 Good morning everyone. Thanks Tara for the introduction. I will be talking about optic dyxtrusin for today. Let's go on with the case. So this patient is a 28-year-old Caucasian female that presented to Dr. Petty's ophthalmology clinic back in June of 2013. Her chief complaint was tearing and scratching, an itching sensation of the eyes bilaterally. She was diagnosed at that moment with recurrent corneal erosion, secondary to an insufficient tear film, and the fundoscopic exam was deferred at that time. She then returned in August of this year just for a routine eye exam, and what we found is her visual acuity with correction was very good. Her right eye was 20 over 15 and left 20-20. Her intraocular pressure was within normal range at 12 bilaterally. Her confrontational fields were full and her slit lamp exam was unremarkable. Fundus exam, however, revealed optic nerve drusen bilaterally with a cup to disc ratio of 0.1. The macular periphery and blood vessels were within normal limits. Other grit testing revealed no abnormalities, and neither did the visual field exam. These are some pictures of her autofluorescent imaging of her left and right eye. As you can see, you see pockets of hyperautofluorescence that demarcate the location of the drusen. They also did some fundus photography, and again, you can see hyperlucent areas demarcating where the drusen are, especially you can see them in the margins. A little bit on optic disc drusen. This is a benign congenital condition of the optic disc, optic canal, or vasculature. It is usually an incidental finding on funduscopic exam. It is generally, like I said, very benign. Per studies, they suggest an incidence of 0.34%, however, postmortem analysis suggests a higher prevalence at 0.4 to 2%. Peridability has been suggested, but no clear pattern has been identified. It seems to run higher within families, but again, they haven't found a clear pattern of inheritance. Bilateral findings are usually seen in 75 to 85% of patients with optic disc drusen. Just a little bit on optic disc anatomy. This right here is the lamina crebrosa. This is mesh work of collagen fibers that inserts to both sides of the sclera. This is the sclera right here on both sides, through which the optic nerve runs through to exit the eye. The importance of this structure in optic disc drusen is that drusen deposits anteriorly to this lamina crebrosa. When you get enough drusen, the lamina crebrosa can displace a little posteriorly and these patches can deform and cause compression on the axons exiting the eye. A little bit on the pathophysiology. Basically, drusen are deposits of mucopolysaccharides, ribo and amino nucleic acids, calcium and iron that deposit, like I said, anterior to the lamina crebrosa. The pathology suggested for these drusen is that it's secondary to an inherited dysplastic optic canal that causes compression again of this structure called the lamina crebrosa. This, in turn, causes a narrowing of the space through which the axons go through to exit the eye. It is believed that this compression causes axonal metabolism abnormalities, therefore causing calcium ions to deposit on these right here which would represent the mitochondria. Eventually, this compression causes the axonal axons to disrupt and the calcified mitochondria extrude towards the extracellular space and eventually these calcified mitochondria coalesce to what we call drusen. There are two types of drusen in the optic nerve. There's buried versus superficial and what you see at fundoscopic exam actually depends on the time of diagnosis. So here's the evolution of drusen here. This is what we call buried dysdrusen. Buried dysdrusen is more common in childhood and what you see on fundoscopic exam is a little bit blurring of the margins and elevation of the optic disc. This is what we call an appearance of pseudo papillodema, so it is important to distinguish this from true papillodema and other pathologies. This eye is now this eye. Ten years later, as you can see, there's quite a difference. Here you can see the visible drusen, especially on the disc margins. Despite this progression of drusen, people are usually symptomatic and retain normal visual acuity. The most common symptom reported in people with optic dysdrusen are visual field defects. These defects can range from an nasal step, arcoids, scotoma, or an enlarging of the blind spot. Different studies report different incidents of visual field defects ranging from 24 to 87 percent. I know that's a big range, but it really does depend on the study that you look at. But these visual field defects, however, are very mild. Patients don't notice them because they occur over such a long period of time over decades that it really does not seem to bother the patient. These visual field defects are most common in people with superficial drusen as opposed to the buried one that you see in childhood. Differential diagnosis for optic dysdrusen include papillodema, a tilted disc, crowded disc associated with hyperopia, retinoblastoma, and astrocytic hematoma. The one I will focus more in this lecture will be papillodema, just because that is one of the most concerning diagnosis that you have to exclude, especially when you see a patient with buried disc drusen. This is a fundoscopic photograph of a person with buried disc drusen versus a person with papillodema. As you can see here in the photograph, in the person with buried disc drusen, again, you see a slight elevation of the optic nerve. You see some blurring of the margins. The optic distance does not appear hyperemic, and you can follow all the blood vessels exiting the optic nerve. This right here is just a small papillary hemorrhage. That's one of the complications of optic dysdrusen that I will discuss later. This is in comparison to papillodema here. Again, the disc here looks very swollen. You have blurring of the