Ординатура / Офтальмология / Учебные материалы / Retinal Vascular Disease Joussen Springer

131.Jonas JB, Akkoyun I, Kamppeter B, Kreissig I, Degenring RE (2005) Branch retinal vein occlusion treated by intravitreal triamcinolone acetonide. Eye 19:65 – 71

132.Jonas JB, Akkoyun I, Kamppeter B, Kreissig I, Degenring RF (2005) Intravitreal triamcinolone acetonide as treatment of branch retinal vein occlusion. Eur J Ophthalmol 15:751 – 758

133.Kaiser PK (2005) Steroids for branch retinal vein occlusion. Am J Ophthalmol 139:1095 – 1096

134.Karacorlu M, Ozedmir H, Karacorlu SA (2005) Resolution of serous macular detachment after intravitreal triamcinolone acetonide treatment of patients with branch retinal vein occlusion. Retina 25:856 – 60

135.Kawaji T, Hirata A, Awai N, Takano A, Inomata Y, Fukushima M, Tanihara H (2005) Trans-tenon retrobulbar triamcinolone injection for macular edema associated with branch retinal vein occlusion remaining after vitrectomy. Am J Ophthalmol 140:540 – 2

136.Klein R, Klein BEK, Moss SE, et al. (2000) The epidemiology of retinal vein occlusion: the Beaver Dam Eye Study. Trans Am Ophthalmol Soc 98:133 – 139

137.Kohner EM (1964) Retinal vein occlusion. Proc R Soc Med 57:816

138.Kohner EM, Dollery CT, Shahib M, et al. (1970) Experimental retinal branch vein occlusive. Am J Ophthalmol 69:778

139.Koyanagi Y (1928) Die Bedeutung der Gefässkreuzung für die Entstehung der Astthrombose der retinalen Zentralvene. Klin Mbl Augenhk 81:219 – 231

140.Koyanagi Y (1937) Die pathologische Anatomie und Pathogenese des Kreuzungsphänomens der Netzhautgefasse bei Hochdruck. Graefes Arch Ophthalmol 137:619 – 635

141.Krepler K, Ergun E, Sacu S, Richter-Muksch S, Wagner J, Stur M, Wedrich A (2005) Intravitreal triamcinolone acetonide in patients with macular oedema due to branch retinal vein occlusion: a pilot study. Acta Ophthalmol Scand 83:600 – 4

142.Kube ET, Feltgen N, Pache M, Herrmann J, Hansen LL (2005) Angiographic findings in arteriovenous dissection (sheathotomy) for decompression of branch retinal vein occlusion. Graefes Arch Clin Exp Ophthalmol 243:334 – 338

143.Kuhli C, Hattenbach LO, Scharrer I, Koch F, Ohrloff C (2002) The high prevalence of resistance to APC in young patients with retinal vein occlusion. Graefes Arch Clin Exp Ophthalmol 240:163 – 168

144.Kuhli C, Scharrer I, Koch F, Ohrloff C, Hattenbach LO (2004) Factor XII deficiency: a thrombophilic risk factor for retinal vein occlusion. Am J Ophthalmol 137:459 – 464

145.Kumagai K, Ogino N, Furukawa M, Demizu S, Atsumi K, Kurihara H, Ishigooka H (2002) Vitreous surgery for macular edema in branch retinal vein occlusion. Nippon Ganka Gakkai Zasshi 106:701 – 707

146.Kumar B, Yu D, Morgan WH, et al. (1998) The distribution of angioarchitectural changes within the vicinity of arteriovenous crossing in branch retinal vein occlusion. Ophthalmology 105:424 – 427

147.Kurimoto M, Takagi H, Suzuma K, Oh H, Nonaka A, Kiryu J, Kita M, Ogura Y, Honda Y (1999) Vitrectomy for macular edema secondary to retinal vein occlusion: evaluation by retinal thickness analyzer. Jpn J Clin Ophthalmol 53: 717 – 720

148.Lahey JM, Fong DS, Kearney J (1999) Intravitreal tissue

plasminogen activator for acute central retinal vein occlusion. Ophthalmic Surg Lasers 30:427 – 434

