Histological Changes of the Vitreous and Retina in Retinal Lattice Degeneration

PURPOSE: To investigate of the histological characteristics of the lattice degeneration of the human peripheral retina. METHODS: The histological characteristics of the lattice degeneration of the retina was checked by flat preparation and serial section of the lattice lesion in three eyes was investigated by transmission electron microscopy. RESULTS: Flat preparation showed lattice lesion with a hole at the lateral margin with overlying sclerotic vessel and pigment clumping within the lesion. The ultrastructural initial findings showed that the collagen filament in the vitreous cavity was continuous with Muller fiber of the retina with the defect of the inner retina. The full-thikness defect of the sensory retina leaded to the retinal hole. The vascular wall was replaced and occluded by fine fibrillar collagen. The glial cell proliferated into the neural tissue of the sensory retina. These glial cells may secrete long spacing collagen (LSC) and curvilinear material shown at the area of the sensory retinal defect and near the vitreoretinal interface. CONCLUSIONS: These results suggest that the thinning of the retina occurs from the inner retina leading to retinal hole as the lattice degeneration progresses. LSC and curvilinear material are suggestive of derivatives derived from the extracellular material secreted from the glial cell.

The Cellular Characteristics of the Secondary Pupillary Membrane

PURPOSE: This study was performed to investigate the cellular characteristics of the secondary pupillary membrane. METHODS: The secondary pupillary membrane was removed from the anterior lens surface during cataract extraction from 2 patients with cataract associated with uveitis. Specimen from one patient was stained with hematoxylin-eosin with flat preparation method. Specimen from the other patient cultured for 1 and 2 weeks was observed with transmission electron microscopy. RESULTS: The flat preparation showed the neovascular membrane with pigment-laden cells. The cultured cells consisted of the well preserved vascular components which had the vascular endothelial cells and pericyte and pigment-laden cells lined by basement membrane on first week of culture. The iris pigment epithelial cell which contained the pigment granules within cytoplasm and lined by basement membrane were observed on second week of culture. CONCLUSIONS: These results suggest that the secondary pupillary membrane consists of vascular membrane and pigment epithelial cell of iris which is a major component of secondary pupillary membrane and secrets extracellular matrix.