The Aquaporin-1 Depletion Downregulates the Sclera Biomechanical Strength.

Purpose: To evaluate the relation of aquaporin-1 (AQP-1) expression and scleral biomechanical strength. Method: Guinea pigs with 3 weeks old received intravitreal injection of adeno-associated virus (AAV) containing AQP-1 or si-AQP-1 sequence, by which to up- or downregulate the AQP-1 expression in choroid. Animals were sacrificed 4 weeks after treatment. Then the expression of AQP-1 in the choroid was determined using western blotting, and the sclera stiffness recorded as Young's modulus was determined using tension test. The relation of AQP-1 expression and sclera stiffness was then analyzed. Results: Immunostaining revealed that AQP-1 protein expression was mainly observed in choroidal vascular endothelial cells layer. After the upregulation of AQP-1 expression, the scleral stiffness is slightly increased compared with that in control, but without significant difference. After the downregulation of AQP-1 expression, the scleral stiffness is lower than that in control group (p < .001). There is a positive relation between AQP-1 expression and sclera stiffness (p < .001). Conclusion: The present study revealed that the AQP-1 depletion downregulates the sclera biomechanical strength, which provides information for better understanding the mechanism of myopia development.

Management of Corneal Ectasia after LASIK with Phototherapeutic Keratectomy Combined with Photorefractive Keratectomy and Collagen Cross-Linking.

BACKGROUND: To evaluate the efficacy of phototherapeutic keratectomy (PTK) combined with photorefractive keratectomy (PRK) and riboflavin with ultraviolet-A collagen cross-linking (CXL), performed sequentially on the same day, in the management of corneal ectasia after LASIK. METHODS: This retrospective review comprised consecutive patients with corneal ectasia after LASIK. The patients were administered PTK and PRK on the previous corneal flap, and CXL was given on the same day by the same surgeon. The main outcome measures included age, sex, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent refraction, cylinder equivalent refraction, steep and flat keratometries (K), central corneal thickness (CCT), endothelial cell count, corneal haze, and ectasia stability. Mean follow-up period was 6, 12, and 24 months. RESULTS: Sixteen eyes of twelve patients were included in the study. Twenty-four months after administration of PTK combined with PRK and CXL, a significant improvement in UDVA was observed. Mean cylinder equivalent refraction was significantly reduced at 6, 12, and 24 months postoperatively. However, no significant reduction was observed in spherical equivalent refraction. A significant reduction in the flat K and steep K values was observed. No significant change in mean CCT value was observed. Mean endothelial cell count and morphology were unchanged between preoperative and postoperative patients. In addition, no obvious corneal haze was observed. CONCLUSIONS: PTK combined with PRK and CXL on the same day is a safe and effective treatment in improving visual acuity in selected patients with corneal ectasia after LASIK.

Corneal Collagen Crosslinking Combined with Phototherapeutic Keratectomy and Photorefractive Keratectomy for Corneal Ectasia after Laser in situ Keratomileusis.

PURPOSE: The aim of this study was to analyze the effects of corneal crosslinking (CXL) combined with phototherapeutic keratectomy (PTK) and photorefractive keratectomy (PRK) in halting the progression and improving the visual function of corneal ectasia after laser in situ keratomileusis (LASIK). METHODS: PTK-PRK-CXL was performed on 14 eyes of 14 patients who developed corneal ectasia after LASIK. The visual acuity, spherical refraction and cylinder, corneal topography indices, thinnest corneal thickness (TCT), and endothelial cell count were evaluated at baseline and at 1, 3, 6, and 12 months postoperatively. RESULTS: The mean uncorrected visual acuity improved significantly from 0.64 ± 0.36 logMAR preoperatively to 0.19 ± 0.12 logMAR at 12 months of follow-up (p < 0.001), while the mean best corrected visual acuity improved from 0.21 ± 0.14 logMAR at baseline to 0.04 ± 0.10 logMAR at 12 months postoperatively (p < 0.001). A significant decrease was observed in Kmax and Kmean values from 52.51 ± 6.74 and 43.55 ± 3.37 D at baseline to 45.72 ± 5.18 (p < 0.001) and 40.60 ± 3.05 D (p < 0.001) at the 1-year follow-up. The mean TCT decreased significantly from 419.07 ± 36.56 µm before treatment to 320.93 ± 39.78 µm at 12 months of follow-up (p < 0.001), and there was no significant endothelial cell loss (p > 0.05) beyond 6 months after treatment. CONCLUSION: PTK-PRK-CXL is a promising procedure to halt the progression of post-LASIK keratectasia with significant visual quality improvement.

Hydrogen peroxide promotes the expression of angiopoietin like 4 in RAW264.7 macrophages via MAPK pathways.

Previous studies including some vivo experiments and large scale clinical trials have indicated that angiopoietin like 4 (ANGPTL4) is involved in atherosclerosis. However, the specific mechanism underlying the process remains unresolved. Similarly, cumulative evidence indicated that hydrogen peroxide (H2O2) is closely related to the occurrence and development of atherosclerosis. The current study investigated whether H2O2 treatment can affect ANGPTL4 release in macrophage cells cell viability assay, western blot analysis, ELISA and immunofluorescence. It was determined that treatment with 0.25 and 0.5 mM H2O2 resulted in a significant increase in ANGPTL4 protein expression in macrophage cells. Mitogen­activated protein kinase (MAPK) pathways were implicated in the secretion of ANGPTL4 regulated by H2O2, and specific inhibitors of MAPK1 (also known as ERK) and p38 MAPK significantly decreased H2O2 induced ANGPTL4 protein expression. Accordingly, it was demonstrated that ANGPTL4 expression was regulated by H2O2 via ERK and p38 MAPK, but not the MAPK8 (also known as JNK) pathway. In view of the effects of H2O2 and ANGPTL4 on atherosclerosis, the influence of H2O2 on ANGPTL4 provided new insight into the mechanism of atherosclerosis.

Comparative study of visual acuity and aberrations after intralase femtosecond LASIK: small corneal flap versus big corneal flap.

AIM: To study the effect of different flap sizes on visual acuity, refractive outcomes, and aberrations after femtosecond laser for laser in situ keratomileusis (LASIK). METHODS: In each of the forty patients enrolled, 1 eye was randomly assigned to receive treatment with a 8.1mm diameter corneal flap, defined as the small flap, while the other eye was treated with a 8.6mm diameter corneal flap, defined as the big flap. Refractive errors, visual acuity, and higher-order aberrations were compared between the two groups at week 1, month 1 and 3 postoperatively. RESULTS: The postoperative refractive errors and visual acuity all conformed to the intended goal. Postoperative higher-order aberrations were increased, especially in spherical aberration (Z12) and vertical coma (Z7). There were no statistically significant differences between the two groups in terms of postoperative refractive errors, visual acuity, root mean square of total HOAs (HO-RMS), trefoil 30° (Z6), vertical coma (Z7), horizontal coma (Z8), trefoil 0° (Z9), and spherical aberration (Z12) at any point during the postoperative follow-up. CONCLUSION: Both the small and big flaps are safe and effective procedures to correct myopia, provided the exposure stroma meets the excimer laser ablations. The personalized size corneal flap is feasible, as we can design the size of corneal flap based on the principle that the corneal flap diameter should be equal to or greater than the sum of the maximum ablation diameter and apparatus error.