blood vessels exiting the disc, which is more suggestive of papillodema. Diagnostic testing that can be done to differentiate between these two pathologies include a beta-scan ultrasound. Here you have a picture of a person with optic disc drusen. This right here represents the drusen. This is a hyperechogenic focus that is in the retina optic nerve junction. This right here is the optic nerve, and right here is the retina. The degree of shadowing from this drusen depends on the size of the drusen. This is in comparison to a base scan ultrasound of a person with papillodema. In a person with increased intracranial pressure, the pressure is transmitted through the subdural space and causes an increase of the optic nerve diameter, giving it a more widened appearance, as you can see compared to this right here. Additionally, you can also see echolucin circle that demarcates the separation of the optic nerve from the optic sheath, and this is called the crescent sign. Another way to differentiate buried optic disc drusen from papillodema is through fluorescein angiography. This is a patient with optic disc drusen. Again, you see pockets of hyperfluorescence. You don't see any leaking of the dye anywhere, which is compared to right here. This is a fluorescein angiogram of a person with papillodema. Again, the optic disc looks very swollen, and you see extravasation of the dye from the vessels. OCT, from my reading, it shows that OCT is one of the best ways to monitor retinal nerve fiber layer changes from drusen over time. There was an article that was published in JAMA Ophthalmology in 2009 looking at the differences in OCT characteristics between papillodema and optic disc drusen. What they found is if the nerve fiber layer is greater than 78 millimeters, it has an 80 percent specificity and 90 percent sensitivity for papillodema. Another thing that they found is that this angle right here called the alpha angle. If it's more than 141 degrees, it is 90 percent specific for optic disc drusen. Here you see an OCT again of optic disc drusen. As you can see, the optic nerve head appears elevated. The internal contour is very irregular, and again, here is where the drusen would be. This is just to show you what a CT scan of optic disc drusen would look like if someone were to be concerned for increased intracranial pressure and did a CT scan. Here, as you can see the drusen, this is a non-contrast bone window of the orbits. Here you can see this hyper dense lesion that corresponds to the drusen. Complications of ODD include transient visual loss, pre-papillary hemorrhages, retinal vascular occlusions, and pre-papillary subrenovascularization. Transient vision loss is seen in about 8.6 percent of people with optic disc drusen. It is thought that drusen increased the interstitial pressure and decreased the perfusion pressure within the optic disc, so they have suggested that maybe changes in CSF arterial or venous pressure could cause optic disc ischemia that would be seen as a transient visual loss or graying out of your visual field. Another complication is a pre-papillary hemorrhage, as you can see right here. They are usually very superficial and single and do not affect and have very good visual prognosis. Another complication seen with optic disc drusen are retinal vascular occlusions, both arterial or venous. They tend to occur in younger patients about in their mid-20s, and this is thought to result from the crowding and compression of the vessels that are going through the lamina kerbrosa by the drusen. And last but not least, there's the pre-papillary subrenovascularization. This is a very rare complication of optic disc drusen, nevertheless it has been documented. Here on this picture you see the drusen around the optic nerve and temporal to the optic nerve, you see this area of hyperpigmentation that demarcates the neovascularization. This complication is usually mild and self-resolving, however if it's around the macular and central visual acuity is compromised, laser photocoagulation has been suggested as a treatment. For treatment, there is no treatment proven to alter the course of optic disc drusen. Like I said, it's generally a very benign disease that doesn't cause a lot of visual abnormalities. Nevertheless, through my readings they said that you should have a baseline visual field testing at the time of diagnosis just to have a background in case a person develops other ocular pathologies that can compromise visual fields such as glaucoma. Like I said, one of the visual field defects that you can see in optic disc drusen are nasal steps and arquids, gutomas, which can also be seen in glaucoma. They also recommend that patients be followed with serial visual field exams, optic nerve fiber analysis, and repeat intraocular pressure checks. It doesn't say how often you should do it. I think it just depends on the physician and if the patient is having any sort of visual field defects. That's my bibliography. Any questions? I'm sorry, what condition did you say? Oh, yes. There is some association, but they didn't find very many. It was very few documented cases, which is why I didn't put it up as one of the complications, but it would be non-harturitic, anterior optic ischemic neuropathy that they think is secondary to compression of drusen. No, from my reading they said that just the compression causes this abnormal sort of metabolism within the axon and the calcium ions within the axon start depositing in the mitochondria and once the axon disrupts, they just protrude out and more calcium ions that are in the extracellular space deposit on the mitochondria and eventually these mitochondria somehow coalesce and form the drusen. They have a very high concentration of calcium ions. The reason why they're hyperfluorescent is that we don't know what ingredients within the drusen that cause it to out up for us. Thank you.