Eyes were enucleated, cultivated for a defined period (up to eight days) or embedded directly in TissueTek without fixation and snap-frozen in liquid nitrogen. Tissues were stored at −80°C until LCM. Eight-micrometer–thick sections were cut at −20°C and mounted on PEN-Membrane slides (no. 11505158; Leica, Wetzlar, Germany). Before LCM, morphology was exposed. Therefore sections were stained with hematoxylin for 40 seconds, washed with water (2 × 2 seconds), and dehydrated with ethanol: 2 × 70% ethanol, 2 × 96% ethanol, 3 × 100% ethanol, each for two seconds. Slides were removed from ethanol and air-dried. The system LSM 6000 (Leica) was used for LCM. For collecting the outer nuclear layer and inner retina separately, small tubes (no. 04.100.0100; Nerbe Plus, Winsen, Germany) filled with 30 µL RLT Buffer (from QIAGEN RNeasy Micro Kit; Qiagen, Hilden, Germany) containing 0.001% β-mercaptoethanol were used. Approximately 40 sections were collected per retina and retinal layer. Immediately after LCM, the samples were vortexed for 15 seconds, snap-frozen in liquid nitrogen, and stored at −80°C until RNA isolation. RNA isolation was performed as described below. The quality and quantity of the RNA were assessed with NanoDrop 2000 (Peqlab, Erlangen, Germany).