Due to tissue transparency, histologic analysis was performed on the corneas to quantify ablation crater and thermal damage depths. Immediately after the procedure, the eyes were placed in formalin. With the pupil center being the pole, the eyes were sectioned latitudinal and the extra material was discarded leaving only the polar cornea region. The corneas were trimmed to thick longitudinal for histological processing and various samples were stained with Masson’s Trichrome. The craters were viewed and measured using a microscope equipped with a CCD camera. A representative image for each sphere configuration is shown in Fig. 6. An additional native cornea histology image is shown to visualize the PFM and paraxial foci of the 300-μm diameter sphere configurations. Ablation craters depths of 12, 25, and 10 μm and thermal damage depths of 70, 40, and 30 μm were measured for one, three, and five spheres, respectively. Although tissue staining was inconsistent between batches, the darker colored region in each image represents thermal damage. The tearing and folding observed in the histology images, particularly in the stroma region (blue stained) for the one and five sphere configurations was an artifact of the histological processing, extending laterally far beyond the treatment area into the native tissue, and was therefore not indicative of tissue damage caused by the laser. However, some slight alteration in the stroma can be seen for the one and three sphere configurations (yellow stained), corresponding to deeper thermal damage in those cases.