Choroidal Neovascular Membranes Workup

Updated: Mar 01, 2017
  • Author: Steve Charles, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Workup

Laboratory Studies

No laboratory tests exist for most diseases associated with choroidal neovascular membranes (CNVMs).

Hereditary macular degeneration can usually be identified from clinical presentation, family history, angiography, electroretinogram (ERG), [41] electro-oculogram (EOG), [42] psychophysical testing (eg, color vision, perimetry, dark adaptation), and genetic testing.

The diagnosis of histoplasmosis is based on fundus findings not serologic or skin testing.

Angioid streaks are usually due to pseudoxanthoma elasticum (PXE), but they have also been reported in patients with sickle cell disease and Paget disease.

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Imaging Studies

FA and ICG angiography were historically used in confirming the diagnosis, in determining the efficacy of treatment, in determining the need for retreatment, and, rarely, in guiding laser and photodynamic therapy (PDT). [43, 44, 45, 46, 47, 48, 49] However, OCT imaging has largely replaced angiography.

Digital angiography offers the advantages of immediate viewing, local area network (LAN) and/or wide area network (WAN) access, archiving, and incorporation into the computerized medical record, but it offers no better resolution than film-based imaging. Confocal laser scanning-based imaging dramatically improves the signal to background ratio by 15 dB, provides better illumination of the fluorophore, and improves image quality as compared to a fundus camera-based digital imaging system.

ICG angiography is rarely needed. Retinal angiomatous proliferation (RAP) is relatively common and is best visualized with confocal angiography; however, careful contact lens examination is often sufficient.

Ocular coherence tomography has become an essential tool both in performing the initial workup and in determining the need for treatment and retreatment of patients with CNVMs. [50] The initial technology was based on time domain OCT (Zeiss Stratus III), which served the vitreoretinal community well; however, the recent transition to spectral domain OCT provides far better axial and lateral resolution. [51] It is routinely possible to identify the CNVM, not just the presence of subretinal fluid, PED, and overlying retinal edema. Swept source OCT imaging may prove to be somewhat better than spectral domain OCT imaging. OCT angiography has not been shown to be of value, although there is substantial marketing pressure.

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Histologic Findings

Biopsy is not performed in CNVM cases. If submacular surgery is performed for non-AMD cases in very rare instances, histology is not needed, as many of these lesions have been studied; histology is of no value to the patient. [52, 53]

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