Advantages:

To develop the coefficient of ischemia in order to characterize pathological changes of retinal architectonics in microvascular occlusion in ischemic diabetic maculopathy according to non invasive method spectral optical coherence tomography in comparison to non ischemic retina without usage of fluorescent angiography.

Methods:

There were 25 eyes (18 patients) with diabetic macular ischemia to which along with general clinical ophthalmological investigation, fluorescent angiography (FA) and spectral domain optical coherence tomography (SD OCT) (Topcon 3D OCT Mark2) were carried out the same day. The study group consisted of ischemic areas in macula of 12 men and 6 women (age 56 ±15) with diabetes mellitus. Non-ischemic regions of retina of the same eye in corresponding regions to ischemic areas (mirrored on horizontal axis along the center of macula) were included in a control group. FA images were imported in Topcon 3D OCT software for PinPoint registration to allow precise determination of ischemic and corresponding non ischemic areas on OCT. Retinal layers on SD OCT were divided by us into three structural formations for performing morphometry measurements: internal layers (ILM, NFL, GCL, IPL,), medium layers (INL, OPL), outer layers (ONL, OLM, IS/OS, PE). We propose the following calculation of “Ischemic coefficient” (index of ischemia), which indicates the minimal value of thinning of ischemic retina in comparison to corresponding unchanged (control) region and was calculated according odds ratio and formula (Coefficient of ischemia=thickness of ischemic retina (mkm)/thickness of unchanged retina).

Effectiveness / Safety:

Non-invasive SD-OCT allows diagnosing the capillary occlusion without performing of invasive FA.

Take home message:

The obligatory conditions for occlusive maculopathy were the following: index of ischemia less than 0.96 under conditions of homogenization and thinning of internal layers, thinning of middle layers and unchanged thickness of its outer layers. The results of retinal morphometry showed the band of thickening of transitional zone between ischemic and perfused regions, which can indicate that in pathological process of retinal occlusion the stage of edema can precede the stage of atrophy.