High-resolution Fourier-domain optical coherence tomography of choroidal neovascular membranes associated with age-related macular degeneration

Abstract

Purpose: To investigate the use of high-resolution Fourier-domain optical coherence tomography (Fd-OCT) to image choroidal neovascular membranes (CNVMs) associated with exudative age-related macular degeneration (eAMD).

Methods: An Fd-OCT instrument with axial resolution of 4 to 4.5 microm and transverse resolution of 10 to 15 microm was used to image 21 eyes (19 subjects) with newly diagnosed eAMD. A raster series of 100 B-scans separated by 60 microm was used to study the growth pattern of CNVM and associated morphologic changes. CNVM size was determined using 250 to 300 serial virtual C-scans of reconstructed three-dimensional macular volume.

Results: A highly reflective subretinal and/or subretinal pigment epithelial (RPE) lesion that co-localized with the CNVM seen on fluorescein angiography was detected in all eyes by Fd-OCT. Although a combined subretinal and sub-RPE growth pattern of various degrees was noted in 15 (71%) eyes, a statistically significant difference in the distribution of growth pattern was noted when classic CNVM was compared with occult CNVM (chi(2) = 10.4, df = 2, P < 0.005). Classic lesions had >90% subretinal growth pattern, whereas occult lesions had a more variable growth pattern. Angiographic CNVM size correlated with size on Fd-OCT but correlation was better for classic CNVM (classic, r = 0.99, P < 0.0001; nonclassic, r = 0.78, P < 0.001).

Conclusions: Fd-OCT is a promising potential alternative modality to visualize CNVM with AMD. Angiographic lesion size and type correlated with growth pattern and size of CNVM on Fd-OCT, with correlation being stronger for classic lesions.

Figure 1.

FA and high-resolution Fd-OCT of the right eye in case 17 with an occult CNVM associated with a PED from eAMD showing a predominantly subretinal growth pattern of CNVM. (A) Early-phase FA shows an ill-defined area of hyperfluorescence centered over the macula with an adjacent area of early pooling consistent with a PED. White line: the representative B-scan shown in Figure 2C. (B) Late-phase FA showing intense pooling into the PED, with ill-defined leakage at the superonasal edge. White line: the representative Fd-OCT B-scan shown in Figure 2C. (C) A representative Fd-OCT B-scan shows a large PED with an adjacent area of subretinal fluid. There is a highly reflective subretinal lesion above the PED, consistent with a type 2 (subretinal) CNVM. There is a focal spot of discontinuity in the RPE (*), with a possible small extension of the hyperreflectivity into the sub-RPE space. The lower image outlines the extent of the hyperreflective lesion. (D) Serial reconstructed C-scans were overlaid to measure the GLD of the CNVM (top image, line). Bottom: B-scans, with white lines representing the cut depicted by the C-scan shown above.

Figure 2.

Fluorescein angiogram and high-resolution Fd-OCT of the left eye in case 8 showing a mostly subretinal growth pattern of CNVM in an eye with a minimally classic angiographic lesion composition. (A) Early phase angiogram shows a well-defined juxtafoveal area of hyperfluorescence with rim of hypofluorescence and an adjacent area of faint mottled hyperfluorescence. White line: the representative B-scan shown in Figure 1C. (B) Late-phase FA showing leakage around the area of early well-defined hyperfluorescence and the adjacent area of mottled hyperfluorescence, consistent with a minimally classic CNVM. (C, top) A representative Fd-OCT B-scan selected out of a series of 100 B-scans shows a hyperreflective lesion mostly in the subretinal space, with a small sub-RPE component connected through a focal discontinuity in the RPE within the lesion. There are pockets of subretinal fluid on either side of the lesion, as well as a small PED. Bottom: the extent of the hyperreflective lesion is outlined in gray with the sub-RPE component of the lesion in a lighter shade.

Figure 3.

Linear regression analysis comparing the size of CNVM associated with eAMD as determined by high-resolution Fd-OCT when compared with FA. (A) Analysis of eyes with classic CNVM shows a close linear correlation between GLD of the CNVM obtained by Fd-OCT and that obtained by FA (r = 0.99, F_1,5 = 214.10, P < 0.0001, n = 7). (B) Analysis of eyes with nonclassic CNVM showing a less strong but significant correlation between GLD of the CNVM by Fd-OCT with GLD by FA (r = 0.78, F_1,12 = 18.44, P < 0.001, n = 14). The FA GLD was measured, and the Fd-OCT GLD was determined by examining serial reconstructed C-scan images.