Photorefractive Keratectomy by Extimer Laser for the Correction of Myopia

Photorefractive keratectomy was performed, using the excimer laser, on 117 myopic eyes. The eyes were classified in three groups by preoperative refractive errors, Group I included eyes with myopla ranging from -2.00D to -5.75D; Group 2 included eyes with myopia ranging from -6.00D to -9.75D; Group 3 included eyes with myopia over -10.0D. The eyes were followed up over six months to one year. During the follow up period, slit lamp examination, visual acuity, refractive error, pachometer, corneal opaty, IOP and corneal topography were examined, The results were as follows; 1. Preoperative mean visual acuities were 0.07 and postoperative mean visual acuities were 0.72. 2. Postoperative refractive errors were smaller and visual acuities were better in eyes of Group I than Group 2 or 3. 3 Immediate postoperative refractive states were hyperopia and regress over 4 to 12 weeks. 4.Keratometer reading and central corneal thicknesses were decreased postoperatively, but 4 to 12 weeks later, they started to increase. 5 There were mirlimal comeal corneal peaking at 4 weeks and diminishing over the next 3 to 6 months, which were not felt to be visually signicant.

Classification of Corneal Topography and Analysis of Astigmatism based on Computer-Assisted Videokeratography

We evaluated the corneal topography of 109 eyes which have 1 diopter or more astimatism, with computer-assisted videokeratography(Eye Sys CAS). There was 11% with round pattern, 17.4% with oval pattern, 49.5% with symmetric bow-tie pattern, 19.3% with assymmetric bow-tie pattern, 2.8% with irregular pattern. 70% of subjects had right and left eyes classified into the same group. There was statistically significant difference among the patterns for keratometric astigmatism and difference among the groups which were classified by the location of the area of highest refractive power for keratometric and total astigmatism. The mean angular separation between flat and steep meridian was 89.2 degrees and ranged from 78.61 degrees to 100.67 degrees. The mean residual astigmatism was 0.547 diopter. In the with-the rule astigmatism type, when the total astigmatism less than 1.89 diopter, residual astigmatism neutralize the corneal astigmatism, but when the total astigmatism increase more than 1.89 diopter, residual astigmatism tend to increase the total astigmatism.

The Effect of Saponin on the Na+ - K+ Activated ATPase of Cattle Lens Epithelial Cell

The effect of saponin on the Na+ - K+ ATPase of anterior capsule and epithelium of cattle lens has been investigated. The experiment also designed to determine the cation of saponin on the Na+ - K+ ATPase activity in anterior capsule and epithelium of cattle lens. The following results are observed. 1. The Na+ - K+ ATPase activity of cattle lens epithelial cell membrane is inhibited by low concentration of saponin, but increased by high concentration. The strongest activity showed at the dose of 50mg% saponin concentration. 2. The activating effect of saponin on the cattle epithelial cell membrane Na+ - K+ ATPase activity is inhibited by ouabain, but the stimulation of the Mg++ ATPase by high concentration of saponin is not inhibited by ouabain. 3. The activity ratio of Na+ - K+ ATPase by high concentration of saponin is increased by raising the sodium concentration but decreased by raising the potassium concentration. 4. The Na+ - K+ ATPase activity is increased by small amount of calcium but completely inhibited by over 5mM concentration of calcium.