By means of intravenously administered fluorescein, dynamic vascular changes can be demonstrated in the choroid and retina immediately after freezing. The fluorescein leakage, which has a characteristic pattern, ceases after 72 hours due to the cessation of active choriocapillary circulation. The color photographs illustrate the development of edema, evolution of pigmentation, and changes in the choroidal circulation after cryopexy. The rapid sequence color photographs taken before, during, and after freezing show the circulation to be stopped by probe pressure prior to freezing. They also demonstrate the return of circulation in the choroidal vessels of all sizes after thawing. Histology confirms the retinal edema, necrosis, and pigmentary changes as well as the vascular changes in the choroid and resultant subretinal exudation.
Amoils SP, Haining WM. Evolution of the Cryogenic Chorioretinal Lesion. Arch Ophthalmol. 1969;81(1):11-21. doi:10.1001/archopht.1969.00990010013003