Title: Where are the defects coming from… , , or could it be both?

Authors: Rachel Goretsky OD, Biana Gekht OD Abstract: Optic disc drusen and glaucoma cause similar retinal nerve fiber layer(RNFL) as well as visual field defects. This paper describes a patient who has both conditions and the management involved. I. Case History: 66 year old African-American male presents for dilation and imaging. Patient has a history of Glaucoma for several years; he is taking Brimonidine bid OU and Latanoprost qhs OU with reported good compliance. Medical & Ocular History: • Hypertension, gout, cholesterol and stents placed in leg and chest. Glaucoma OU. History of peripheral iridotomy OU one year ago. Medications:Amplodipine, clopidogrel, allopurinol II. Pertinent findings: • Maximum pressure history is 17 OD, 19 OS, current visit 16 OD, 19 OS • Anterior chamber : Grade 2 Van Herick Angles OU • Iris: Peripheral Iridotomy, patent at 12 o’clock OD,OS • Optic disc: 0.3r OD, OS small nerves, mild blurry margins indicative of disc drusen • Macula: diffuse OU • Pachymetry : 556 OD/ 566 OS • Gonioscopy: open to trabecular meshwork (TM) superiorly, otherwise no structures visible OD, open to TM inferiorly, otherwise no structures visible OS • Spectralis Optical Coherence Tomography(OCT): optic disc drusen with small cups and disc area OU • Visual field exhibited no defects OD, inferior nasal defects OS. III. Differential Diagnosis: • , tilted discs, pseudotumor cerebri, myelinated nerve fiber layer IV. Diagnosis and Discussion head drusen are hyaline deposits made of calcium phosphate as well as amino acids, among other materials. These become calcified as axonal degeneration prevails in the optic nerve head. The scleral canal becomes increasingly narrow, thus damaging the surrounding tissue which is thinner superiorly and inferiorly. Defects from drusen include an enlarged blind spot, as well as inferior nasal and arcuate . Studies have stated that more superficial drusen cause more significant visual field defects than drusen located closer to the lamina cribrosa. Research has shown that as people age, optic drusen becomes more visible due to tissue thinning in front of the deposits, no longer obscuring them as much as before. V.Treatment and Management This patient had more visible optic drusen, which have been noted before he was diagnosed with glaucoma. Over the last several years, he started to exhibit RNFL thinning and exhibiting visual field defects, particularly in the inferior nasal quadrant of the left eye. Fundus photos were taken on the Eidon camera, as well as with Spectralis and Cirrus OCT. Photos revealed an inferior wedge defect OD, and a superior temporal and inferior temporal wedge defect OS, corresponding to the visual field defects. Scans were taken through the center of the optic nerve, exhibiting optic nerve head elevation and the hyporeflective areas representing the drusen. This appearance can sometimes be confused for optic disc edema, except that edema exhibits a smoother internal surface, in to drusen, which give a very bumpy irregular internal surface. It is very challenging to attribute what the field loss coming from either glaucoma, or the drusen, which can grow slowly in size over time. This patient has hypertension as well, and vascular occlusions are more likely to occur in such a crowded optic nerve space. There is no treatment for optic nerve head drusen, except for careful monitoring, particularly for field loss. If concurrent glaucoma exists, topical or laser procedures will usually be treatment used. VI. Conclusion When analyzing loss of the RNFL or the visual field, it is important to note whether glaucoma, optic drusen, or both. It is important to keep track of visual field defects attributed solely to the optic nerve head drusen if they have been present before glaucoma has become a coexisting condition. It is useful to establish an idea of the baseline visual field defects from the drusen to have a reference when starting to manage the glaucoma as well. This patient has coexisting glaucoma and optic nerve head drusen, and it is unclear what exactly is causing the visual field defects, but the important thing is to make sure to effectively treat the glaucoma to create as little stress as possible on the small space involved. There is an abundance of mechanical stress on the prelaminar region of the scleral canal, with the additional burden of drusen compressing the ganglion cell axons, along with too high of an . Imaging technology such as OCT’s and visual fields greatly aid the diagnosis and continued management of this pathology. VII. References

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