This study was performed to investigate the sequential changes of the retinal tissue in tissue culture condition. The human sensory retinal tissues were cultured for up to 2 weeks and 4 weeks, respectively. The initial changes showed the separation of the intercellular space and the consequent widening of the intercellular space with prolapse of cytoplasmic processes into the widened intercellular space. The internal limiting membrane was also separated from the inner retina, which led to the prolapse of the cytoplasm of the Muller cell. The growth of the Muller cell was most prominent during the 4-weeks' tissue culture period. These findings suggest that the Muller cell might contribute to the formation of cellular membrane in case of the defect of the internal limiting membrane in several pathologic conditions.
Adult ; Cell Membrane/ultrastructure ; Cells, Cultured ; Humans ; Male ; Middle Aged ; Neuroglia/*ultrastructure ; Retina/*ultrastructure

Intragcular pressure (lOP) was artificially elevated and maintained in rabbits for up to 12 hours at levels 40, 60, 80, and 100 mmHg. Electroretinographic (ERG) responses showed gradual decline and later disappeared depending on the pressure. ERG responses were initially normal to supernormal at all lOP levels except 100 mmHg, and then showed gradual decline to extinction except in one eye of the 40 mmHg group. Ultrastrurtural damage was also pressure and time dependent. After 12 hours of the increased lOP, no damage to the ultrasfrurture of the retina was detected at 40mmHg, although the ERG was severely affected. Electron microscopic studies showed flattening of the pigment epithelium and swelling of mitochondria which appeared first at 60 mmHg; severe damage of mitochondria and the basal infoldings of the pigment epithelium at 80mmHg; and severe damage of all the retinal tissues at 100 mmHg. The critical duration of the elevated lOP which decreased the amplitude of the ERG was found to be 5 hours for 40 mmHg, 1 hour for 60 mmHg, and 30 minutes for 80 mmHg. The critical lOP which affected the ultrastrurture after 12 hours, lied between 40 and 60 mmHg.
Animals ; *Electroretinography ; Intraocular Pressure ; Ocular Hypertension/*physiopathology ; Pigment Epithelium of Eye/ultrastructure ; Rabbits ; Retina/physiopathology/*ultrastructure ; Time Factors

We studied the ultrastructural features of four consecutive subfoveal neovascularmembranes (SFNM) associated with age-related macular degeneration. Cellular components of the membranes included retinal pigment epithelial (RPE) cells, endothelium-lined vascular channels, macrophages, myofibroblasts, fibrocytes, glial cells, erythrocytes, and lymphocytes. Extracellular interstitial constituents included collagen fibrils, basal laminar deposits, fibrin and young elastic fibrils. These findings show that SFNMs consist of various cells originating from surrounding tissues and vessels. Among these RPE cells and macrophages are the main cellular components and in conjunction with various extracellular matrix, especially collagen, may play an important role in the formation and maintenance of the membranes.
Basement Membrane/surgery/ultrastructure ; Humans ; Macular Degeneration/complications ; Microscopy, Electron ; Retina/*ultrastructure ; Retinal Neovascularization/etiology/*pathology/surgery

Experimental total retinectomy was performed in pigmented rabbit eyes to in vestigate its long-term effects on the operated and nonoperated opposite eyes from both clinical and histological aspects. There was no significant change in intraocular pressure between the preoperative and postoperative measurements during the six months after surgery. Rubeosis iridis, intraocular hemorrhage and phthisis bulbi were not evident in the operated and opposite eyes. Light microscopic examination revealed congestion of the choroidial vessels. There were scattered areas of retinal pigment epithelial cell proliferation. Transmission electron microscopic examination showed apiral mounding of the retinal pigment epithelium. Apical processes were short and reduced in number. Apical processes of the retinal pigment epithelial cells interdigitated with surface processes of the proliferating retinal pigment epithelial cells. There were numerous melanosomes in the cytoplasm of the proliferating retinal pigment epithelial cells. Cell junctions between the retinal pigment epithelial cells were well preserved.
Animals ; Intraocular Pressure ; Longitudinal Studies ; Pigment Epithelium of Eye/ultrastructure ; Prognosis ; Rabbits ; Retina/*surgery