149.Lakhanpal RR, Javaheri M, Ruiz-Garcia H, De Juan E Jr, Humayun MS (2005) Transvitreal limited arteriovenouscrossing manipulation without vitrectomy for complicated branch retinal vein occlusion using 25-gauge instrumentation. Retina 25:272 – 280

150.Lakhanpal RR, Javaheri M, Equi RA, Humayum MS (2005) Improvement after transvitreal limited arteriovenous crossing manipulation without vitrectomy for complicated branch retinal vein occlusion using 25 gauge instrumentation. Br J Ophthalmol 89:922 – 923

151.Lang GE, Freißler K (1992) Klinische und fluoreszeinangiographische Befunde bei Patienten mit retinalen Venenastverschlüssen. Klin Monatsbl Augenheilkd 201:234 – 239

152.Larsson J, Olafsdottir E, Bauer B (1996) Activated protein C resistance in young adults with central vein occlusion. Br J Ophthalmol 80:200 – 202

153.Leber T (1877) Die Krankheiten der Netzhaut und des Sehnerven. In: Graefe A, Sämisch T (eds) Handbuch der gesamten Augenheilkunde, Pathologie und Therapie. Verlag von Wilhelm Engelmann, Leipzig, pp 521 – 535

154.Lee WH, Thompson JT, Sjaarda RN (2001) Visual acuity results in arteriovenous sheathotomy versus grid laser photocoagulation in branch retinal vein occlusion. Abstract no 3862. Poster presented at the annual meeting of the Association for Research in Vision and Ophthalmology, 2001

155.Lee H, Shah GK (2005) Intravitreal triamcinolone as primary treatment of cystoid macular edema secondary to branch retinal vein occlusion. Retina 25:551 – 5

156.Leng T, Miller JM, Bilbao KV, Palanker DV, Huie P, Blumenkranz MS (2004) The chick chorioallantoic membrane as a model tissue for surgical retinal research and simulation. Retina 24:427 – 434

157.Lerche RC, Richard G (2004) Arteriovenous sheathotomy in branch retinal vein occlusion. Klin Monatsbl Augenheilkd 221:479 – 484

158.Le Rouic JF, Bejjani RA, Rumen F, et al. (2001) Adventitial sheathotomy for decompression of recent onset branch vein occlusion. Graefes Arch Clin Exp Ophthalmol 239: 747 – 751

159.Liebreich R (1855) Apoplexia retinae. Graefes Arch Ophthalmol 1:346 – 351

160.Lip PL, Blann AD, Jones AF, Lip GY (1998) Abnormalities in haemorheological factors and lipoprotein (a) in retinal vascular occlusion: implications for increased vascular risk. Eye 12:245 – 251

161.Lowe GDO, Trope G, McArdle BM, Douglas JT, Foulds W, Forbes CD, Prentice CRM (1982) Abnormal blood viscosity and haemostasis in chronic retinal vein thrombosis. Seventh International Congress on Thrombosis, Valencia, Spain, Oct. 13 – 16, 1982

162.Lowe GDO (1986) Blood rheology in arterial disease. Clin Sci 171:137 – 146

163.Luntz MH, Schenker HI (1980) Retinal vascular accidents in glaucoma and ocular hypertension. Surv Ophthalmol 25:163 – 167

164.Mahmoud TH, Peng YW, Proia A, Davidson M, Deramo VA, Fekrat S (2002) Intravitreal tissue plasminogen activator penetrates the retinal vessels in a porcine model of vascular occlusion. Invest Ophthalmol 43:3533. Abstract

165.Maiji AB, Janarthnan M, Naduvilath TJ (1997) Signifi-

ence tomography findings after an intravitreal injection of bevacizumab (Avastin) for macular edema from central retinal vein occlusion. Ophthalmic Surg Lasers Imaging 36:336

204.Rubenstein K, Jones EB (1976) Retinal vein occlusion: long term prospects. Br J Ophthalmol 60:148 – 150

