Dr. Sangeet Mittal, M09477
Subretinal neovascular membrane (SRNVM) can complicate chronic central serous chorioretinopathy (CSR) and may be difficult to diagnose because CSR itself can be associated with pigment epithelial detachment, subretinal fluid and ill-defined patterns of hyperfluorescence on fundus fluorescein angiography (FFA) 1,2
Typical Classic SRNVM is characterized by well-demarcated areas of intense hyperfluorescence appearing early and showing progressive leakage. The fluorescein tends to be most intense at the periphery of the CNV; the center may show hypofluorescence. Leakage progresses into the late phase of the angiogram, and usually obscures the boundaries of the SRNVM. Classic description of visible subretinal vascular network (a lacy network) is seen in a minority of eyes with AMD.(3)
Structural optical coherence tomographic (OCT) techniques such as en face OCT have been used to identify SRNVM but the vascular contrast is low, limiting image detail.(4)
OCT angiography is a non invasive imaging technique which enables distinct, depth resolved, three dimensional visualization of the chorio capillaries and retinal microvasculature by combining vascular flow detection and structural information. It uses motion contrast instead of intravenous dye to analyze retinal blood flow .(5)
OCT Angiography was performed in 21 consecutive patients referred to the retina clinic for management of CSCR. The diagnosis of CSCR had been made by the referring ophthalmologist after clinical examination and FFA. FFA in all these patients showed ink blot pattern of leakage of dye, typical of CSCR. OCT Angiography was done in these eyes using commercially available RTVue XR Avanti with Angiovue. OCTA images were automatically segmented to inner capillaries, outer capillaries, outer retina and choriocapilaries segments.
In 3 eyes(14.2%), outer retina segment on OCT Angiography, which otherwise should be avascular, revealed a vascular shadow corresponding to the hot spot in the FFA. In one eye, a corresponding lesion was also seen in chorio-capilaries segment. In 18 eyes there was no such shadow in the region of hot spot. One of these 3 patients underwent Intravitreal Injection of Bevacizumab in the affected eye. The vascular shadow decreased one day after the intravitreal injection suggestive pf presence of CNVM.
Optical coherence tomographic angiography provides a novel way to potentially detect SRNVM. (6) In these 3 cases, OCT angiography identified SRNVM associated with CSR, while findings on structural OCT and FFA were non diagnostic. Because OCT angiography detects SRNVM by depth (flow in outer retina), it is not dependent on specific dye leakage patterns. Future studies with OCT angiography may reveal higher rates of SRNVM associated with chronic CSR than previously suspected. Bonini et al( 7) have showed an agreement between OCTA and dye based angiography. OCTA alone may be a viable alternative to dye based angiography in the diagnosis of SRNVM s in CSR patients and contribute to unequivocal diagnosis.
1 Fung AT, Yannuzzi LA, Freund KB. Type 1 (sub-retinal pigment epithelial) neovascularization in central serous chorioretinopathy masquerading as neovascular age-related macular degeneration. Retina. 2012;32(9):1829-1837.
2 Spaide RF, Campeas L, Haas A, et al. Central serous chorioretinopathy in younger and older adults. Ophthalmology. 1996;103(12):2070-2079.
3 Review of ophthalmology Amitha Domalpally, MD and Ronald P. Danis, MD, Madison
4.Ferrara D, Mohler KJ, Waheed N, et al. En face enhanced-depth swept-source optical coherence tomography features of chronic central serous chorioretinopathy. Ophthalmology. 2014;121(3):719-726.
5 Retinal Physician OCT Angiography eUpdate Jay S. Duker,MD,Marco Antonio Bonini Filho,MD,PhD
6 Jia Y, Bailey ST, Wilson DJ, et al. Quantitative optical coherence tomography angiography of choroidal neovascularization in age-related macular degeneration. Ophthalmology. 2014;121(7):1435-1444. |
7 Bonini Filho MA ,de CarloTE, Ferrara D ,et al .Association of choroidal neovascularization and central serous chorioretinopathy with optical coherence tomography.JAMA Ophthalmol.2015;133(8);899-906