be spiral, they can be radial. So, we have all these different names for the ophthalmoscopic pattern that we see and if they're deeper and below the blood vessel that's a choroidal fold. And a choroidal fold is a deeper type of fold. On fluorescein it'll be alternating hyper and hypo, they're deeper, and you can see the vessels on top. So ophthalmoscopically we can see that there's a wrinkle, a fold or a line, but OCT, especially spectral domain OCT, tells us what layer we're at. And so, when we have a swollen optic disk on OCT, one of the things that we can see is little lines that are going up and down and that represents the peripapillary wrinkle. So, it's peri, it's around the papilla, and it lines up like little hair files or hair pins. That's a PPW, a peripapillary wrinkle. Versus the concentric spiral and radial retinal folds which are intraretinal, or they can be on the surface. So, if a surface retinal fold on OCT can be paired with a choroidal fold and RPE and the retina. So, when those little folds occur in the same pattern, we call that harmonic and when they're not together we call that disharmonic, they're not aligned. So, you can have just the choroidal folds, deeper. You can have intraretinal folds, in the retina. You can have peripapillary wrinkling or you can have the retinal folds around the surface. Those surface folds can occur with or without the choroidal folds. So sometimes you just have the choroidal folds with no retinal pathology, nothing to see. And OCT allows us to differentiate whether we're dealing with peripapillary wrinkles, retinal folds that are concentric, radial or spiral, whether there's associated choroidal folds or intraretinal folds. And the reason all of this is important is anything that causes mechanic stress at the peripapillary region will result in strain which will create the deformation. But the patterns seem to be associated with specific forms of stress. And so, the Paton's Lines that are radial or the choroidal folds, that is the pattern that we're looking for in papilledema: disc edema from increased intracranial pressure. In contrast, other forms of disc edema like NAION also are causing disc edema and exerting peripapillary force lines, but that's going to produce the concentric, but not the radial form. It can produce the concentric, but not the choroidal folds. And so, when I am looking at these lines, OCT has helped me understand where the line is. And where the line is, is helpful in differentiating the disc edema from papilledema, from the disc edema from NAION and other causes. The concentric one, though, only tells you that you have force lines there in a peripapillary region. I don't think you can rely on that one to adjudicate the question, "am I dealing with papilledema or NAION?" So, you need to know a little bit about the lines. And Leslie Paton did not have an OCT. But you do and you should use it. |
