Effect of mitomycin-C on corneal endothelial cell parameters after refractive surface ablation procedures

Background: The effect of mitomycin-C (MMC) on the reduction of endothelial cell count in the cornea remains controversial. We aimed to evaluate the effect of MMC on corneal endothelial cell parameters after refractive surface ablation procedures, including photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). Methods: In this interventional, comparative, follow-up study, 342 eyes of 171 patients were followed up for 6 months. Patients undergoing PRK or LASEK were included and were divided into two groups: group one (188 eyes of 94 patients) with an ablation depth of ? 65 µm and who received intraoperative 0.02% MMC for 30 s, and group two (154 eyes of 77 patients) with an ablation depth of < 65 µm and who received balanced salt solution for 30 s. Changes in endothelial cell density (ECD), central corneal thickness (CCT), coefficient of variation (CV), and hexagonality values were compared between the groups at 3 and 6 months after surgery. Results: The mean ± standard deviaiton (SD) age of the patients was 28.11 ± 6.56 years. The mean ± SD ECD did not change significantly in either group between the baseline and at 3 and 6 months postoperatively. The baseline mean ECD was significantly higher in group one than that in group two (P < 0.001) and remained so at 3 (P = 0.002) and 6 months (P = 0.022) postoperatively. The baseline hexagonality value was lower in group one (P = 0.173), with a gradual decrease during the postoperative follow-up as compared with that in group two (P = 0.016 and 0.001 at 3 and 6 months postoperatively, respectively). Group one had a significantly lower CCT at 3 and 6 months postoperatively (both P < 0.001) and a higher mean CV (3 months: P = 0.028; 6 months: P = 0.328). Conclusions: A single intraoperative application of MMC for 30 s as prophylaxis for corneal haze development during refractive surface ablation procedures had no significant effect on ECD up to 6 months postoperatively. Future studies with a contralateral-eye design (to neutralize factors specific to the individual patient), a larger sample size, and longer follow-up are necessary to confirm or disprove our observations

Presentation of research-oriented curriculum model for preschool period

Background and purpose: The present study was conducted with the aim of presenting a research-oriented curriculum model for the preschool period. Research method: In terms of practical goals and in terms of data, this research is mixed exploratory (qualitative-quantitative) and in terms of nature, in the qualitative dimension, the data of the foundation is of its kind, and in the quantitative dimension, it is a cross-sectional survey. The statistical population of the qualitative part includes university professors and experts in the field of educational sciences and psychology, and in the quantitative part, it consists of all managers and teachers of preschool centers in Tehran with a master's degree and above in the field of educational sciences, in the number of 300 people. The sampling method in the qualitative section was purposeful, snowball type, and 15 experts were selected, and we reached theoretical saturation. In the quantitative section, 169 people were selected based on Morgan's volume determination formula. In the current research, after the open and axial coding of the measurement tool, it was sent in the form of a set form and sent to the experts for selective coding and validated, and based on this, a researcher-made questionnaire was designed and distributed among the randomly selected statistical sample. . Then the collected data was analyzed using descriptive and inferential statistics. Findings: From the results of data analysis, 3 dimensions of structure, education and skills in 26 components of 142 indicators were finalized for the research-oriented curriculum model of preschool period and the results of factor analysis All three dimensions of structure, education and skill were confirmed (P=0.05). Conclusion: After the analysis of the results and its factor approval, the final approval and prioritization by experts, the dimensions, components and indicators of the model were drawn and the said model was again validated by the experts