Optic disc drusen

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Optic disc drusen
Classification and external resources
ICD-10 H47.3
ICD-9 377.21, 377.24
OMIM 177800
DiseasesDB 31338
eMedicine oph/615 
MeSH D015594

Optic disc drusen (ODD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc[1].[2] They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells [3]. [4][5] ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, optic nerve head drusen and disc hyaline bodies [6]. They may be associated with vision loss of varying degree.

Contents

[edit] Anatomy

The optic nerve is a cable connection that transmits images from the retina to the brain. It consists of over one million retinal ganglion cell axons. The optic nerve head, or optic disc is the anterior end of the nerve that is in the eye and hence is visible with an ophthalmoscope. It is located nasally and slightly inferior to the macula of the eye. There is a blind spot at the optic disc because there are no rods or cones beneath it to detect light. The central retinal artery and vein can be seen in the middle of the disc as it exits the scleral canal with the optic nerve to supply the retina. The vessels send branches out in all directions to supply the retina.


[edit] Epidemiology

Optic disc drusen are found clinically in about 1% of the population but this increases to 3.4% in individuals with a family history of ODD. About two thirds to three quarters of clinical cases are bilateral. [1] A necropsy study of 737 cases showed a 2.4% incidence with 2 out of 15 (13%) bilateral, [2] perhaps indicating the insidious nature of many cases. An autosomal dominant inheritance pattern with incomplete penetrance and associated inherited dysplasia of the optic disc and its blood supply is suspected [7][8]. Males and females are affected at equal rates. Caucasians are the most susceptible ethnic group. Certain conditions have been associated with disc drusen such as retinitis pigmentosa, angioid streaks, Usher syndrome, Noonan syndrome [9] and Alagille syndrome[10][1]. Optic disc drusen are not related to Bruch membrane drusen of the retina which have been associated with age-related macular degeneration [6].

[edit] Pathophysiology

In children, optic disc drusen are usually buried and undectectable by fundoscopy except for a mild or moderate elevation of the optic disc. With age, the overlying axons become atrophied and the drusen become exposed and more visible. They may become apparent with an ophthalmoscope and some visual field loss at the end of adolescence. [11] ODD can compress and eventually compromise the vasculature and retinal nerve fibers. Rarely, choroidal neovascularization may develop as the juxtapapillary nerve fibers are disrupted, with subsequent subretinal hemorrhage and retinal scarring[6]. Even more rarely, vitreous hemorrhage may develop[12].

[edit] Clinical Features

On fundoscopic examination, the optic disc is small and often missing the optic cup. The optic disc also appears elevated and is classically described as having lumpy-bumpy or scalloped borders. The pattern of retinal vessel branching may be deranged. Superficial optic disc drusen are seen as round white-yellow granules located in any part of the disc, most often nasally[6]. Superficial ODD are also autofluorescent on red free ophthalmoscopy or fundus photography and can be seen with fluorescein angiography [1]. Drusen buried within the disc are more difficult to detect without an imaging study [13] [14]. Buried drusen calcifications can be detected most effectively by B-scan sonography [13]. Computerized tomography can also pick up calcified lesions. [15]. False negative results are more common in young children in whom ODD have not yet calcified. In 70% of cases, drusen affect the optic disc bilaterally[1]. If there is significant asymmetric optic disc involvement, an afferent pupillary defect may be obvious[6].

[edit] Prognosis

Optic nerve damage is progressive and insidious. Eventually 75% of patients will develop some peripheral field defects. These can include nasal step defects, enlarged blind spots, arcuate scotomas, sectoral field loss and altitudinal defects [6]. Clinical symptoms correlate to visibility of the drusen. [16] Central vision loss is a rare complication of bleeding from peripapillar choroidal neovascular membranes. Anterior ischemic optic neuropathy is a potential complication [17].

