Expression of Hypoxia-Inducible Factor-1alpha(HIF-1alpha) in the Experimental Model of Choroidal Neovascularization

PURPOSE: The expression of hypoxia-inducible factor-1alpha(HIF-1alpha) in the choroidal neovascular membrane (CNV) was investigated. METHODS: CNV was induced in the eyes of Brown Norway rats by 545 nm argon laser photocoagulation into the eye, and fluorescein angiography (FAG) was performed to identify the early hyperfluorescence and the late leakage after 2 weeks of the photocoagulation. Three days after FAG, the eyeball was harvested and the expression of vascular endothelial growth factor (VEGF) and HIF-1alpha was identified by immunohistochemical methods. RESULTS: Twenty-nine of 37 photocoagulation sites of the eyes showed CNV formation on FAG. Immunohistochemical staining of the laser photocoagulation-induced CNV tissues revealed the expression of VEGF and HIF-1alpha in the sites. CONCLUSIONS: These results suggest the possibility of the involvement of HIF-1alpha in the VEGF expression and the pathogenesis of CNV in the laser photocoagulation-induced CNV rat model.

Apnea Associated with General Anesthesia in the Surgical Treatment of Retinopathy of Prematurity and its Risk Factors

We evaluated the relationship between preoperative risk factors[gestational age, birth weight, postconceptual age and weight at operation, duration of operation, duration of anesthesia, abnormalities in neurosonogram, bronchopulmonary dysplasia]and apnea with or without bradycardia, for which mechanical ventilation was necessary after general anesthesia in the surgical treatment of retinopathy of prematurity[ROP]. Thirty-eight patients [21%]developed apnea and thirteen patients[7%]had bradycardia out of 183 patients. Retrospective study was performed and risk factors were analyzed by logistic regression. Gestational age, birth weight, postconceptual age and weight at operation and bronchopulmonary dysplasia showed the positive correlation with postanesthetic apnea and bradycardia. Duration of operation showed the positive correlation with postanesthetic apnea but not with postanesthetic bradycardia. In logistic regression without confoundings, weight at operation and bronchopulmonary dysplasia were correlated with postanesthetic apnea. Receiver operating characteristic curve analysis revealed that patients with weight under 2, 600gm at operation suffered from apnea more frequently than those with weight over 2, 600gm. In conclusion, patients with weight under 2600gm or bronchopulmonary dysplasia are at greater risk for postanesthetic apnea and optimal pre-and postanesthetic management should be prepared for these patients.

The Relationship between the Mean Height of Contour of the Retinal Surface at the Temporal Disc Margin and the Reference Height in Analyzing Optic Disc using Heidelberg Retina Tomograph

The relationship between the amount of posterior displacement of the retinal surface at the temporal disc margin and the reference height(HRef)in analyzing optic disc using Heidelberg Retina Tomograph(HRT;Heidelberg Engineering, Heidelberg, Germany)was evaluated. The displacement was measured as mean height of contour(MHC)in the temporal 40degrees C segment(20degrees C superior and 20degrees C inferior to the horizontal midline)of optic disc. HRef is a value representing the location of the standard reference plane. The accordances of HRef and stereometric parameters between right and left disc were also evaluated. MHC in the temporal 40 degrees C and nasal 40 degrees C segment, HRef, and stereometric parameters of optic disc were measured with the HRT in 244 eyes of 122 subjects. HRef was 0.376+/-0.099 mm in the right disc and 0.385+/-0.090 mm in the left disc. There was good correlation between HRef and MHC in the temporal 40degrees C segment(r=0.97, p<0.01), but poor in the nasal 40 degrees C segment(r=0.29, p<0.01). The accordances of HRef and stereometric parameters increased as the difference of MHC in the temporal 40degrees C segment between right and left disc decreased. HRef was affected by the amount of posterior displacement of the retinal surface at the temporal disc margin, which occurs in instances such as a tilted disc. We should find the method to adjust stereometric parameters to the amount of disc tilt.

Compartive Accuracy of the SRK II, SRK/T and Holladay Formulas for Intraocular Lens Power Calculation in Severe Myopic Eyes

The predictive accuracy of the SRK II, SRK/T and Holladay formulas was evaluated in 22 eyes with sever myopia who had phacoemulsification and implantaton of posterior chamber IOL without suture. These patients were followed up for at least 6 months postoperatively. Correlation coefficient between the predicted refraction and actual refraction was 0.57(P0.05). The percentage of the eye with hyperopic shift(more hyperopic actual refraction than the predicted refraction) was 77% in the SRK II, 77% in the SRK/T and 86% in the Holladay, but there was no statistically significant difference between each formula(p>0.05). In conclusion, the SRK/T has the better predictive accuracy than the SRK II and Holladay in severe myopia and hyperopic shift tends to occur with the application of all three formulas.