205.Saika S, Tanaka T, Miyamoto T, Ohnishi Y (2001) Surgical posterior vitreous detachment combined with gas/air tamponade for treating macular edema associated with branch retinal vein occlusion: retinal tomography and visual outcome. Graefes Arch Clin Exp Ophthalmol 239: 729 – 732

206.Salinas-Alaman A, Garcia-Layana A, Sadaba-Echarri LM, Belzunce-Manterola A (2005) Branch retinal vein occlusion treated by intravitreal triamcinolone. Arch Soc Esp Oftalmol 80:463 – 5

207.Sallmann L (1937) Zur Anatomie der Gefässkreuzungen am Augenhintergrund: Zugleich ein Beitrag zur pathologischen Anatomie des Gunn und Salusschenzeichens. Graefes Arch Ophthalmol 137:619 – 635

208.Sarici A, Muftuoglu G (2006) Intravitreal triamcinolone compared with macular laser grid photocoagulation for the treatment of cystoid macular edema. Am J Ophthalmol 141:785 – 786

209.Scat Y, Morin Y, Morel C, Haut J (1995) Retinal vein occlusion and resistance to activated protein C (in French). J Fr Ophtalmol 18:758 – 762

210.Schatz H, Yannuzzi L, Stranky TJ (1976) Retinal detachment secondary to branch vein occlusion. Part I. Ann Ophthalmol 8:1437

211.Schatz H, Yannuzzi L, Stranky TJ (1976) Retinal detachment secondary to branch vein occlusion. Part II. Ann Ophthalmol 8:1461

212.Schepens CL, Avila MP, Jalkh AE, Trempe CL (1984) Role of the vitreous in cystoid macular edema. Surv Ophthalmol 28:499 – 504

213.Scott IU, Ip MS (2005) It’s time for a clinical trial to investigate intravitreal triamcinolone for macular edema due to retinal vein occlusion: The SCORE study. Arch Ophthalmol 123:581 – 582

214.Seitz R (1962) Die Netzhautgefäße. Vergleichende ophthalmoskopische und histologische Studien an gesunden und kranken Augen. Bücherei des Augenarztes, Heft 40. Enke, Stuttgart

215.Shah GK, Sharma S, Fineman MS, Federman J, Brown MM, Brown GC (2000) Arteriovenous adventitial sheathotomy for the treatment of macular edema associated with branch retinal vein occlusion. Am J Ophthalmol 129: 104 – 106

216.Shaikh S, Blumenkranz MS (2001) Transient improvement in visual acuity and macular edema in central retinal vein occlusion accompanied by inflammatory features after pulse steroid and anti-inflammatory therapy. Retina 21: 176 – 78

217.Shahid H, Hossain P, Amoaku WM (2006) The management of retina vein occlusion: is interventional ophthalmology the way forward? Br J Ophthalmol 90:627 – 639

218.Shilling JS, Kohner EM (1976) New vessel formation in retinal branch vein occlusion. Br J Ophthalmol 60:810 – 15

219.Shilling JS, Jones CA (1984) Retinal branch vein occlusion. A study of argon laser photocoagulation in the treatment of macular oedema. Br J Ophthalmol 68:196 – 198

220.Shiraga F (2002) Evaluation of AV sheathotomy for branch retinal vein occlusion by means of fluorescein videoangi-

ography and a computer-assisted image analysis. Macular Society 25th Annual Meeting. Barcelona, Spain; June 13, 2002

221.Snyers B, Lambert M, Hardy JP (1990) Retinal and choroidal vasoocclusive disease in systemic lupus erythematosus associated with antiphospholipid antibodies. Retina 10:255 – 260

222.Soukiasian S, Lahav M, Snady-McCoy L (1989) Natural anticoagulants in retinal vein occlusions. Invest Ophthalmol Vis Sci (Suppl) 30:477

223.Sperduto RD, Hiller R, Chew E, Seigel D, Blair N, Burton TC, Farber MD, Gragoudas ES, Haller J, Seddon JM, Yannuzzi LA (1998) Risk factors for hemiretinal vein occlusion: comparison with risk factors for central and branch retinal vein occlusion: the eye disease case-control study. Ophthalmology 105:765 – 771

