Purpose
To investigate if cases of diabetic macular edema (DME) associated with serous macular detachment (SMD) have a different topographic profile of retinal thickening compared to DME cases that are not associated with SMD.
Methods
Optical Coherence Tomography (OCT) scans from a total of 152 eyes from 152 patients with center-involving DME and central subfield thickness > 350 µm, were identified from departmental imaging databases in three centers; Royal Wolverhampton Hospitals NHS Trust, UK, Moorfields Eye Hospital NHS Foundation Trust, UK and Singapore National Eye Centre, Singapore. Measurements were taken of retinal thickness at the fovea (H) and extent of retina thicker than 350µm (W). H/W ratio was used as an “index for diffuseness” with lower values indicating a more diffuse spread of edema. Group means were compared between eyes with SMD and eyes without SMD.
Results
SMD was present in 55 eyes (36%). H (retinal thickness at the fovea) was lower in eyes with SMD than in eyes without SMD (396 µm vs. 550 µm, p<0.001) while W (extent of retina thicker than 350µm) was higher in eyes with SMD compared to eyes without SMD (4.74 mm vs. 4.18 mm, p=0.011). Eyes with SMD had significantly lower values of H/W compared with eyes without SMD (97.37 vs. 153.35, p=0.007).
Conclusions
In DME, the OCT profiles of retinal thickening differed between eyes with SMD and eyes without SMD. These observations may be explained by differences in the amount of retinal tissue expansion due to edema in the planes parallel to and perpendicular to the retinal surface. Our findings suggest the possibility of two morphological subtypes in DME, one of which may be associated with a higher probability of SMD. Our work generates a hypothesis that axial compliance of the retina may be an independent factor affecting the likelihood of developing SMD in DME.
Keywords: 505 edema •
585 macula/fovea •
697 retinal detachment