Background: The introduction of optical coherence tomography (OCT) has brought new potentialities for an objective evaluation of macular diseases. The purpose of the present study was to assess the serous macular detachment (SMD) in eyes with diabetic macular edema (DME) by use of spectral-domain OCT.
Methods: In this prospective study were included 79 eyes of 46 patients with diabetic retinopathy and DME. All patients underwent examination of best-corrected visual acuity (BCVA), non-contact slit-lamp fundus biomicroscopy, fluorescein angiography and OCT. Spectral-domain OCT (OCT/SLO Combination Imaging System, OPKO/OT Inc., Toronto, Ontario, Canada) was used to evaluate retinal morphology and the presence of macular traction (vitreomacular and/or from epiretinal membranes) on B-scans, C-scans and C-scan OCT/SLO fundus image overlays. With OCT were measured retinal thickness, volume, diameter of intraretinal cystoid spaces, diameter and height of SMD. The correlation of retinal thickness and volume with BCVA in all eyes with DME and the relation of SMD to retinal thickness, volume, BCVA, macular traction and ischemia were assessed.
Results: The SMD was diagnosed only by means of OCT in nine eyes (11.4%) of five patients. In eight of nine eyes it was combined with intermediate (300-600 microm) or severe (>600 microm) cystoid spaces, and in one eye with simple macular edema. Retinal thickness and volume correlated with BCVA (r = 0.464, P < 0.0001 and r = 0.480, P < 0.0001). The SMD height did not correlate with retinal thickness, volume or BCVA. Six eyes with SMD had macular ischemia, and five eyes had severe ischemia in retinal periphery. Macular traction was: absent in three eyes, questionable (without distortion of retinal contour from partial posterior vitreous detachment and/or epiretinal membrane) in three eyes, and definite (with distortion of retinal contour) in three eyes.
Conclusions: Spectral-domain OCT provided valuable information on retinal morphology and was particularly useful in diagnosing sub-clinical SMD in eyes with DME. It disclosed the presence and strength of macular traction either by partially detached posterior hyaloid or by epiretinal membranes. C-scans and C-scan OCT/SLO fundus image overlays added complementary information for the extent and location of the pathological features. Larger studies which follow subjects longitudinally are needed to explain the pathogenesis and determine the prognosis of SMD.