224.Stefansson E, Novack RL, Hatchell DL (1990) Vitrectomy prevents retinal hypoxia in branch retinal vein occlusion. Invest Ophthalmol Vis Sci 31:284 – 289

225.Stefansson E (2001) The therapeutic effect of retinal laser treatment and vitrectomy. A theory based on oxygen and vascular physiology. Acta Ophthalmol Scan 79:435 – 440

226.Staurenghi G, Lonati C, Aschero M, Orzalesi N (1994) Arteriovenous crossing as a risk factor in branch retinal vein occlusion. Am J Ophthalmol 117:211 – 213

227.Tachi N, Hashimoto Y, Ogino N (1999) Vitrectomy for macular edema combined with retinal vein occlusion. Doc Ophthalmol 97:465 – 469

228.Takahashi MK, Hikichi T, Akiba J, et al. (1997) Role of the vitreous and macular edema in branch retinal vein occlusion. Ophthalmic Surg Lasers 28:294 – 299

229.Takahashi K, Kashima T, Kishi S (2005) Massive macular hard exudates associated with branch retinal vein occlusion. Jpn J Ophthalmol 49:527 – 529

230.Talu S, Stefanut C (2004) Axial length and branch retinal vein occlusion. Oftalmologia 48:81 – 84

231.Tameesh MK, Lakhanpal RR, Fujii GY, Javaheri M, Shelley TH, D’Anna S, Barnes AC, Margalit E, Farah M, De Juan E Jr, Humayun MS (2004) Retinal vein cannulation with prolonged infusion of tissue plasminogen activator (t-PA) for the treatment of experimental retinal vein occlusion in dogs. Am J Ophthalmol 138:829 – 839

232.Tanaka TE, Muraoka K, Tokui K (1998) Retinal arteriovenous shunt at the arteriovenous crossing. Ophthalmology 105:1251 – 1258

233.Tang WM, Han DP (2000) A study of surgical approaches to retinal vascular occlusion. Arch Ophthalmol 118:138 – 143

234.Tavola A, D’Angelo SV, Bandello F, et al. (1995) Central retinal vein and branch artery occlusion associated with inherited plasminogen deficiency and high lipoprotein (a) levels: a case report. Thromb Res 80:327 – 331

235.The Branch Vein Occlusion Study Group. Argon laser photocoagulation for macular edema in branch vein occlusion. Am J Ophthalmol 98:271 – 282

236.The Eye Disease Case-Control Study Group. Risk factors for branch retinal vein occlusion. Am J Ophthalmol 116:286 – 96

237.Tekeli O, Gursel E, Buyurgan H (1999) Protein C, protein S and antithrombin III deficiencies in retinal vein occlusion. Acta Ophthalmol Scand 77:628 – 630

238.Tolosa-Villela C, Ordi-Ros J, Jordana-Comajuncosa R, et al. (1990) Occlusive ocular vascular disease and antiphospholipid antibodies. Ann Rheum Dis 49:203

242.US Census Bureau. Available at: http://eire.censusgov/ popest/data

243.Vannas S, Tarkhanan A (1960) Retinal vein occlusion and glaucoma. Br J Ophthalmol 44:583 – 589

244.Vine AK, Samama MM (1993) The role of abnormalities in the anticoagulant and fibrinolytic systems in retinal vascular occlusions. Surv Ophthalmol 37:283 – 292

245.von Michel J (1878) Die spontane Thrombose der Vena Centralis des Opticus. Graefes Arch Ophthalmol 24:37 – 70

246.Wakabayashi T, Okada AA, Morimura Y, Kojima E, Asano Y, Hirakata A, Hida T (2004) Trans-tenon retrobulbar triamcinolone infusion for chronic macular edema in central and branch retinal vein occlusion. Retina 24:964 – 967

247.Weger M, Renner W, Steinbrugger I, Cichocki L, Temmel W, Stanger O, El-Shabrawi Y, Lechner H, Schmut O, Haas A (2005) Role of thrombophilic gene polymorphisms in branch retinal vein occlusion. Ophthalmology 112:1910 – 1915

