[Ultrastructural changes of the trabecular meshwork in glucocorticoid induced glaucoma].

PURPOSE

Steroid-induced glaucoma in rabbit ocular was established to observe the ultrastructural changes in trabecular meshwork,and to preliminarily study the mechanisms of increased resistance of aqueous outflow in steroid-induced glaucoma.

METHODS

Forty New Zealand white rabbits were randomly divided into four groups, namely,control group (n = 10 rats),drops drug group(n = 10 rats), Injecting drug group(n = 10 rats) and drug combination group (n=10 rats). For three consecutive days before the experiment,using the Schitoz's tonometer to measure intraocular pressure(IOP) at 8am, 10am, and 12am each day,obtained the average,and finally calculated basis IOP of these rabbits. The rabbits eyes in drug combination group of were treated with dexamethasone sodium phosphate solution (0.5%)for 8 weeks,three times a day, and given injection of triamcinolone endure (3 mg) weekly. While the rabbits eyes in the control group were treated with sterile saline in the same period of experiment.After 4 days,IOP of the rabbit was measured by Schitoz's tonometer weekly( the IOP was measured at 8am, 10am, 12am each day for the average value).The rabbit whose IOP was more than 21.97 mmHg and continued for one week is regarded a successful animal model as Corticosteroid. After 8 weeks,the eyes of control group and Corticosteroid rabbits was made for Transmission electron microscopy(TEM) specimen which was used to study the ultrastructural of trabecular meshwork cell.

RESULTS

1.The Rabbit-based IOP was (18.082±2.398) mmHg（n=80）,in the drug combination group The IOP of rabbit is up to (24.056±1.245) mmHg after three weeks，which was significantly higher compared with that of(18.254 ± 3.465) mmHg in the control group,the difference had significance(p<0.05),after six weeks, which reached the peak, up to (30.214±0.766) mmHg,in the eighth week, up to (29.144±0.685) mmHg, the IOP of 16 rabbit eyes from 20 rabbit eyes in the exprimental group increased.The positive rate was 80%.2. After treatment with dexamethasone,the abnormality of nucleus of the trabecular meshwork cell was increased, microfilament and microtubules among interstitial cells also increased ,cytoplasmic vacuolation, rough endoplasmic reticulum expansion, as well as an increase in intercellular amorphous material.

CONCLUSION

1.The glucocorticoid-induced high intraocular pressure rabbit model has been successfully established in drug combination group.2.A series of changes in the cytoskeleton observed under the transmission electron microscopy are an important part of glucocorticoid-induced elevation of intraocular pressure.