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

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

Diurnal changes of lysosomes including ultrastructural changes of phagosomes and acid phosphatase reactions in phagosomes, as well as diurnal biochemical changes in cathepsin D activity, were studied in the retinal pigment epithelium (RPE) of the rabbit. The rabbit was maintained on a natural light-dark cycle over seven days in fall and was sacrificed at various times during the day and night. The number of lysosomes or phagosomes in the RPE was the highest at 1.5 hours after exposure to sunlight (8:00 AM), and thereafter decreased with time. Three types of phagosomes were observed and acid phosphatase reactions were different in each type of phagosome; the fresh phagosomes were negative or positive, lamellar bodies positive, and dense bodies partially positive. The biochemical activity of cathepsin D was the highest at 8:00 AM, and this was consistent with the time of peak in phagocytic activity in the RPE. This report shows that phagocytic activity in the RPE occurred in the early stage after exposure to sunlight, and that fresh phagosomes were sequentially degraded to lamellar or dense bodies. Cathepsin D activity also increased, and this was consistent with the phagocytic activity in the RPE.
Acid Phosphatase/metabolism ; Animals ; Cathepsin D/metabolism ; Cell Count ; Choroid/metabolism/ultrastructure ; Circadian Rhythm/*physiology ; Lysosomes/*metabolism/ultrastructure ; Phagosomes/*metabolism/ultrastructure ; Pigment Epithelium of Eye/*metabolism/ultrastructure ; Rabbits