Recent trends in choroidal & RPE imaging
Marwa Sami Sharaf;
Abstract
The choroid is important to support retinal and visual function as it supplies nutrients and oxygen to retinal pigment epithelial (RPE) cells and photoreceptors. Therefore, the choroid may play a role in the pathophysiology of many vision threatening retinal diseases such as age-related macular degeneration, central serous chorioretinopathy, choroidal detachments and choroidal tumours (ikuno et al 2009), (Jung et al 2012).
On the other hand, the retinal pigment epithelium’s (RPE) functions are to absorb scattered light to improve the optical quality, transepithelial transportation of nutrients and waste products from the blood side to the photoreceptor side and vice versa (Gupta et al 2014).
Despite their importance, the choroid and RPE are not easily accessed on clinical examination. The normal pigmentation of the choroid and overlying RPE usually impedes full-thickness visualization of the choroid and the retinal pigment epithelium by ophthalmoscopy, fundus photography, or conventional OCT (Ferrarra et al ,2010)
Summary
96
As for Age related macular degeneration, EDI-OCT and FFA are useful in detecting ARMD as well as its types whether dry or wet. EDI-OCT helps predicting the prognosis by revealing choroidal thinning in the diseased eye (Chung et al., 2011), (Leung and Rosen, 2014), (Spaide, 2003).
Also, FAF imaging can show changes in the concentration and distribution of RPE lipofuscin and hence establish the condition of RPE in patients with the different stages OF ARMD (Ruiz-Moreno et al., 2010).
Indocyanine green angiography visualizes choroidal neovessels beneath blood layers, exudates or RPE detachments (PEDs) (Hewick et al., 2004). OCT and fluorescein angiography are considered the gold standard for the diagnosis of CSCR; EDI-OCT can diagnose CSCR and measure the subfoveal choroidal thickness which reflects the degree of CSCR, while fundus fluorescein angiography is used to detect focal leakage sites (Siddiqui et al., 2008), (Ahn et al., 2013), (Hamzah et al., 2014).
ICG angiography may denote regional vascular hyperpermeability in CSCR (Miller, 2009).
Autofluorescence imaging may play a crucial role for the diagnosis of both acute and chronic stages of central serous chorioretinopathy and
Summary
97
differentiate between them, especially when fluorescein angiography is contraindicated (Dinc et al., 2011). In choroidal tumours, ultrasound can be used to detect and measure the thickness and extent of the tumour especially extraorbital extension in malignant tumours. However, using EDI-OCT is more accurate in detecting small tumours as well as measuring the thickness of the tumour (Shields et al., 2012).
EDI OCT is able as well to study the internal structure and extent (thickness and diameter) of choroidal tumors. Thus differentiating between choroidal nevus and melanoma and detecting choroidal metastasis and hemangioma (Natesh et al., 2010), (Say et al., 2011), (Bach et al., 2014).
Additionally, the widefield image of FFA can detect the small differences in size or shape. Also it offers a benefit in lesions that change quickly, such as cancerous lesions, since multiple follow-up examinations are needed (Kernt et al., 2010).
In ICGA, intrinsic tumour vessels were visible in most tumours with maximal benefits in imaging choroidal hemangioma (Maruko et al., 2011), (Kernt et al., 2013).
Summary
98
In addition, it was found that nearly 90% of the choroidal tumors showed at least 1 focus of increased autofluorescence signal in FAF (Gündüz et al., 2007).
Choroidal detachment is best diagnosed by ultrasound revealing thick, smooth, dome-shaped detachment or may reveal kissing detachments showing their contents whether hemorrhagic or serous (Sabherwal et al., 2014).
In the same way, ultrawide FFA can show the extension of the detachment (Shah et al., 2009).
Regarding congenital hypertrophy of retinal pigment epithelium, EDI-OCT can diagnose the disease showing normal choroid underlying CHRPE suggesting that this RPE lesion is unrelated to the choroid (Fung et al., 2014).
Moreover, FFA can differentiate a CHRPE from a choroidal naevus, while ICG angiography can delineate the borders of the CHRPE more carefully than fluorescein angiography (Giuffre, 2005) (Ober et al., 2009).
