Analysis of morphological features and vascular layers of choroid in diabetic retinopathy using spectral-domain optical coherence tomography

Abstract

Importance: Diabetic retinopathy (DR) is characterized by microaneurysms, capillary nonperfusion, and ischemia within the retina, ultimately leading to neovascularization and/or macular edema. Evidence suggests that choroidal angiopathy may coexist with retinal vascular damage. Recent advances in spectral-domain optical coherence tomography (SD-OCT) permit an efficient visualization of the choroid.

Objective: To analyze the morphological features and vascular layers of the choroid in patients with DR using SD-OCT.

Design: A cross-sectional retrospective review identified patients with DR and healthy (control) subjects who underwent 1-line raster scanning from February 1, 2010, through June 30, 2012. Patients were classified into the following 3 groups: nonproliferative DR without macular edema (9 eyes), proliferative DR without macular edema (PDR) (10 eyes), and diabetic macular edema (DME) (14 eyes). Two independent raters experienced in analyzing OCT images evaluated the morphological features and vasculature of the choroid.

Setting: New England Eye Center.

Participants: Thirty-three eyes of 33 patients with DR and 24 eyes of 24 controls.

Exposure: Diabetic retinopathy.

Main outcome and measure: Choroidal morphological features and vasculature analysis.

Results: The choroidoscleral interface had an irregular contour in 8 of 9 eyes with nonproliferative DR (89%), 9 of 10 eyes with PDR (90%), and 13 of 14 eyes with DME (93%) compared with 0 of 24 controls. The thickest point of the choroid was displaced from under the fovea, and focal choroidal thinning was observed in eyes with DR. Mean subfoveal choroidal thickness and mean subfoveal medium choroidal vessel layer and choriocapillaris layer thickness were significantly reduced in eyes with PDR (P < .05) and DME (P < .05) compared with controls.

Conclusions and relevance: Choroidal morphological features are altered in patients with moderate to severe DR. The subfoveal choroidal thickness and the subfoveal medium choroidal vessel layer and choriocapillaris layer thicknesses are significantly reduced in patients with PDR and DME. To our knowledge, this is the first study to analyze the morphological features and vasculature of the choroid in DR using SD-OCT. These findings may be clinically useful in predicting the progression of DR.

Figure 1. Representative Optical Coherence Tomography Images Showing the Shape of the Choroidoscleral Interface

A, A healthy eye has a convex or bowl shape to the choroidoscleral interface (red line). B, An eye with nonproliferative diabetic retinopathy has an irregular, concave-convex-concave or S shape to the choroidoscleral interface (red line).

Figure 2. Morphological Features of the Choroid in Healthy Eyes and Eyes With Diabetic Retinopathy (DR)

A, Representative optical coherence tomography (OCT) image of a healthy eye with a thinner choroid nasally, much thicker beneath the fovea (falling within 200μm beneath the foveal center, green box), and temporal thinning. Red line represents the bowl shaped or convex contour to the choroidoscleral interface. B, Representative OCT image of an eye with nonproliferative diabetic retinopathy has an irregular or concave-convex-concave or S shape to the choroidoscleral interface (red line). The thickest point of the choroid is subfoveal (green box). Areas of focal choroidal thinning are seen. C, Representative OCT image of an eye with proliferative DR. An irregular or S shape to the choroidoscleral interface (red line) is seen. The thickest point of the choroid is temporally located. The nasal region shows focal thinning. D, Representative OCT image of an eye with diabetic macular edema. An irregular or S shape to the choroidoscleral interface (red line) is seen. The thickest point of the choroid is temporally located. The nasal and temporal regions show focal thinning.

Figure 3. Illustration of the Method Used to Analyze the Vascular Layers of the Choroid

The optical coherence tomography image of a healthy eye shows analysis of the choroidal vascular layers beneath the fovea. Blue asterisk represents the large choroidal vessel seen in the closest proximity to the fovea, and closest to the choroidoscleral interface, which was used for the large choroidal vessel layer (LCVL) measurements in this case. CT indicates choroidal thickness.

Figure 4. Graph of the Mean Subfoveal Total Choroidal Thickness in Healthy Eyes and Eyes With Nonproliferative Diabetic Retinopathy (NPDR), Proliferative Diabetic Retinopathy (PDR), and Diabetic Macular Edema (DME)

We found significant thinning of the choroid in eyes with PDR and DME compared with healthy eyes. Error bars represent the SEM. P values represent the results of the Tukey multiple comparisons test.

Figure 5. Graphs of the Mean Subfoveal Choroidal Vessel Layer Thickness in Healthy Eyes and Eyes With Nonproliferative Diabetic Retinopathy (NPDR), Proliferative Diabetic Retinopathy (PDR), and Diabetic Macular Edema (DME)

A, Mean (error bars represent SEM) subfoveal large choroidal vessel layer thickness. We found no significant difference in the mean subfoveal large choroidal vessel layer thickness between any groups. P values represent the results of the Tukey multiple comparisons test. B, Mean (error bars represent SEM) combined subfoveal medium choroidal vessel layer and choriocapillaris layer thickness. A significant thinning of the mean subfoveal medium choroidal vessel layer and choriocapillaris layer thickness is seen in eyes with PDR and DME (but not in eyes with NPDR) compared with healthy eyes. P values represent the results of the Tukey multiple comparisons test.