Abstract
Purpose: :
To evaluate whether specific morphologic characteristics can be defined to distinguish cystoid macular edema (CME) of different origins by SD-OCT
Methods: :
85 eyes with CME were included; 29 with untreated CME due to uveitis (uvCME), 24 with treatment-naive branch retinal vein occlusion (BRVO) and 32 with (at least 3 months untreated) diabetic macular edema (DME). Fourteen healthy subjects formed the control group. HD-OCT central line (horizontal/ vertical) and section scans were performed using Spectralis OCT. Scans were graded by two independent masked readers for CME-pattern in every particular ETDRS subgrid, CME distribution,-symmetry, layer cyst-location, subretinal detachment (SRD), epiretinal membrane (ERM), intraretinal blood, microaneurysms, cotton wool spots (CWS), microfoci, hard exudates, hyperreflective SRD deposits, preserved foveal depression, integrity and individual layer thicknesses (measured central, foveal, parafoveal and extrafoveal) and retinal thickness.
Results: :
UvCME showed the thickest inner nuclear layer (INL), DME the thickest outer nuclear layer (ONL) and BRVO the thickest ganglion cell layer. Cysts restricted to the INL defined uvCME, cysts restricted to the ONL defined DME, whereas cysts in BRVO were never confined to a single layer. UvCME showed a symmetric, central distribution with the cyst maximum in the central subfield, unless an ERM was present. BRVO manifested with hemi (= generalized CME either only nasal or temporal) or generalized edema, asymmetric distribution and a cone shaped CME pattern in the EDTRS grid with CME maximum in the inner superior or inferior subgrid. Diffuse and focal CME were specific for DME (DME:42%,others:0%). Preserved foveal depression (DME:64%,BRVO:30%,uvCME:24%), microaneurysms in INL (DME:97%,others:0%), microfoci (DME:97%,BRVO:65%,uvCME:0%) and hard exudates (DME:81%,BRVO:13%, uvCME:0%) were indicatory for DME, CWS (BRVO:88%,DME:6%, uvCME:0%), widespread shadowing by light attenuation (BRVO:92%,DME:6%,uvCME:3%), hyperreflective SRD deposits (BRVO:95%,DME:6%,uvCME:31%) and neuronal layer cysts for BRVO and intact hyperreflective bands(uvCME:97%,others:25%) for uvCME.
Conclusions: :
Differences in layer thicknesses and characteristic, specific morphologic alterations characterize CMEs of different origin and make them distinguishable based on SD-OCT analysis.