248.Weinberg D, Dodwell DG, Fern SA (1990) Anatomy of arteriovenous crossings in branch retinal vein occlusion. Am J Ophthalmol 109:298 – 302

249.Weinberg DV, Egan KM, Seddon JM (1993) Asymmetric distribution of arteriovenous crossing in the normal retina. Ophthalmology 100:31 – 36

250.Weinberg DV, Seddon JM (1994) Venous occlusive diseases of the retina. In: Albert DM, Jakobiec FA (eds) Principles and practice of ophthalmology, 1st edn, vol 2. WB Saunders, Philadelphia, pp 735 – 746

251.Weiss JN (2001) Injection of tissue plasminogen activator into a branch retinal vein in eyes with central vein occlusion. Ophthalmology 108:2249 – 2257

252.Weizer JS, Fekrat S (2003) Intravitreal tissue plasminogen activator for the treatment of central retinal vein occlusion. Ophthalmic Surg Lasers Imaging 34:350 – 352

253.Wenzler EM, Rademakers AJ, Boers GH, Gryusberg JR, Webers CA, Deutman AF (1993) Hyperhomocysteinaemia in retinal artery and vein occlusion. Am J Ophthalmol 115: 1162 – 1167

254.Wiechens B, Schroder JO, Potzsch B, Rochels R (1997) Primary antiphospholipid antibody syndrome and retinal occlusive vasculopathy. Am J Ophthalmol 123:848 – 850

255.Wiek J, Schade M, Wiederholt M, et al. (1990) Haemorheological changes in patients with retinal vein occlusion after isovolaemic haemodilution. Br J Ophthalmol 74: 665 – 669

256.Williamson TH, Rumley A, Lowe GD (1996) Blood viscosity, coagulation, and activated protein C resistance in central retinal vein occlusion: a population controlled study. Br J Ophthalmol 80:203 – 208

257.Wong TY, Larsen EK, Klein R, Mitchell P, Couper DJ, Klein BE, Hubbard LD, Siscovick DS, Sharrett AR (2005) Cardiovascular risk factors for retinal vein occlusion and arteriolar emboli: the Atherosclerosis Risk in Communities & Cardiovascular Health Study. Ophthalmology 112:540 – 547

Core Messages

Retinal arterial occlusion is characterized by a sudden, painless loss of vision

Occlusions can occur at several locations: ophthalmic artery, central retinal artery (CRAO), branch retinal arteries (BRAO) and retinal arterioles

More proximal obstructions carry a worse visual prognosis

Retinal arterial occlusion has many causes: emboli, thrombosis, hypercoagulability states, vasculitis, infections and trauma

In the acute stages occlusion is characterized by marked reduction in retinal arterial blood flow, edematous whitening of the retina and a macular red spot. Intra-arterial emboli may be visible

Many different treatments are used. However, these generally have a limited effect

A thorough systemic assessment is necessary to identify any underlying cause of the retinal arterial occlusion. Additional treatment may be needed to reduce the risk of further retinal and cerebrovascular events

21.4.1 Epidemiology

The incidence of retinal arterial occlusion is estimated to be around 0.85/100,000 per year [55]. The condition mainly affects older people, with a mean age of 60 years at presentation. The pattern and causes of retinal arterial occlusion in younger age groups are quite distinct and will be discussed separately below. Men appear to be more susceptible than women, with a male to female ratio of 2:1. There may be some differences between racial groups. For example, affected African Americans tend to be younger than Caucasians, and in contrast to Caucasians, few have carotid artery disease as a cause of their obstruction [1]. In many cases retinal arterial obstruction is associated with general cardiovascular disease risk factors: hypertension (60 %), smoking, diabetes (25 %) and hypercholesterolemia.

21.4.2Mechanisms of Retinal Arterial Obstruction

Many different causes of retinal arterial obstruction have been reported (Box 1). However, most cases are either due to an embolus from another site or to the development of a thrombosis often in association with atherosclerosis at the site of obstruction.

