Immunohistochemical Changes of Rabbit Cornea After Excimer Laser Surface Ablation: collagen type III, IV, VI, VII

We performed photorefractive keratectomy(PRK) on 10 rabbit eyes and determined the distribution of collagen type III, IV VI, VII at postoperative 2, 4 and 6 months to examine immunohistochemical changes after PRK. Type III collagen was not found in the normal cornea but strongly detected in the regenerated corneal stroma at all intervals. It was most prominent at 2 months after surgery and then decreased. Type IV collagen was detected in basement membrane in both normal and ablated corneas at all intervals and the staining was more intense in ablatd corneas than in normal cornea. There was no difference of staining intensity among the groups of different intervals. Type IV collagen was found in both normal and healed corneal stroma at all intervals and there was no difference of staining intensity between normal and ablated corneas and among the groups of different intervals. Type VII collagen was observed as a linear continuous band along the basal surface of epithelium in normal cornea. At 2 months after surgery, type VII collagen staining in basement membrane zone became denser than normal cornea, but segmented. At 4 months after surgery, continuous band of collagen type VII staining was observed, but it was less intense than in normal cornea. At 6 months after surgery, the intensity of continuous band of collagen type VII was the same as in normal cornea. This results suggest that the presence of type III collagen in the regenerated cornea may be related to the development of postoperative subepithelial opacity after PRK and the normalization of collagen type IV and VII at postoperative 6 months may mean the complete reestablished of the adhesion of regenerated epithelium and stroma.

The Absorption of Intraocular Gas and Its Relationship with IOP

We performed the intravitreal injection of air and pure perfluoropropane(C3F8) gas in the pigmented rabbits and observed the changes of gas levels by the ultrasonography. We also observed the changes of the intra-ocular gas levels by the ultrasonography and measured the intraocular pressures(IOPs) in 9 patients who had undergone vitrectomy and fluid-gas exchange with 20% sulfur hexafluoride(SF6) and 14% perfluoropropane(C3F8) gases. In the pigmented rabbits, the air was not expanded and completely absorbed within 2 days, and the C3F8 gas was expanded maximally at 3 to 7 days and completely absorbed after 3 weeks. Among nine human eyes treated with vitrectomy and fluid-gas exchange, the intraocular pressures were elevated above 25mmHg at 1 day after operation in 2 eyes, which were controlled with medical therapy. The lOPs were significantly correlated with the amount of the intraocular gases(r=0.3476, p<0.05). The assessment of intraocular gas level by ultrasonography seems to be easier and more objective method than others previously reported.

The Effect of Temperature of Infusion Fluid on Retina During Vitrectomy

To find out the optimal temperature of infusion fluid during vitrectomy, five rabbit eyes were infused with body temperature (37C) Balanced Salt Solution Plus (BSS Plus, Alcon Laboratories) and the other five eyes with room temperature (22C) BSS Plus. We recorded the ERGs before operation and 2 days, 7 days and 28 days after operation and each recording was plotted on paper with automatically measured amplitude. The a-wave amplitude, b-wave amplitude and b/a ratio showed no significant difference between 22C and 37C groups before operation and 2 days, 7 days and 28 days after operation. The a-wave amplitudes were decreased, b/a ratios were increased and b-wave amplitudes was not changed after operation in both 22C and 37C group. We suggest that there is no difference in the effects of infusion fluid to retinal function whether we use room temperature or body temperature infusion fluid.

The Corneal Endothelial Cell Density in Korean by the Different Types of Specular Microscopy

The normal corneal endothelial cell count was measured by the non-contact(Nikon, AS-1, Japan) and contact type(Bio-optic, LSM 2000, USA) specular microscopy. The results of two types were compared to investigate the possible differences in types of specular microscopy. No statistically significant differences were found between the results from the non-contact type and those from the contact type; the mean number of normal Korean corneal endothelial cells according to the age was 2795 in the 2nd decade, 2615 in the 3rd decade, 2463 in the 4th decade, 2283 in the 5th decade, 2119 in the 6th decade, 2019 in the 7th decade and 1920 over the 8th decade.

Analysis of lid Contours in Children

We measured the height and length of palpebral fissure, intercanthal distance and upward deviation of lateral canthus, and ovserved presence of double lid and epicanthal fold of 316 children who had no ocular disease except refractive anomaly by the use of standardized photographic method. We also analyzed the results according to the age, sex and the degree of refractive anomaly. The mean of central height of palpebral fissure was 8.0mm and the mean of maximal height was 8.1mm. In most of cases, the point where the height became maximal was at the center of the palpebral fissure and there was no difference accorging to laterality, sex, age and the degree of refractive anomaly. The length of palpebral fissure was 20.0mm in average and there was no difference according to laterality, sex and the degree of refractive anomaly, but it increased with the increasing age. The intercanthal distance was 33.8mm in average and increased with the increasing age but was not influenced by sex and refractive anomaly. The lateral canthus was deviated upward in relation to medial canthus by 5.90 in average and it was more deviated in female than in male. There was no difference according to laterality, age and refractive anomly, The double lid was present in 28.2% of total subject and it was equally frequent in male and female, and more frequent in the older age group. The epicanthal fold was present in 54.7% of total subject and there was no difference accrding to age and sex. Most of them were epicanthus tarsalis(56.1 %) and epicanthus palpebral is type.