Retinal vessel occlusions might lead to ischemia of the inner retina, more severe so in artery occlusions. Intracellular edema may develop and decrease transparency of those layers, showing retinal edema. In spectral domain optical coherence tomography (SD-OCT) retinal reflectivity changes as a result of retinal edema. The investigators examine the reflectivity changes of different retinal layers between healthy eyes and eyes with retinal artery occlusion and ischemic or non-ischemic vein occlusions. Aim of the study is to evaluate whether those changes can be used to measure the level of ischemia in the inner retina.

Several studies tried to classify retinal ischemia due to retinal artery or vein occlusion into different grades. In some cases prognosis is dependent on grade of severity, especially in cases of retinal vein occlusion. State of the art to Diagnose the severity of retinal ischemia is lfuorescein angiography. However, this technique is invasive and might cause Problems like anaphylactic shock. Optical coherence tomography is a non-invasive technique, but up to now there is no standardized method to quantify the grade of severity of retinal ischemia in such conditions like retinal vessel occlusion. The study hope to find criteria by which such a classification can be constructed.

Inclusion Criteria:

• acute Retinal vessel occlusion on one eye
• healthy contralateral eye
• examined with spectral Domain optical coherence tomography

Exclusion Criteria:

• retinal occlusion older than 1 week
• OCT Image not obtainable/missing

Chart Review of patients treated b/o retinal vessel occlusion, who were examined with optical coherence tomography