Box 1: Causes of retinal arterial occlusion

Emboli

Thrombosis ± atherosclerosis

Congenital thrombophilic states

Acquired thrombophilic states

Vasculitis

Infectious

Iatrogenic

Ocular abnormalities

Trauma

Vasospasm

Raised intraocular pressure

21.4.2.1 Emboli

Emboli arise from a more proximal part of the circulation, travel into the retinal arterial tree and obstruct the flow of blood. The most important source of retinal emboli is atherosclerotic disease of the carotid arteries. The point at which an embolus stops is determined by its size relative to the caliber of the vessel. Estimates of what proportion of retinal arterial occlusions is caused by emboli vary, but they probably account for about a third of all cases [33, 63]. Emboli are more commonly found in cases of branch retinal artery occlusions.

Various types of material have been found to embolize to the eye and cause arterial occlusion (Box 2). Most are cholesterol emboli (75 %) [4, 46].

These are refractile with a yellow or orange color. The less common thrombus (15 %) and calcific (10 %) emboli are usually white in color. Cholesterol emboli are associated with atherosclerotic plaques in the aorta or carotid arteries (Box 3). Several cardiac abnormalities have been identified as a source of retinal arterial emboli: valve lesions, bacterial endocar-

21 III ditis, mural thrombus, arrhythmias and atrial myxoma [22, 54]. In individuals with a patent foramen ovale paradoxical emboli have been reported, which originate from the venous circulation [42, 48]. Rare cases of fat emboli from fractures and amniotic fluid emboli have also been reported [20, 72]. Multiple emboli are seen in 10 – 20 % of cases where emboli are found, and these tend to be unilateral [39, 51].

Several large population based surveys have found asymptomatic retinal arterial emboli in about 1.4 % of adults and in 3.1 % of those over 75 years of age [39, 46]. The 10-year cumulative incidence rate has been estimated to be 1.5 % [40]. Emboli are associated with being male, increasing age, hypertension, smoking and hypercholesterolemia. In patients with asymptomatic emboli 18 % had a greater than 75 % stenosis of the carotid artery [51].

The heart is probably the source of less than 10 % of emboli [6]. In one study about half the patients with acute retinal arterial obstruction were found to have an abnormality by transthoracic echocardiogram. However, only about 10 % required specific treatment such as anticoagulation or cardiac surgery [65]. This study subdivided individuals into low and high risk of cardiac emboli based on the history and examination. “High-risk” features included a history of myocardial infarction, rheumatic fever, valve disease, bacterial endocarditis or a cardiac murmur on auscultation. Individuals without any of these features very rarely had a cardiac defect requiring treatment. Therefore, echocardiography is recommended for any patient with a “high-risk” feature and in younger patients, but is not usually routine for “low-risk” patients.

Epidemiological studies indicate that individuals with asymptomatic retinal emboli have a relative risk of 2.6 for stroke [39, 76]. Among patients with symptomatic retinal arterial obstruction individuals with visible emboli had 4 – 10 times increased risk of stroke compared to controls, while those without emboli had no increased risk [58, 18].

Box 2: Types of embolic material

Cholesterol

Thrombus

Calcific

Fat

Bacterial vegetations

Tumor

Amniotic fluid

Box 3: Sources of emboli

Carotid arteries

Atherosclerosis

Aorta

Atherosclerosis

Heart

Valvular abnormalities

Mural thrombus (post-MI)

Arrhythmias

Atrial myxoma

Infective endocarditis

Septal defects

Paradoxical emboli

21.4.2.2 Thrombosis

Retinal arterial occlusion may result from the development of a thrombosis within the vessel. This frequently occurs at a site of atherosclerosis. The rupture of an atherosclerotic plaque triggers platelet aggregation and thrombus formation. It is possible that most central retinal arterial occlusions are due to a thrombosis at the level of the lamina cribrosa. The risk factors are those common to cardiovascular disease in general: hypertension, smoking, hypercholesterolemia and diabetes.

21.4.2.3 Thrombophilia

Thrombophilia is a term referring to a diverse group of disorders that predispose an individual to the development of thrombosis. Many of these conditions have been reported in association with retinal arterial occlusion, usually in younger patients [57]. However, the true significance of these associations is difficult to evaluate as these coagulation abnormalities are found in the asymptomatic general population and so associations could have arisen by chance in some cases.