[edit] Differential diagnosis

In most patients, optic disc drusen are an incidental finding. It is important to differentiate them from other conditions that present with optic disc elevation, especially papilledema which could imply raised intracrainal pressure or tumors. True papilledema may present with exudates or cotton-wool spots, unlike ODD. The optic disc margins are characteristically irregular in ODD but not blurred as there is no swelling of the retinal nerve fibers. Spontaneous venous pulsations are present in about 80 percent of patients with ODD, but absent in cases of true disc edema [6]. Other causes of disc elevation clinicians must exclude may be: hyaloid traction, epipapillary glial tissue, myelinated nerve fibres, scleral infiltration, vitreopapillary traction and high hyperopia. [18] Disorders associated with disc elevation include: Alagille syndrome, Down syndrome, Kenny-Caffey syndrome[19], Leber Hereditary Optic Neuropathy and linear nevus sebaceous syndrome [20].

[edit] Management

Patients with optic disc drusen should be monitored periodically for fundoscopy, Snellen acuity, contrast sensitivity, color vision, intraocular pressure and threshold visual fields[6]. For those with visual field defects optical coherence tomography has been recommended for follow up of nerve fiber layer thickness [21]. Associated conditions such as angioid streaks and retinitis pigmentosa should be screened for. Both the severity of optic disk drusen and the degree of intraocular pressure elevation have been associated with visual field loss.[16] [22] There is no widely accepted treatment for ODD, although some clinicians will prescribe eye drops designed to decrease the intra-ocular pressure and theoretically relieve mechanical stress on fibers of the optic disc. Rarely choroidal neovascular membranes may develop adjacent to the optic disc threatening bleeding and retinal scarring. Laser treatment [23]or photodynamic therapy[24] or other evolving therapies [25]may prevent this complication.

