Optic disc drusen

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) or optic nerve head drusen (ONHD) 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, and disc hyaline bodies.^[6] They may be associated with vision loss of varying degree occasionally resulting in blindness.

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.

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.^[1][10] Optic disc drusen are not related to Bruch membrane drusen of the retina which have been associated with age-related macular degeneration.^[6]

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]

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.^[13] Central vision loss is a rare complication of bleeding from peripapillar choroidal neovascular membranes. Anterior ischemic optic neuropathy (AION) is a potential complication.^[14]

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 intracranial 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.^[15] Disorders associated with disc elevation include: Alagille syndrome, Down syndrome, Kenny-Caffey syndrome,^[16] Leber Hereditary Optic Neuropathy and linear nevus sebaceous syndrome.^[17]

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.^[18] 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.^[13][19] 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^[20] or photodynamic therapy^[21] or other evolving therapies^[22] may prevent this complication.

See also

• Drusen

References

1. ^ ^{a b c} Golnik, K. (2006). Congenital anomalies and acquired abnormalities of the optic nerve, (Version 14.3). UptoDate (On-Line Serial)
2. ^ ^{a b} Friedman AH, Henkind P, Gartner S (April 1975). "Drusen of the optic disc. A histopathological study". Trans Ophthalmol Soc U K 95 (1): 4–9. PMID 1064209. 
3. ^ Rosen E, Almog Y, Assia E (November 2005). "[Optic disc drusen and acute vision loss]" (in Hebrew). Harefuah 144 (11): 785–9, 822. PMID 16358654. 
4. ^ Tso MO (October 1981). "Pathology and pathogenesis of drusen of the optic nervehead". Ophthalmology 88 (10): 1066–80. PMID 7335311. 
5. ^ Kapur R, Pulido JS, Abraham JL, Sharma M, Buerk B, Edward DP (January 2008). "Histologic findings after surgical excision of optic nerve head drusen". Retina (Philadelphia, Pa.) 28 (1): 143–6. doi:10.1097/IAE.0b013e31815e98d8. PMID 18185151. 
6. ^ ^{a b c d e f} "Optic Nerve Head Drusen". Handbook of Ocular Disease Management. Jobson Publishing L.L.C.. 2001. http://www.revoptom.com/HANDBOOK/SECT50a.HTM. 
7. ^ Antcliff RJ, Spalton DJ (July 1999). "Are optic disc drusen inherited?". Ophthalmology 106 (7): 1278–81. doi:10.1016/S0161-6420(99)00708-3. PMID 10406605. 
8. ^ Riordan-Eva P, Hoyt WF (2004). "Neuro-ophthalmology". In John P. Whitcher; Riordan-Eva, Paul; Vaughan, Daniel; Asbury, Taylor. Vaughan & Asbury's general ophthalmology (16th ed.). New York: Lange Medical Books/McGraw-Hill. pp. 261–306. ISBN 0-07-137831-6. 
9. ^ Online 'Mendelian Inheritance in Man' (OMIM) Noonan syndrome -163950
10. ^ Nischal KK, Hingorani M, Bentley CR, et al (January 1997). "Ocular ultrasound in Alagille syndrome: a new sign". Ophthalmology 104 (1): 79–85. PMID 9022108. 
11. ^ Spencer TS, Katz BJ, Weber SW, Digre KB (December 2004). "Progression from anomalous optic discs to visible optic disc drusen". J Neuroophthalmol 24 (4): 297–8. PMID 15662245. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=1070-8022&volume=24&issue=4&spage=297. 
12. ^ Horton, J. (2005). "Disorders of the Eye". In Jameson JN, Kasper DL, Harrison TR, Braunwald E, Fauci AS, Hauser SL, Longo DL.. Harrison's principles of internal medicine (16th ed.). New York: McGraw-Hill Medical Publishing Division. ISBN 0-07-140235-7. http://highered.mcgraw-hill.com/sites/0071402357/information_center_view0/. 
13. ^ ^{a b} Wilkins JM, Pomeranz HD (June 2004). "Visual manifestations of visible and buried optic disc drusen". J Neuroophthalmol 24 (2): 125–9. PMID 15179065. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=1070-8022&volume=24&issue=2&spage=125. 
14. ^ Purvin V, King R, Kawasaki A, Yee R (January 2004). "Anterior ischemic optic neuropathy in eyes with optic disc drusen". Arch. Ophthalmol. 122 (1): 48–53. doi:10.1001/archopht.122.1.48. PMID 14718294. 
15. ^ Brodsky, MC (2005). "Ch 3: Congenital anomalies of the optic disc: Pseudopapilledema associated with optic disc drusen". In Hoyt, William Graves; Miller, Neil; Walsh, Frank. Walsh and Hoyt's clinical neuro-ophthalmology (6th ed.). Hagerstwon, MD: Lippincott Williams & Wilkins. pp. 178–87. ISBN 0-7817-4811-9. http://books.google.com.au/books?id=ATTlVWi3mvwC&pg=PA151&source=gbs_toc_r&cad=0_0&sig=-99rk1e21lLxQO20Kpp8gSgGPQk#PPA178,M1. 
16. ^ Online 'Mendelian Inheritance in Man' (OMIM) Kenny-Caffey Syndrome type 2 -127000
17. ^ Online 'Mendelian Inheritance in Man' (OMIM) Schimmelpenning-Feuerstein-MIMS Syndrome -163200
18. ^ Calvo-González C, Santos-Bueso E, Díaz-Valle D, et al (May 2006). "[Optic nerve drusen and deep visual fields defects"] (in Spanish; Castilian). Arch Soc Esp Oftalmol 81 (5): 269–73. PMID 16752318. http://www.oftalmo.com/seo/2006/05may06/05b.htm. 
19. ^ Grippo TM, Shihadeh WA, Schargus M, et al (March 2008). "Optic nerve head drusen and visual field loss in normotensive and hypertensive eyes". J. Glaucoma 17 (2): 100–4. doi:10.1097/IJG.0b013e31814b995a. PMID 18344754. 
20. ^ Delyfer MN, Rougier MB, Fourmaux E, Cousin P, Korobelnik JF (April 2004). "Laser photocoagulation for choroidal neovascular membrane associated with optic disc drusen". Acta Ophthalmol Scand 82 (2): 236–8. doi:10.1111/j.1600-0420.2004.00231.x. PMID 15043550. 
21. ^ Chaudhry NA, Lavaque AJ, Shah A, Liggett PE (2005). "Photodynamic therapy for choroidal neovascular membrane secondary to optic nerve drusen". Ophthalmic Surg Lasers Imaging 36 (1): 70–2. PMID 15688974. 
22. ^ Sivaprasad S, Moore AT (April 2008). "Choroidal neovascularisation in children". Br J Ophthalmol 92 (4): 451–4. doi:10.1136/bjo.2007.124586. PMID 18369058. 

External links

• Online 'Mendelian Inheritance in Man' (OMIM) Pseudopapilledema -177800
• Wirtschafter JD (1983). "Optic nerve axons and acquired alterations in the appearance of the optic disc". Trans Am Ophthalmol Soc 81: 1034–91. PMC 1312472. PMID 6203209. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1312472. 
• North American Neuro-Ophthalmological Society: Patient Information on Drusen
• 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