Transpupillary retinal photocoagulations were performed on ten eyes of five pigmented rabbits using a diode laser (Nidek Co., LTD, Aichi, Japan) emitting infrared radiation at 800 nm wavelength. A histological and an ultrastructural study on the treated eyes were done at 1, 3, 5, and 7 days after retinal photocoagulations. The purpose of this study was to observe the sequential changes in the retina and the choroid following transpupillary diode laser retinal photocoagulations at the parameters of laser power which produced a grayish white retinal discoloration with distinct white center. It seemed that the lesion was grade 3 retinal photocoagulation by Tso et al's classification. It appeared that the parameters necessary to produce grade 3 photocoagulation lesions were 160 mW power, and 0.2 second duration at 200 microns size. In general, with an agreement to other reports, histologic study of the diode laser lesions showed that the outer retina was damaged more severely than the inner retina. However, on day 1 after laser treatment, the alterations were more profound in the inner retina than in the outer retina and an occasional swelling of the axons in the nerve fiber layer was observed on the ultrastructural study. The results observed have not been found in other previous studies and suggest that the inner retina might be injured directly by 800 nm wavelength diode laser radiations. Thus we could conclude that 800 nm wavelength diode radiation might be absorbed by melanin pigment and also by other chromophores contained in inner retinal tissues. Further studies must follow to verify the laser-tissue interactions in diode laser retinal photocoagulations.
Animals ; Laser Coagulation/*adverse effects ; Rabbits ; Retina/pathology/*radiation effects/ultrastructure

OBJECTIVETo investigate the injury in the retina of rats exposed to n-hexane.

METHODSThirty-two SD male rats were randomly divided into control group and four n-hexane groups. The rats in the four n-hexane groups inhaled 35.2 g/m3 n-hexane statically for 1, 3, 7 and 14 days respectively (6 rats in every group) while 8 rats in the control group inhaled air. Histopathology and ultrastructure changes of the retina of rats were analyzed.

RESULTSRats in control group had clear layers of retinal structure, stained evenly and with regular cell shape. Retinal degeneration was observed in the rats exposed to n-hexane for 7 d and 14 d, and aggravated by degrees with time exposed to n-hexane. In the rats exposed to n-hexane for 14 d, the outer segments of photoreceptor were arranged in a confusing order, and topically there appeared dissolution; in the inner segments, mitochondria were swollen or disappeared. Pyknotic chromatin and cytoplasmic edema were observed in the outer nuclear layer. There were degeneration of horizontal cells, bipolar cells and amacrine cells in the inner nuclear layer. Cytoplasmic edema and organelle dissolution were observed in ganglionic cells. In the neurofibromas layer, outer and inner plexiform layers, there was neuron cell tuber edema, and the microfilament and vacuole of synapse decreased.

CONCLUSIONThe histopathology and ultrastructure of retina are damaged in the rats exposed to n-hexane, thus leading to ocular fundus disease.

Animals ; Hexanes ; toxicity ; Male ; Rats ; Rats, Sprague-Dawley ; Retina ; drug effects ; pathology ; ultrastructure

PURPOSE: To investigate the asymmetry of the retinal nerve fiber layer thickness (RNFLT) with respect to the horizontal and vertical meridian and between the right and left eye in normal subjects. METHODS: The RNFLT was measured in 121 normal volunteers by optical coherence tomography (OCT). The RNFLT was analyzed by dividing the circle scanning area (diameter 3.4 mm) around the optic disc into 4 quadrants and 12 sectors. RESULTS: There was a significant difference between the RNFLT of the nasal and temporal quadrant in individual eyes. There was a significant difference between the RNFLT of corresponding sectors with respect to the vertical or horizontal meridian in individual eyes. The nasal and temporal RNFLTs were asymmetrical between the right and left eye in the quadrant and sector analysis. The RNFLT of the nasal and temporal quadrant was thicker in the right eye. The nasal and inferior RNFLT measured by OCT had a significant correlation with degree of refractive error. CONCLUSIONS: In normal subjects without significant anisometropia, there was significant asymmetry of the RNFLT for each eye as well as between the right and left eye.
*Tomography, Optical Coherence ; Retinal Ganglion Cells/*ultrastructure ; Retina/*cytology ; Reference Values ; Optic Disk/cytology ; Nerve Fibers/*ultrastructure ; Male ; Humans ; Female ; Adult

