The role of spectral-domain OCT in the diagnosis and management of neovascular age-related macular degeneration

Abstract

Spectral-domain optical coherence tomography (SD-OCT) has emerged as the ancillary examination of choice to assist the diagnosis and management of neovascular age-related macular degeneration (AMD). SD-OCT provides more detailed images of intraretinal, subretinal, and subretinal pigment epithelium fluid when compared to time-domain technology, leading to higher and earlier detection rates of neovascular AMD activity. Improvements in image analysis and acquisition speed make it important for decision-making in the diagnosis and treatment of this disease. However, this new technology needs to be validated for its role in the improvement of visual outcomes in the context of anti-angiogenic therapy.

Figure 1

(A) Cross-sectional Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) image of the normal macula. (B) An enlargement of the image demonstrates the ability to visualize intraretinal layers that can be correlated with intraretinal anatomy: nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), external limiting membrane (ELM), junction of inner and outer photoreceptor segments (IS/OS), retinal pigment epithelium (RPE), and Bruch's membrane (BM).

Figure 2

Cross-sectional optical coherence tomography (OCT) images showing different types of choroidal neovascularization (CNV). (A) Cross-sectional image captured by RTVue (Optovue, Inc., Fremont, CA) showing a classic CNV, type 2 neovascularization, delineated as a nonuniform moderately hyperreflective formation above the RPE (green *) and the presence of intraretinal cysts (green open arrowhead). (B) Cross-sectional image captured by Heidelberg Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany) showing a fibrovascular pigment epithelial detachment, type 1 neovascularization (green *), and the presence of subretinal fluid (green closed arrowhead).

Figure 3

Occult choroidal neovascularization membrane. (A) The fluorescein angiogram performed in Heidelberg Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany) showed a speckled hyperfluorescence with dye pooled in the subretinal space on the late phase of the examination. (B) Cross-sectional image of Spectralis device depicted the thickened retinal pigment epithelium raised by non-uniform moderate hyperreflective formation with the presence of subretinal fluid (green closed arrowhead) and intraretinal fluid (green open arrowhead).

Figure 4

Type 3 neovascularization (retinal angiomatous proliferation). (A) Color photography showing intraretinal hemorrhage (green arrow). (B and C) Fluorescein angiograms show poorly defined hyperfluorescence typical of retinal angiomatous proliferation (green arrow). (D) An enlarged cross-sectional Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) image showing a pigment epithelium detachment and a vessel penetrating the retina (green arrow). (E) Cross-sectional Cirrus HD-OCT image showing a pigment epithelial detachment, a hyperreflective material (green arrow) that can be the neovascular tissue, in the outer retina layers. (F) Three-dimensional Cirrus HD-OCT image showing a hyperreflective material in the outer retina layers (black arrow).

Figure 5

Cross-sectional Cirrus HD-OCT (Carl Zeiss Meditec, Inc., Dublin, CA) image of a fibrovascular pigment epithelium detachment (PED) before and after retinal pigment epithelium (RPE) rip. (A) Cross-sectional image before rip. Note dome-shaped PED (green closed arrowhead) and intact RPE layer. (B) Cross-sectional image after rip. Arrow denotes discontinuity of the RPE layer. Note RPE scrolling at the edge of the RPE defect and pleating RPE over the PED (green closed arrowhead).

Figure 6

Sequential spectral-domain optical coherence tomography (OCT) scans of a 75-year-old woman with subfoveal choroidal neovascularization (CNV). A baseline scan depicted an elevation of the retinal pigment epithelium (RPE) layer, a localized fusiform thickening and duplication of the highly reflective external band (RPE/choriocapillaris complex), and intraretinal fluid corresponding to CNV. The patient was treated with intravitreous injection of ranibizumab at baseline, month 1, and month 2. Three months after the first injection, the OCT scan demonstrated improvement of macular architecture with mild intraretinal fluid. Additionally, the thickness map showed a signifi-cant decrease in the retinal thickness at the macular region. Between 3 and 12 months after treatment, three injections were administered due to the presence of discrete intraretinal fluid. It is important to note the better resolution of the 12-month scan due to image oversampling. The improvement in the resolution leads to a better visualization of retinal layers and it is possible to note the inner/outer segment junction interruption. At 15 months from the first injection, the patient presented intraretinal fluid and was treated with intravitreous ranibizumab. At 18 months of follow-up, no fluid was detected in the macular area, but the thickness map showed a diffuse thinning.

Figure 7

High pixel density high-speed ultra-high-resolution optical coherence tomography image from occult choroidal neovascularization. Note discontinuity of the inner/outer segment (IS/OS) junction line, subretinal fluid (white *), and pigment epithelium detachment. Bruch's membrane is demonstrated with the white arrowheads. RPE = retinal pigment epithelium.