Assessment of Choroidal Microstructure and Subfoveal Thickness Change in Eyes With Different Stages of Age-Related Macular Degeneration

Abstract

Age-related macular degeneration (AMD) is a major cause of irreversible blindness. Choroidal structural changes seem to be inevitable in AMD pathogenesis. Our study revealed associated choroidal microstructural changes in AMD eyes.The aim of the study was to compare choroidal microstructural changes in eyes with AMD of different stages.The study was a retrospective, cross-sectional case series.The participants comprised of 32 age-matched normal eyes as controls, and 26 fellow uninvolved eyes of intermediate/late AMD, 29 of early AMD, 28 of intermediate AMD, and 39 of late AMD.All subjects underwent comprehensive ophthalmologic examination. The choroid images, including subfoveal choroidal thickness, percentage of Sattler layer area, and en face images of the choroid, were obtained using spectral-domain optical coherence tomography.The main outcome measures were subfoveal choroidal thickness changes, percentage of Sattler layer area changes, and en face images of the choroid in AMD eyes.One hundred fifty-four eyes of 96 individuals with mean age of 67.1±9.2 years were included. The mean subfoveal choroidal thickness was 295.4 ± 56.8 μm in age-matched normal eyes, 306.7 ± 68.4 μm in fellow uninvolved eyes with AMD, 293.8 ± 80.4 μm in early AMD, 215.6 ± 80.4 μm in intermediate AMD, and 200.4 ± 66.6 μm in late AMD (F = 14.2, all P < 0.001). Choroidal thickness was greater in early AMD eyes than in intermediate/late AMD eyes (P < 0.001). Mean percentage of Sattler layer area in each group showed a similar tendency. Microstructure of the choroid showed reduced vascular density of Sattler layer areas in late AMD eyes compared with normal eyes.Decreasing subfoveal choroidal thickness and percentage of Sattler layer area were demonstrated in the progression of AMD. The choroidal change was related to atrophy of the microstructural changes of underlying capillaries and medium-sized vessels.

FIGURE 1

Representative choroidal B-scan image obtained from SD-OCT. Image shows manual segmentation of Sattler layer border and Haller layer (yellow line). SD-OCT = spectral-domain optical coherence tomography.

FIGURE 2

Box plots show differences in thickness of subfoveal choroid in 5 groups. Choroidal thickness in group 4 and group 5 were significantly lesser than in early AMD eyes (P < 0.001). AMD = age-related macular degeneration.

FIGURE 3

Box plots show differences in percentage of Sattler area (SA) in 4 groups. The mean percentage of SA in normal eye (G1) and fellow eye of immediate/late AMD (G2) and early AMD (G3) were significantly higher than the eye of intermediate AMD (G4). AMD = age-related macular degeneration.

FIGURE 4

Example of choroidal B-scan images obtained from SD-OCT showing the percentage area of Sattler layer (yellow area) decreased from group 1 to group 4. SD-OCT = spectral-domain optical coherence tomography.

FIGURE 5

En face EDI-OCT scans of 6 × 6 mm subfoveal region of the 60 μm below RPE/Brunch membrane 20 μm in depth in 5 groups. Images show the dense distribution of dark regions in group 1 (top left), increasing bright-spotted hyper-reflective melanocytes in SA in group 2 and group 3, absence of small vessels in group 4, and almost complete absence of SA, straight large lumen vessels of Haller layer area in group 5. EDI-OCT = enhanced-depth imaging optical coherence tomography.