Thrombophilia can be either congenital or acquired. Congenital thrombophilic states are inherited disorders, which result in disturbance of the coagulation system either through increased levels of procoagulants, deficiencies of anticoagulants or reduced fibrinolysis. Acquired causes are a diverse group of conditions. In the antiphospholipid syndrome autoantibodies to phospholipids form immune complexes resulting in thrombosis formation. Hyperhomocysteinemia damages the vascular endothelium promoting thrombus formation. Hyperviscosity states such as myeloproliferative disorders and pregnancy have also been associated with retinal arterial occlusion.

Box 4: Congenital and acquired thrombophilia

Congenital thrombophilic states:

Factor V Leiden [9, 44, 71]

Prothrombin 20210 [9, 71] Protein C deficiency [49] Protein S deficiency [31] Antithrombin III deficiency [10]

Acquired thrombophilic states:

Antiphospholipid syndrome [21]

Hyperhomocysteinemia [19, 53]

Myeloproliferative disorders

Pregnancy

Oral contraceptive pill

21.4.2.4 Vasculitis

The systemic vasculitides are a group of conditions that produce inflammatory changes within the walls of blood vessels, leading to the obstruction of blood flow. Retinal arterial occlusions have been reported in association with a number of these disorders (Box 5). The most common of these is giant cell arteritis (temporal arteritis), which usually affects older people.

21.4.2.5 Infectious

A number of infectious conditions causing inflammatory problems in the retina can provoke occlusions of adjacent branch retinal arteries. These include toxoplasmosis, acute retinal necrosis, cat-

scratch disease and loiasis [11, 23, 24, 45, 61, 67, 77].

III 21

21.4.2.6 Other Causes

Retinal arterial occlusion has been reported in association with a number of medical procedures, including vitreoretinal surgery, arterial angiography, retrobulbar injections and neck manipulations [38]. Structural abnormalities of the eye such as optic disk drusen and pre-papillary arterial loops have been associated with central retinal artery occlusions (Fig. 21.4.1) [50]. Traumatic injury to the orbit and its contents can lead to vascular occlusion, sometimes associated with a retrobulbar hemorrhage [35]. Vasospasm induced by either migraines or cocaine use has been linked to retinal arterial occlusion in a number of younger patients [15, 70].

Box 5: Systemic vasculitis associated with retinal arterial occlusion

Giant cell arteritis Polyarteritis nodosa Wegner’s granulomatosis [52] Beh¸cet’s disease

Systemic lupus erythematosis Susac’s disease Dermatomyositis

a

Fig. 21.4.1. Pre-papillary loop resulting in an inferior hemiretinal arterial occlusion (a). The twisted loop is in the inferior division of the central retinal artery that lies anterior to the optic disk (b, c)

b

c

21.4.2.7Retinal Arterial Occlusion in the Young

Retinal arterial occlusion is a particularly rare event in younger people. Unlike older individuals they tend not to have atherosclerotic disease as the cause [32]. Instead a wide variety of underlying conditions

21 III have been reported including thrombophilic states, cardiac pathology, sickle cell disease, congenital abnormalities, trauma and migraine [15, 70].

21.4.3 Clinical Features

21.4.3.1 Anatomical Classification

The retinal arterial circulation can be obstructed at any point from the ophthalmic artery to the distal retinal arterioles (Box 6). The location of the obstruction determines the pattern of visual loss and clinical signs. The causes of the obstruction also vary by site with emboli being more commonly associated with branch (BRAO) rather than central retinal artery occlusion (CRAO).

Box 6: Sites of arterial obstruction

Ophthalmic artery

Central retinal artery

Branch retinal artery

Cilioretinal artery

Arterioles

21.4.3.2 History

Retinal arterial occlusion is characterized by a sudden, painless loss of vision. The visual defect is usually isolated to one eye and may be partial (BRAO and cilioretinal artery occlusion) or complete (CRAO and ophthalmic artery occlusion). Sometimes patients note the visual defect on waking up in the morning, which may be due to reduced retinal perfusion secondary to nocturnal hypotension. Some patients may report antecedent episodes of transient visual loss, amaurosis fugax. Patients who have giant cell arteritis as their underlying cause of arterial occlusion frequently have other symptoms such as temporal headache, jaw claudication, myalgia, weight loss and loss of appetite.

