BASICS

DESCRIPTION

• Choroidal neovascularization (CNV) is the development of new blood vessels from the choroid layer through a dehiscence or disturbance in Bruch’s membrane into the subretinal space.

• Choroidal neovascularization is often accompanied by fibroblasts. The resulting fibrovascular complex is unstable and can frequently leak serous fluid, hemorrhage, and result in a disciform scar.

• Multiple disorders that affect the retinal pigment epithelium (RPE)-Bruch’s membrane-choriocapillaris complex can cause choroidal neovascularization.

– Over 40 disease processes are associated with choroidal neovascularization with age-related macular degeneration (AMD), angioid streaks, pathologic myopia, ocular histoplasmosis syndrome, and blunt trauma being the commonest.

EPIDEMIOLOGY

Incidence

• Varies by underlying diagnosis

– Choroidal neovascularization associated with age-related macular degeneration is the leading cause of permanent visual loss in people over 65 years of age in developed countries.

Advanced AMD affects 25–30 million people worldwide and 1.75 million in the US.

Prevalence

• Varies by underlying diagnosis

– In AMD, the prevalence of choroidal neovascularization is primarily influenced by advancing age.

RISK FACTORS

• Varies by underlying diagnosis

– In AMD, advancing age is an obvious risk factor. Other factors include strong family history of AMD, race (more common in whites and Hispanics than blacks), cigarette smoking, hypertension, hyperlipidemia, abdominal obesity, reduced physical activity, and high dietary fat intake.

Genetics

• Varies by underlying diagnosis

– AMD –and its most severe complication, choroidal neovascularization– is recognized as resulting from a convergence of multiple risk factors. Family history is a consistent risk factor. Twin studies support a genetic basis for the disease with both early and late-onset findings (CNV) being approximately twice as high in monozygotic as dizygotic twins.

Genome-wide linkage analyses have identified a number of chromosomal loci linked to AMD.

GENERAL PREVENTION

• Avoid modifiable risk factors

• Nutritional supplementation has been shown to reduce the risk of progression of AMD to its more severe “wet” form in which there is development of CNV.

– The Age-related Eye Disease Study (AREDS) recommended the following: 500 mg vitamin C, 400 IU vitamin E, 15 mg beta-carotene, 80 mg zinc as zinc oxide, 2 mg copper as cupric oxide (the latter to prevent copper deficiency anemia associated with high levels of zinc intake).

AREDS II, currently underway, is assessing supplementation with micronutrients lutein, zeaxanthin, and omega-3 fatty acids (DHA and EPA).

PATHOPHYSIOLOGY

• Any disturbance of Bruch’s membrane, such as blunt trauma, an infectious process, or the non-neovascular abnormalities of AMD (drusen, RPE atrophy) can allow buds of neovascular tissue from the choriocapillaris to perforate the outer aspect of Bruch’s membrane.

– Once the stage is set for CNV, proangiogenic factors including vascular endothelial growth factor (VEGF), advanced glycosylation end-products (AGEs), platelet-derived growth factor (PDGF), and pigment epithelium-derived factor facilitate continued growth of CNV.

ETIOLOGY

Degenerative, infectious, traumatic, and genetically-determined disruptions of Bruch’s membrane

COMMONLY ASSOCIATED CONDITIONS

Age-related macular degeneration, angioid streaks, pathologic myopia, ocular histoplasmosis syndrome, blunt trauma/choroidal rupture, and multifocal choroiditis.

DIAGNOSIS

HISTORY

Sudden onset of decreased vision with metamorphopsia, and paracentral scotoma

PHYSICAL EXAM

Elevation of the RPE, serous subretinal fluid, intraretinal lipid, subretinal or less commonly intraretinal hemorrhage, RPE detachment, RPE rip, gray–green CNV lesion seen through retina.

DIAGNOSTIC TESTS & INTERPRETATION

Imaging

Initial approach

• Fluorescein angiography

– Various patterns may be seen including a classic CNV and occult CNV

– Blood may block CNV

Follow-up & special considerations

Treatment can be monitored with serial fluorescein angiography and optical coherence tomography.

Diagnostic Procedures/Other

• Optical coherence tomography (OCT)

– CNV appears as increased reflectivity deep to the retina

Secondary findings on OCT include RPE detachment, subretinal fluid, and intraretinal edema.

Pathological Findings

• New blood vessel growth from the choroid through Bruch’s membrane into the subretinal space

– In AMD, 3 growth patterns of CNV have been identified based upon the relationship of the CNV to the RPE

Type 1: CNV beneath the RPE

Type 2: CNV through RPE into subretinal space

Combined pattern of type 1 & 2

DIFFERENTIAL DIAGNOSIS

Retinal arteriolar macroaneurysm, central serous chorioretinopathy, Best’s disease, adult vitelliform dystrophy, polypoidal choroidal vasculopathy, posterior scleritis, multifocal choroiditis/inflammatory conditions, and choroidal hemangioma.

TREATMENT

MEDICATION

First Line

• In AMD, anti-VEGF drugs have become the standard of care in treating CNV. Ranibizumab and bevacizumab are the most frequently used.

• CNV outside the central macula (extrafoveal), especially when associated with disorders other that AMD (such as blunt trauma) may be treated with laser photocoagulation (thermal laser).

Second Line

• Photodynamic therapy (PDT – administration of a photosensitizing drug, verteporfin, followed by application of laser at the appropriate wavelength)

– The use of PDT has been largely supplanted by anti-VEGF therapy but still has a place in the management of CNV.

ADDITIONAL TREATMENT

General Measures

Low vision evaluation and prescription of aids, especially when CNV is bilateral.

Issues for Referral

New onset of decreased vision.

SURGERY/OTHER PROCEDURES

• Vitrectomy for evacuation of submacular hemorrhage from a ruptured CNV membrane may be considered.

– Vitrectomy for removal of CNV membranes is not useful in AMD patients, especially since anti-VEGF agents have become available.

Vitrectomy for removal of CNV membranes where the etiology is trauma or inflammation can still be considered.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

CNV may recur, so patients should be followed until complete stabilization has occurred.

Patient Monitoring

Amsler grid

DIET

AMD patients should eat a balanced diet low in high dietary fat and consider eating fish twice a week.

PROGNOSIS

Prognosis depends on location of CNV and whether or not hemorrhaging from the CNV has occurred.

COMPLICATIONS

Rarely massive subretinal hemorrhage can lead to a hemorrhagic retinal detachment and loss of all vision.

ADDITIONAL READING

• Do DV. Antiangiogenic approaches to age-related macular degeneration in the future. Ophthalmology 2009;116(10 Suppl):S24–26.

• Bressler NM. Antiangiogenic approaches to age-related macular degeneration in the future. Ophthalmology 2009;116(10 Suppl):S15–23.

• Cohen SY. Anti-VEGF drugs as the 2009 first-line therapy for choroidal neovascularization in pathologic myopia. Retina 2009;29(8):1062–1026.

CODES

ICD9

362.16 Retinal neovascularization nos

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