Anatomical effects of ablation of the anterior retina in small animal eyes

To provide anatomical data after cryo and laser ablation of the anterior retina in mice, rats, and rabbits as a prerequisite to make surgical procedures in these species safer. 12 eyes per species of C57BL/6J wild-type (wt) mice, Brown Norway rats, and Chinchilla Bastard rabbits, respectively, were treated with laser or cryo coagulation in the anterior retina. Diode laser and cryo coagulation were applied transsclerally. The coagulation effect was evaluated histologically after three weeks and a three-dimensional (3D) reconstruction was performed from serial microscopic sections to improve visualization of the effects. Lesion diameter differed significantly between cryo and laser coagulation across all species (911.61 ± 52.59 μm vs. 775.89 ± 56.11 μm, p < 0.05 for mice, 686.44 ± 42.98 μm vs. 519.19 ± 30.59 μm, p < 0.0001 for rats, 415.32 ± 28.43 μm vs. 313.65 ± 29.35 μm, p < 0.05 for rabbits). The ratio of retinal thickness before and after cryo and laser coagulation was 0.41 ± 0.01 and 0.50 ± 0.03 for mice, 0.46 ± 0.03 and 0.51 ± 0.01 for rats, and 0.45 ± 0.01 and 0.51 ± 0.01 for rabbits, respectively. No significant side effects were observed. Using segmentation and registration algorithms, the microscopic images of each stack were aligned and 3D visualized. Cryo pretreatment of the anterior retina provided a broader-based scarring compared to laser pretreatment and can possibly help to optimize experimental vitreoretinal procedures to test the biocompatibility and function of prototype devices for retinal stimulation.