Excimer laser photorefractive keratectomy for astigmatism

The effectiveness of excimer laser photorefractive keratectomy (PRK) for astigmatism was evaluated. We treated 136 eyes of naturally occurring myopic astigmatism using the 193-nm excimer laser with an expanding slit and an iris diaphragm, and followed for a minimum of 6 months. At 6 months after operation, the mean refractive cylinder decreased from 1.62 +/- 0.88 D preoperatively to 0.48 +/- 0.48 D. For detailed analysis of the results, the surgically induced refractive change (SIRC) was determined from the preoperative and postoperative refractions by vector analysis of astigmatism. When we compared the cylinder of the SIRC with the preoperative refractive cylinder, the effect of the cylindrical ablation was 93.9 +/- 36.7% at 6 months. The axial error of the cylinder of the SIRC to the preoperative cylindrical axis was 5.9 +/- 10.2 degrees at 6 months. These results suggest that excimer laser PRK with an expanding slit appears to have a significant effect for the correction of astigmatism.

The reproducibility of the Schirmer test

The Schirmer test was performed 1350 times in 110 normal individuals and 15 dry eye patients to investigate the significance of the test as a diagnostic method for dry eye. The reproducibility of the Schirmer test was 54.5% in normal individuals and 41.9% in dry eye patients. There was no difference in the reproducibility between the groups with topical anesthesia and those without it. The ratio of misdiagnosis by Schirmer test was 48.4%. These results suggest that it is impossible to differentiate dry eye patients from normal individuals by the Schirmer test.

The Effect of Steroid on the Viability of the Endothelial Cell of Stored Cornea

Autolysis, which is brought about by the release of lysosomal hydrolytic enzymes, has been prevented in cornea with the use of lysosomal membrane stabilizers, such as corticosteroid. So, we performed this study to see whether corticosteroid could reduce endothelial damage in stored corneas, or not. The experiment was performed on 15 albino rabbits which were killed by intravenous air injection. 40 microgram of hydrocortisone sodium succinate was injected into the anterior chamber of the enucleated eye. The whole eye ball was stored in the moist chamber at 4 degrees C for 24 hours, 48 hours, or 72 hours, then the cornea was removed and stained with trypan blue. Unstained endothelial cells were counted with light microscope to determine the density of viable endothelial cells. Same procedures were done on the contralateral eye with injecting normal saline into the anterior chamber instead of hydrocortisone as a control. The density of viable endothelial cells in the steroid group was higher than that in the control group by 1.75%, 14.39%, and 27.40% in 24 hours, 48 hours, and 72 hours storage, respectively.

The Effect of Steroid on the Viability of the Endothelial Cell of Stored Cornea

Autolysis, which is brought about by the release of lysosomal hydrolytic enzymes, has been prevented in cornea with the use of lysosomal membrane stabilizers, such as corticosteroid. So, we performed this study to see whether corticosteroid could reduce endothelial damage in stored corneas, or not. The experiment was performed on 15 albino rabbits which were killed by intravenous air injection. 40 microgram of hydrocortisone sodium succinate was injected into the anterior chamber of the enucleated eye. The whole eye ball was stored in the moist chamber at 4 degrees C for 24 hours, 48 hours, or 72 hours, then the cornea was removed and stained with trypan blue. Unstained endothelial cells were counted with light microscope to determine the density of viable endothelial cells. Same procedures were done on the contralateral eye with injecting normal saline into the anterior chamber instead of hydrocortisone as a control. The density of viable endothelial cells in the steroid group was higher than that in the control group by 1.75%, 14.39%, and 27.40% in 24 hours, 48 hours, and 72 hours storage, respectively.