PURPOSE: To determine the normal range of retinal nerve fiber layer (RNFL) thickness of normal children and adolescents by optical coherence tomography (OCT). METHODS: This study analyzed 144 eyes of 72 normal children and adolescents by OCTIII (Zeiss-Humphrey, San Leandro, CA., USA) and the results were compared with the RNFL thickness of Korean adults. RESULTS: The mean RNFL thickness of the 72 normal children and adolescents was 105.53+/-10.33 micrometer. The mean values for left and right eyes were 104.28+/-7.68 micrometer and 106.79+/-12.98 micrometer, respectively. There was no significant difference in mean RNFL thickness between the 4 quadrants of the left and right eyes (p=0.926). Additionally, the mean RNFL thickness showed a similar size pattern regardless of age (p=0.99). RNFL thickness was found to be greater in adults than in children or adolescents, although the difference was not statistically significant (p=0.295. Likewise, no significant difference was found with gender (p=0.822) or in the pattern of RNFL thickness of 12 sectors between children and adults (p=0.08). CONCLUSIONS: This study reports RNFL thickness, as determined by OCT, for normal children and adolescents. We found this measurement method to be suitable for the early diagnosis of glaucoma and to the examination of its progression in these subjects. The findings could be used as clinical parameters for adolescent glaucoma.
Tomography, Optical Coherence ; Retina/*anatomy & histology ; Reference Values ; Nerve Fibers/*ultrastructure ; Male ; Humans ; Female ; Child ; Adult ; Adolescent

Electron microscopic examination of proliferative membranes in retinopathy of prematurity (ROP) was performed in order to evaluate the components of the membranes. The proliferative membranes were obtained from nine patients with ROP stage 5 during pars plicata lensectomy, vitrectomy, and delamination of membrane. Fibrous astrocytes, myofibroblasts, lymphocytes, macrophages, and calcification were found respectively in two cases, and fibroblast-like cells were found in one case. Varying amounts of collagen tissues were found in eight cases and vascular tissues in four cases. Most of membranes were hypocellular and composed mainly of collagen matrix. It is considered that fibrous astrocytes, myofibroblasts, fibroblasts, and vascular structures are involved in the formation of proliferative membranes of ROP, and that later these cells degenerate and disappear, and that finally only collagen matrix remains in the membranes.
Cataract Extraction ; Child, Preschool ; Gestational Age ; Humans ; Infant ; Infant, Low Birth Weight ; Infant, Newborn ; Microscopy, Electron ; Retina/*ultrastructure ; Retinopathy of Prematurity/*pathology

The whole retina, except for the medullary fiber zone in a rabbit eye, is supplied by choroidal circulation. Therefore, the histopathological changes of the sensory retina due to choroidal circulatory disturbance in rabbits may be comparable to that of the human sensory retina in the case of ophthalmic artery occlusion. This study was carried out to evaluate the histopathological changes of the ischemic retina secondary to the occlusion of choroidal circulation. The experimental occlusion of all posterior ciliary arteries and anterior ciliary arteries in the horizontal rectus muscle of rabbit eyes was performed and the subsequent histopathological changes of the sensory retina were observed by transmission electron microscopy. The morphological changes of the sensory retina following the occlusion of the ciliary arterial system are as follows: severe loss of the inner and outer segments of the photoreceptor, mild to moderate degeneration of the ganglion cells, and excellent preservation of the Muller's cell fibers and the extension of the cytoplasmic villous processes to the cytoplasmic vacuolar spaces of other degenerated cells. These findings indicate that the Muller's fibers in the ischemic condition of retina might contribute to the formation of gliosis or scarring of a damaged retina.
Animals ; Arterial Occlusive Diseases/*complications ; Arteries ; Choroid/*blood supply ; Ciliary Body/*blood supply ; Ischemia/*etiology/pathology ; Rabbits ; Retina/*ultrastructure ; *Retinal Vessels