[edit] References

  1. ^ a b c d e Golnik, K. (2006). Congenital anomalies and acquired abnormalities of the optic nerve, (Version 14.3). UptoDate (On-Line Serial)
  2. ^ a b A H Friedman, S Gartner, and S S Modi. Drusen of the optic disc. A retrospective study in cadaver eyes. Br J Ophthalmol. 1975 August; 59(8): 413-421 PMID 1064209 PubMed Central Full text
  3. ^ Rosen, E. (2005) Optic disc drusen and acute vision loss. Harefuah:144, 785-9, 822. PMID 16358654
  4. ^ Tso MO. Pathology and pathogenesis of drusen of the optic nerve head. Ophthalmology. 1981;88:1066-1080.PMID 7335311
  5. ^ Kapur R, Pulido JS, Abraham JL, Sharma M, Buerk B, Edward DP. Histologic findings after surgical excision of optic nerve head drusen. Retina. 2008 Jan;28(1):143-6.PMID 1818515
  6. ^ a b c d e f g h No Author. (2001) Optic Nerve Head Drusen In: Handbook of Ocular Disease Management [On-line]. Available: Jobson Publishing L.L.C. www,revoptom.com/HANDBOOK/SECT50a.HTM
  7. ^ Antcliff RJ, Spalton DJ. Are optic disc drusen inherited? Ophthalmology. 1999 Jul;106(7):1278-81. PMID 10406605
  8. ^ Riordan-Eva, P. & Hoyt, W.F. (2004) Neuro-ophthalmology. In P.R. Riordan-Eva & J.P. Whitcher (Eds.), General Ophthalmology, 16th Edition, (pp. 261-306). New York: Lange Medical Books/McGraw-Hill
  9. ^ Noonan syndrome OMIM 163950
  10. ^ Nischal KK, Hingorani M, Bentley CR, Vivian AJ, Bird AC, Baker AJ, Mowat AP, Mieli-Vergani G, Aclimandos WA. Ocular ultrasound in Alagille syndrome: a new sign. Ophthalmology. 1997 Jan;104(1):79-85. PMID 9022108
  11. ^ Spencer TS, Katz BJ, Weber SW, Digre KB. Progression from anomalous optic discs to visible optic disc drusen. J Neuroophthalmol. 2004 Dec;24(4):297-8. PMID 15662245
  12. ^ Horton, J. (2005). Disorders of the Eye. In D. L. Kasper, E. Braunwald, A.S. Fauci, S.L. Hauser, D.L. Longo, J.L. Jameson, & K.J. Isselbacher (Eds.) Harrison’s Principles of Internal Medicine, 16th Edition. [On-line]
  13. ^ a b Kurz-Levin MM, Landau K. A comparison of imaging techniques for diagnosing drusen of the optic nerve head. Arch Ophthalmol. 1999 Aug;117(8):1045-9. PMID 10448747 Full text
  14. ^ R Haynes, A Manivannan, S Walker, P Sharp, and J Forrester. Imaging of optic nerve head drusen with the scanning laser ophthalmoscope. Br J Ophthalmol. 1997 August; 81(8): 654-657. PMID 9349152 PMCID PMC1722286
  15. ^ Obuchowska I (2004). New approaches towards pathogenesis, diagnosis, natural course and complications of optic disc drusen. Klin Oczna:106, 98-101 PMID 15218776
  16. ^ a b Wilkins JM, Pomeranz HD. Visual manifestations of visible and buried optic disc drusen. J Neuroophthalmol. 2004 Jun;24(2):125-9. PMID 15179065
  17. ^ Purvin V, King R, Kawasaki A, Yee R. Anterior ischemic optic neuropathy in eyes with optic disc drusen. Arch Ophthalmol. 2004 Jan;122(1):48-53. PMID 14718294 Full text
  18. ^ Brodsky, MC. In: Congenital anomalies of the optic disc: Pseudopapilledema associated with optic disc drusen. Ch 3. pp 178-187 In: Miller NR, Newman NJ eds. Walsh and Hoyt's Clinical Neuro-ophthalmology, 6th edition. 2005. Lippincott Williams & Wilkins Google books
  19. ^ Kenny-Caffey Syndrome type 2 OMIM 12700
  20. ^ SCHIMMELPENNING-FEUERSTEIN-MIMS SYNDROME OMIM 163200
  21. ^ Calvo-González C, Santos-Bueso E, Díaz-Valle D, Reche-Frutos J, Moriche-Carretero M, Benítez-Del-Castillo JM, García-Sánchez J. Optic nerve drusen and deep visual fields defects. Arch Soc Esp Oftalmol. 2006 May;81(5):269-73. PMID 16752318
  22. ^ Grippo TM, Shihadeh WA, Schargus M, Gramer E, Tello C, Liebmann JM, Ritch R. Optic Nerve Head Drusen and Visual Field Loss in Normotensive and Hypertensive Eyes. J Glaucoma. 2008 Mar;17(2):100-104. PMID 18344754
  23. ^ Delyfer MN, Rougier MB, Fourmaux E, Cousin P, Korobelnik JF. Laser photocoagulation for choroidal neovascular membrane associated with optic disc drusen. Acta Ophthalmol Scand. 2004 Apr;82(2):236-8. PMID 15043550
  24. ^ Chaudhry NA, Lavaque AJ, Shah A, Liggett PE. Photodynamic therapy for choroidal neovascular membrane secondary to optic nerve drusen. Ophthalmic Surg Lasers Imaging. 2005 Jan-Feb;36(1):70-2. PMID 15688974
  25. ^ Sivaprasad S, Moore AT. Choroidal neovascularisation in children. Br J Ophthalmol. 2008 Apr;92(4):451-4. PMID 18369058

[edit] External links

  • Brodsky, MC. In: Congenital anomalies of the optic disc: Pseudopapilledema associated with optic disc drusen. Ch 3. pp 178-187 In: Miller NR, Newman NJ eds. Walsh and Hoyt's Clinical Neuro-ophthalmology, 6th edition. 2005. Lippincott Williams & Wilkins Google books
  • OMIM 177800 Pseudopapilledema
  • Wirtschafter JD. Optic nerve axons and acquired alterations in the appearance of the optic disc. Trans Am Ophthalmol Soc. 1983;81:1034-91. PMID 6203209
  • North American Neuro-Ophthalmological Society patient information
  • Vishal Patel and Thomas A. Oetting, MD. Optic Nerve Drusen: 19 year-old female with blurred vision. August 14,2007 U of Iowa eye rounds case study
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