Matthew R. Debiec

BASICS

DESCRIPTION

Irregular crack-like dehiscences in Bruch’s membrane that can be associated with multiple systemic conditions. Significant sequelae include subretinal hemorrhage, choroidal rupture, and possible choroidal neovascularization (CNV).

EPIDEMIOLOGY

Incidence

• Incidence of angioid streaks is based on the underlying condition. Pseudoxanthoma elasticum (PXE), the most common underlying condition, has an incidence of 1 in 160,000.

– Typically develops between the second and fifth decade of life.

Prevalence

Variable based on the underlying condition. Approximately one-third to half of cases have been reported to occur in patients with PXE. Of patients with PXE, more than 80% tend to have angioid streaks. Approximately 15% of patients with Paget’s disease of bone and anywhere from 1–20% of patients with sickle-cell disease develop angioid streaks.

RISK FACTORS

• The most common diseases related to angioid streaks are pseudoxanthoma elasticum, Paget’s disease of bone, sickle-cell anemia, and Ehlers-Danlos.

• Other diseases include:

– Acquired hemochromatosis

– Acromegaly

– Diabetes mellitus

– Acquired hemolytic anemia

– Hereditary spherocytosis

– Myopia

– Neurofibromatosis

– Sturge-Weber syndrome

– Hyperphosphatemia

– Senile elastosis

– Tuberous sclerosis

– Some patients have no identifiable systemic disease that can be attributed to angioid streaks and are considered to develop them idiopathically.

Genetics

• Varies based on the underlying condition causing angioid streaks.

– Pseudoxanthoma elasticum, the most common associated condition, is due to an autosomal recessive or dominant mutation in the ABCC6 transporter gene.

GENERAL PREVENTION

• There are no treatments known to prevent angioid streaks in patients who may be at risk; some reports indicated increased complications following prophylactic laser therapy.

• Patients are susceptible to choroidal rupture following mild trauma and should be educated to wear protective eyewear.

PATHOPHYSIOLOGY

• The crack-like dehiscences are produced by alterations in Bruch’s membrane, making it more prone to cracks. Full thickness breaks may allow CNV membranes to form.

• Subretinal hemorrhages can develop regardless of the presence of a CNV. Subretinal hemorrhage can follow traumatic breaks in Bruch’s membrane and can disseminate toward the macula.

ETIOLOGY

Underlying genetic predisposition of the aforementioned conditions combined with possible unknown environmental or acquired risk factors lead to angioid streaks.

COMMONLY ASSOCIATED CONDITIONS

See risk factors above.

DIAGNOSIS

HISTORY

Angioid streaks are typically asymptomatic although they can present with metamorphopsia and decreased vision.

PHYSICAL EXAM

• Diagnosis is typically based on the characteristic funduscopic appearance, although imaging such as FA or ICG aid in diagnosis.

• Angioid streaks appear on exam as narrow jagged lines, deep to the retina, that radiate out from areas of peripapillary pigment alterations.

• The streaks are almost always bilateral and usually occur in the posterior pole. Width ranges from 50–500 μm. The color of the streaks varies and may range from dark red to brown.

• Eyes of patients with PXE may demonstrate peau d’orange, which is diffused mottling of the retinal pigmented epithelium (RPE) typically found temporal to the macula. These patients may also develop yellowish spots described as salmon spots at the level of the RPE.

• A choroidal neovascular membrane may develop at sites of angioid streaks and full thickness breaks in Bruch’s membrane.

• Over two-thirds of patients with angioid streaks develop CNV at some point; however, this rate varies greatly depending on the clinical condition. While patients with PXE have the relative highest probability of macular CNV, patients with sickle-cell anemia tend to have a substantially lower rate of CNV.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• Laboratory work-up tends to center around evaluating for systemic conditions in those patients that do not have a predisposing diagnosis.

• A focused medical work up may include: Skin biopsy, x-ray imaging, hemoglobin electrophoresis, genetic testing, or blood work.

Imaging

Initial approach

• Fluorescein angiography (FA) is not necessary for diagnosis, but is extremely helpful in establishing the diagnosis in early streaks adjacent to the optic disc and in evaluating the development of CNV.

– Angioid streaks will appear hyperfluorescent (window defect) in the early phase of FA.

– CNV shows early hyperfluorescence and late staining.

• Indocyanine Green (ICG) angiography may be employed when both funduscopy and FA are equivocal, for example, in cases of extensive hemorrhages or severe RPE lesions. ICG angiography may show hyperfluorescent lines with pinpoints over their length.

Follow-up & special considerations

Patients with angioid streaks may require on-going follow up with FA to assess for development of CNV.

Pathological Findings

• Characteristic findings include irregular crack-like dehiscences in Bruch’s membrane with atrophic degeneration of the overlying RPE.

