glycogen and Corneal-Diseases

Although diabetic retinopathy has been thoroughly studied, little attention has been given to the corneal changes of diabetic patients. Pathophysiologic and clinical findings may be related to the ultrastructural changes found in these corneas.. To investigate the ultrastructural corneal changes of diabetic patients.. Transmission electron microscopic ultrathin sections were prepared from corneas of 16 noninsulin-dependent diabetic patients (mean age, 65 years; range, 40-82 years) who suffered from the disease for a mean period of 22 years (range, 10-30 years). We used 16 corneas from healthy age-matched donors as normal controls.. In addition to the epithelial changes that include accumulation of glycogen granules, occasional focal epithelial cell degeneration, and irregular thickening and multilamination of the epithelial basement membrane, unusual 120-nm wide-spaced collagen fibril bundles were observed scattered among both Descemet's membrane and stromal matrix.. The aggregates of wide-spaced collagen fibrils, which have not been described in other basement membranes of diabetic patients, may reflect an excessive glycosylation rate.

Topics: Adult; Aged; Aged, 80 and over; Apoptosis; Basement Membrane; Cadaver; Collagen; Cornea; Corneal Diseases; Diabetes Mellitus, Type 2; Glycogen; Humans; Microscopy, Electron; Middle Aged

The corneal response to a complete tarsorrhaphy was studied in 46 rabbits for time periods up to 21 days. During the first 7 days of complete eyelid closure corneal thickness increased up to 18.4%, glycogen decreased 32.2%, and lactate rose 27.2%. A steep increase in corneal thickness to 89.8% appeared after 14 days, followed by decreasing values at 21 days, which was concomitant with the formation of extensive vascularized pannus. These results confirm previous findings that the partial pressure of O2 under closed eye conditions is substantially below physiologic requirements, affects endothelial pump capability, and results in major corneal swelling. When silicone contact lenses were fitted immediately before eyelid closure, corneal swelling 2 days after lid closure did not differ from that in eyes without lenses.

Topics: Animals; Contact Lenses; Cornea; Corneal Diseases; Edema; Eyelids; Glycogen; Lactates; Oxygen Consumption; Rabbits; Silicones; Time Factors

Topics: Adult; Aged; Animals; Basement Membrane; Blood Glucose; Cornea; Corneal Diseases; Diabetes Complications; Diabetes Mellitus; Diabetes Mellitus, Experimental; Edema; Epithelium; Female; Fructose; Glucose; Glycogen; Humans; Male; Middle Aged; Postoperative Complications; Rabbits; Rats; Sorbitol; Vitrectomy

Electron microscopy of streptozotocin diabetic rat eyes showed increased intracellular levels of tonofilaments and glycogen, thickenings and infoldings of subepithelial basement membrane and basal cell degeneration after 8 months. Glycogen, glucose, sorbitol, and fructose were measured in corneal epithelium from short- and long-term diabetic rats. The small increase in sorbitol pathway products which were found after 8 months of diabetes (less than 1.0 mosm/1 tissue water) confirmed similar findings in rabbits and humans. Thus, the morphologic changes occur in the absence of significant accumulation of sorbitol pathway products. Osmotic damage secondary to corneal epithelial cell accumulation of sorbitol is probably not a significant factor in corneal epithelial diabetic disease.

Topics: Animals; Cornea; Corneal Diseases; Diabetes Mellitus, Experimental; Epithelium; Female; Fructose; Glucose; Glycogen; Humans; Microscopy, Electron; Rabbits; Rats; Sorbitol

Topics: Acetylcholine; Amino Acids; Animals; Cattle; Conjunctiva; Cornea; Corneal Diseases; Diabetes Mellitus; Epithelium; Glucose; Glycogen; Humans; Rabbits; Tears; Vitamin A Deficiency

The increased use of donor epithelium in keratoplasty for severe corneal disease has prompted an investigation of epithelial viability during midterm storage. Glycogen, ATP, and ADP have been used as indicators of the metabolic state of epithelial cells. These substances have been measured after conventional moist-chamber storage at 4 degrees C. for 1, 2, and 12 days and after immersion at 4 degrees C. in McCarey-Kaufman medium for 1, 2, and 12 days. In addition, recovery of glycogen and ATP stores has been evaluated after warming of the tissue in the storage solution to 37 degrees C. The evidence indicates that the corneal epithelium may recover these biologically important substances, despite depletion secondary to delayed cooling of donor eyes.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Cornea; Corneal Diseases; Epithelial Cells; Epithelium; Glycogen; Humans; Tissue Donors; Tissue Preservation; Transplantation, Homologous