Abstract
Purpose:
To determine the relationship between retinal thickness and choroid thickness, and to determine the difference in choroidal thickness in diabetics and non-diabetics.
Methods:
The choroidal thickness (CT) and retinal thickness (RT) were manually measured at the fovea, 500 μm, 1000μm, 1500μm, and 3000μm superior, nasal, inferior, and temporal to the fovea using the Heidlberg Enhanced Depth Imaging Optical Coherence Tomography (EDI OCT). A total of 34 measurements were obtained for each of the 36 eyes in the study (16 eyes with diabetic retinopathy (DR) and cystoid macular edema (CME), 4 eyes with DR but no CME, and 16 normals).
Results:
In eyes with diabetic macular edema, the Pearson correlation coefficient for choroidal and macular thickness at the fovea was r=0.39 (p=0.002); at 500μm from the fovea, r=0.063 (p=0.6); at 1000μm, r=-0.026 (p=0.85); at 1500μm; r=-0.20 (p=0.17); and at 3000μm, r=0.084 (p=0.55). In non-diabetics, the correlation at the fovea was r= -0.22 (p=0.11); at 500μm, r=-0.17 (p=0.20); at 1000μm, r=012 (p=0.40); at 1500μm, r=0.068 (p=0.62); and at 3000μm, r=-0.11 (p=0.40). The average choroidal thickness in diabetics was thinner than in non-diabetics (282μm vs. 369μm, respectively, p<0.001). At the fovea, the choroid was 329μm in diabetics and 396μm in controls (p=0.04) while the retinal thickness was 313μm in diabetics and 251 in controls (p=0.02). At 500μm from the fovea, the CT was 304μm in CME vs. 278μm in controls (p<0.001), and RT was 372μm vs. 329μm (p<0.001); at 1000μm, CT was 296μm vs. 399μm (p<0.001), respectively, and RT was 375μm vs. 355μm (p=0.11), respectively; at 1500μm, the CT was 289μm vs. 382 μm (p<0.001), and the RT was 341μm vs. 339μm (p=0.90); and at 3000μm, the CT was 233μm vs. 344μm (p<0.001), and the RT was 335μm vs. 287μm (p=0.04). There was no difference in choroid thickness between diabetics with and without CME (an average of 271μm in CME vs. 282μm in diabetics without CME, p=0.27).
Conclusions:
The choroidal thickness was correlated with retinal thickness at the fovea in diabetic cystoid macular edema, but the relationship was not linearly correlated outside the fovea. The choroid was thinner in diabetics compared to non-diabetics, and in all patients, the choroid was thickest at the fovea and decreased peripherally, regardless of the presence of macular edema.
Keywords: 452 choroid •
585 macula/fovea •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)