• Eyes with angioid streaks have shown extensive calcification and thickening of Bruch’s membrane with PXE and Paget’s disease of bone, although this is not always found in other associated conditions. Bruch’s membrane in Sickle hemoglobinopathies has demonstrated iron deposition in addition to calcification.

• The elastic lamina in the middle of Bruch’s membrane is often affected with disintegration and fraying of the elastic fibers.

DIFFERENTIAL DIAGNOSIS

• Age-related macular degeneration

• Pathologic myopia

• Histoplasmosis

• Toxoplasmosis

• Retinal vasculitis

• Choroidal rupture

TREATMENT

MEDICATION

First Line

• More recently, off-label use of anti-vascular endothelial growth factor therapy such as pegaptanib, ranibizumab, and bevacizumab has been used to treat CNV.

– Short-term studies have shown favorable results.

– One study examining results of bevacizumab up to 24 months after initiation of therapy found recurrence of CNV in up to one-third of patients and new CNV lesions in 20% of patients.

• Risk of intravitreal injections in these eyes is not fully known.

ADDITIONAL TREATMENT

General Measures

• Laser photocoagulation to CNV lesions in patients with angioid streaks has modest results. Argon or Krypton laser photocoagulation is typically considered in eyes with extrafoveal or juxtafoveal CNV. Findings typically show moderate visual loss in eyes treated with laser photocoagulation and greater than 50% rate of persistence and/or recurrence. However, eyes with angioid streaks that are untreated and allowed to naturally progress have a very high rate of poor visual outcome, often with visual acuities of 20/200 or worse.

– Prophylactic therapy of angioid streaks may actually induce more rapid progression to development of CNV.

• Photodynamic therapy (PDT) with verteporfin may be considered for eyes with subfoveal CNV. This therapy has been attempted in some small retrospective and prospective studies although benefit is limited to a short period and it is often associated with recurrence or subsequent chorioretinal atrophy. Several studies show contradictory results and many consider it as a method to slow, but not prevent the natural course of CNV in angioid streaks.

SURGERY/OTHER PROCEDURES

Macular translocation and submacular surgery has been previously attempted in rare cases of angioid streaks with variable success.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• Patients with angioid streaks should have examinations at least every 6 months to assess for the development of CNV given its relatively high incidence. This follow-up may include FA to assess for CNV.

• Development of symptoms should prompt increased frequency of evaluation to at least every 3 months.

– Patients that have recently been treated with laser and/or anti-VEGF therapy should be evaluated regularly.

• Patients can be instructed in the use of Amsler grid testing for home monitoring.

PATIENT EDUCATION

Patients should be educated about the importance of protective eyewear as the chance of choroidal rupture or subretinal hemorrhage is high with even minor trauma.

PROGNOSIS

Visual prognosis of eyes with angioid streaks is poor, although this varies based on the underlying diagnosis, time of onset of symptoms, and response to various types of therapy. It appears that in the natural history of untreated eyes, most end up with visual acuity of 20/200 or worse. At present, therapy is directed toward slowing the rate of visual loss and CNV progression.

COMPLICATIONS

Patients with angioid streaks and Pseudoxanthoma Elasticum are at increased risk for cardiovascular disease and spontaneous gastrointestinal bleeding.

ADDITIONAL READING

• Clarkson J, Altman R. Angioid streaks. Surv Ophthalmol 1982; 26(5): 235–246.

• Sawa M, Gomi F, Tsujikawa M, et al. Long-term results of intravitreal bevacizumab injection for choroidal neovascularization secondary to angioid streaks. Am J Ophthalmol 2009; 148(4): 584–590.

• Lim J, Bressler N, Marsh M, et al. Laser treatment of choroidal neovascularization in patients with angioid streaks. Am J Ophthalmol 1993; 116: 414–423.

• Georgalas I, Papaconstantinou D, Koutsandrea C, et al. Angioid streaks, clinical course, complications, and current therapeutic management. Ther Clin Risk Manag 2009; 5(1): 81–89.

• Gurwood A, Mastrangelo D. Understanding angioid streaks. J Am Optometric Assoc 1997; 68(5): 309–324.

CODES

ICD9

363.43 Angioid streaks of choroid

CLINICAL PEARLS

• Angioid streaks may be a sign of an underlying disease such as pseudoxanthoma elasticum, Ehlers-Danlos syndrome, sickle-cell hemoglobinopathy, or Paget’s disease of bone. It may also be idiopathic.

• Angioid streaks make the eye susceptible to severe subretinal hemorrhages from even minor blunt trauma, so patients should wear eye protection at all time.

• Choroidal neovascularization may develop in the areas of angioid streaks; patients need to self-monitor their vision and have regular fundus exams.

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