On the other hand, the retinal pigment epithelium’s (RPE) functions are to absorb scattered light to improve the optical quality, transepithelial transportation of nutrients and waste products from the blood side to the photoreceptor side and vice versa (Gupta et al 2014).
Despite their importance, the choroid and RPE are not easily accessed on clinical examination. The normal pigmentation of the choroid and overlying RPE usually impedes full-thickness visualization of the choroid and the retinal pigment epithelium by ophthalmoscopy, fundus photography, or conventional OCT (Ferrarra et al ,2010)
Summary
96
As for Age related macular degeneration, EDI-OCT and FFA are useful in detecting ARMD as well as its types whether dry or wet. EDI-OCT helps predicting the prognosis by revealing choroidal thinning in the diseased eye (Chung et al., 2011), (Leung and Rosen, 2014), (Spaide, 2003).
Also, FAF imaging can show changes in the concentration and distribution of RPE lipofuscin and hence establish the condition of RPE in patients with the different stages OF ARMD (Ruiz-Moreno et al., 2010).
Indocyanine green angiography visualizes choroidal neovessels beneath blood layers, exudates or RPE detachments (PEDs) (Hewick et al., 2004). OCT and fluorescein angiography are considered the gold standard for the diagnosis of CSCR; EDI-OCT can diagnose CSCR and measure the subfoveal choroidal thickness which reflects the degree of CSCR, while fundus fluorescein angiography is used to detect focal leakage sites (Siddiqui et al., 2008), (Ahn et al., 2013), (Hamzah et al., 2014).
ICG angiography may denote regional vascular hyperpermeability in CSCR (Miller, 2009).
Autofluorescence imaging may play a crucial role for the diagnosis of both acute and chronic stages of central serous chorioretinopathy and
Summary
97
differentiate between them, especially when fluorescein angiography is contraindicated (Dinc et al., 2011). In choroidal tumours, ultrasound can be used to detect and measure the thickness and extent of the tumour especially extraorbital extension in malignant tumours. However, using EDI-OCT is more accurate in detecting small tumours as well as measuring the thickness of the tumour (Shields et al., 2012).
EDI OCT is able as well to study the internal structure and extent (thickness and diameter) of choroidal tumors. Thus differentiating between choroidal nevus and melanoma and detecting choroidal metastasis and hemangioma (Natesh et al., 2010), (Say et al., 2011), (Bach et al., 2014).
Additionally, the widefield image of FFA can detect the small differences in size or shape. Also it offers a benefit in lesions that change quickly, such as cancerous lesions, since multiple follow-up examinations are needed (Kernt et al., 2010).
In ICGA, intrinsic tumour vessels were visible in most tumours with maximal benefits in imaging choroidal hemangioma (Maruko et al., 2011), (Kernt et al., 2013).
Summary
98
In addition, it was found that nearly 90% of the choroidal tumors showed at least 1 focus of increased autofluorescence signal in FAF (Gündüz et al., 2007).
Choroidal detachment is best diagnosed by ultrasound revealing thick, smooth, dome-shaped detachment or may reveal kissing detachments showing their contents whether hemorrhagic or serous (Sabherwal et al., 2014).
In the same way, ultrawide FFA can show the extension of the detachment (Shah et al., 2009).
Regarding congenital hypertrophy of retinal pigment epithelium, EDI-OCT can diagnose the disease showing normal choroid underlying CHRPE suggesting that this RPE lesion is unrelated to the choroid (Fung et al., 2014).
Moreover, FFA can differentiate a CHRPE from a choroidal naevus, while ICG angiography can delineate the borders of the CHRPE more carefully than fluorescein angiography (Giuffre, 2005) (Ober et al., 2009).
Other data
| Title | Recent trends in choroidal & RPE imaging | Other Titles | الاتجاهات الحديثة فى تصوير المشيمية وطبقة ظهارة الخلايا الصبغية الشبكية | Authors | Marwa Sami Sharaf | Issue Date | 2015 |
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