21.4.3.3 Examination

21.4.3.3.1 Ophthalmic Artery Occlusion

notype develops if there are concurrent multiple occlusions affecting both circulations [14, 41]. Patients may experience ocular pain. The vision is usually reduced to no perception of light with a dense relative afferent pupillary defect (RAPD). There is extensive whitening of the retina, which is more pronounced than a CRAO and usually no cherry red spot, as there is reduced perfusion of the choroid. Severe posterior segment neovascularization has been reported in some eyes following ophthalmic arterial occlusion [41].

21.4.3.3.2 Central Retinal Artery Occlusion

In a central retinal artery occlusion the blockage may occur at any point between the origin at the ophthalmic artery and the optic disk head, although most probably occur at the level of the lamina cribrosa. Vision is usually reduced to the level of counting fingers or hand movements, unless there is a separate cilioretinal artery supplying the macula [13, 43]. An RAPD is present. The retina may initially appear normal. Within a few hours the nerve fiber layer becomes thickened with retinal whitening particularly in the macula (Fig. 21.4.2). A cherry red spot develops at the fovea where the choroid is still visible. Emboli may be seen in the CRA in about a quarter of cases. Retinal arteries become thin and attenuated and may have breaks in the column of blood (boxcarring or cattle-trucking).

Over the course of several weeks the obstructed vessel may be recanalized allowing reperfusion of retinal vessels. The retinal edema resolves. The optic disk eventually becomes atrophic. Neovascularization of the iris occurs in 16 – 18 % of eyes with CRAO (Fig. 21.4.3), while new vessels at the optic disk are quite rare [27, 28].

Ophthalmic artery occlusion interrupts the blood supply to both the retina and the choroid, resulting in profound loss of vision. An identical clinical phe-

Fig. 21.4.2. Central retinal arterial occlusion. The retinal arteries are thin. The macula is pale with a cherry red spot at the center

21.4.3.3.3 Branch Retinal Artery Occlusion

Branch retinal artery occlusion tends to result in less severe visual loss than a CRAO (Fig. 21.4.4). Patients notice a partial loss of vision, often with an altitudinal visual field defect. An RAPD is usually present. The right eye is more commonly affected than the left, as cardiac emboli more readily travel up the right carotid artery. The temporal retina is more susceptible than the nasal [51]. Emboli are the cause of most BRAO. Visible emboli are found in up to 68 % of cases [75]. The retina is pale in the affected sector. Neovascularization is a rare complication of BRAO.

21.4.3.3.4 Cilioretinal Artery Occlusion

Cilioretinal arteries arise from the short posterior ciliary arteries and can be found in about 32 % of eyes [37]. There is marked variation in the number, size and distribution of these arteries. In about 19 % of eyes they contribute to the macula blood supply. These vessels fill just before the central retinal artery

on fluorescein angiography. In cases of CRAO the presence of an additional cilioretinal blood supply to the macula can help to preserve central vision (Fig. 21.4.5) [17].

The cilioretinal arteries can become occluded leading to visual impairment. Three distinct patterns of cilioretinal occlusion have been described [16]. In the first group the occlusion is isolated. This is often associated with carotid artery atherosclerotic disease and the visual outcome is usually good (90 % achieving 6/12). Secondly, cilioretinal artery occlusion can occur in eyes with central retinal vein occlusions (CRVO) [12, 16]. Various mechanisms may explain this association: back pressure in the cilioretinal arteries secondary to the CRVO, simultaneous reduction in perfusion pressure of the cilioretinal arteries and the retinal veins or a vasculitic process occurring in the optic disk. The third pattern of cilioretinal artery occlusion is associated with an anterior ischemic optic neuropathy, which has a very poor visual prognosis (usually less than 3/60).