Assessing effects of mechanical stimulation of fluid shear stress on inducing matrix Metalloproteinase-9 in cultured corneal epithelial cells.

Blinking is regarded as mechanical stimulation of fluid shear stress on the corneal epithelial cells. Therefore, we evaluated whether fluid shear stress affects matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in cultured human corneal epithelial cells (HCECs). No other study has shown the influence of fluid shear stress on HCECs regarding mRNA expression and the protein levels of MMPs. Cultured HCECs were exposed to shear stress (0, 1.2, 12 dyne/cm2) for 12 and 24 h with the parallel-plate type of flow chamber. Gene expression of MMPs and TIMPs was measured by real-time polymerase reaction. Concentrations of MMP-1 and MMP-9 in cell lysates were determined using bead-based amplified luminescent proximity homogenous assay-linked immunosorbent assay. The expression of MMP-9 and MMP-1 in HCECs exposed to low and high flow for 12 and 24 h, respectively, increased significantly compared with those under static conditions. The expression of MMP-9 in the cells exposed to high flow for 24 h increased significantly compared with those under static and low flow conditions. Levels of MMP-9 in cell lysates exposed to fluid flow for 24 h were elevated significantly with increasing shear stress. Fluid shear stress exerted on HCECs affected MMPs, which was associated with inflammation and pathogenesis. Mechanical stress induced by blinking might influence expression of MMPs on the ocular surface. Further studies are warranted to establish the molecular mechanism of shear stress-induced alternations of MMPs.

Extracellular matrix gene expression in human trabecular meshwork cells following mechanical fluid flow stimulation.

AIM: To investigate changes in extracellular matrix (ECM) gene expression in human trabecular meshwork (HTM) cells in response to mechanical fluid flow stimulation. METHODS: HTM cells were grown on a glass plate coated with 0.02% type I collagen (COL) and exposed to shear stress (0, 0.2, 1.0 dyne/cm2) for 12h. Changes in genes related to the ECM were evaluated by real-time reverse transcriptase-polymerase chain reaction. Phosphorylation of Smad2 protein was investigated by Western blotting. RESULTS: After mechanical stimulation, COL type 4 alpha 2, COL type 6 alpha 1, and fibronectin-1 mRNA were significantly higher than the static control (P<0.05, <0.05, and <0.01, respectively). The metalloproteinase-2 and plasminogen activator inhibitor-1 mRNA were significantly higher than the static control (P<0.05 and <0.01, respectively), while the differences in the tissue inhibitors of metalloproteinases-2 mRNA were not significant. The phosphorylation of Smad2 levels was significantly higher compared to the static control cells. CONCLUSION: Changes in the expressions of genes associated ECM metabolism result in HTM cells after mechanical stimulation. The mechanical stimulation of the aqueous humor to the trabecular meshwork may promote ECM turnover and contribute to intraocular pressure homeostasis.

Effects of Diquafosol Ophthalmic Solution on Quality of Life in Dry Eye Assessed Using the Dry Eye-Related Quality-of-Life Score Questionnaire: Effectiveness in Patients While Reading and Using Visual Display Terminals.

PURPOSE: Diquafosol ophthalmic solution improves objective findings in the ocular surface and subjective symptoms in patients with dry eye. The Dry Eye-Related Quality-of-Life Score (DEQS) questionnaire was developed to assess dry eye symptoms and their effects on quality of life. However, because little research using the DEQS has been reported, we evaluated the effects of diquafosol ophthalmic solution on ocular surface findings and quality of life using the DEQS in patients with dry eye. METHODS: Sixty-three patients with dry eye were assigned to the control group (artificial tears) or diquafosol group. Both groups instilled 1 drop of the solution in both eyes 6 times daily and were evaluated after 2 weeks; the diquafosol group also was instructed to be examined at 1 and 3 months. We evaluated the subjective symptoms using the DEQS, fluorescein staining score, tear film breakup time (BUT), Schirmer testing, and lower tear meniscus height with anterior-segment optical coherence tomography. RESULTS: In the diquafosol group, the fluorescein staining score, BUT, tear meniscus height, and DEQS scores improved significantly compared with before treatment in contrast to the control group. Furthermore, in the diquafosol group, the staining score and BUT improved significantly compared with the control group. Analysis of each DEQS item indicated that diquafosol ophthalmic solution relieved foreign body sensation and problems when reading and using visual display terminals compared with the control group. CONCLUSIONS: Diquafosol ophthalmic solution was effective in patients with dry eye, especially those with foreign body sensation and problems when reading and using visual display terminals.

Amniotic Membrane Transplantation for Corneal and Conjunctival Diseases: Classification of Application and Outcomes from Analysis of 95 cases.

Purpose: To evaluate the indications and outcomes of amniotic membrane (AM) transplantation for corneal and conjunctival diseases. Subjects and methods: Ninety-five eyes of ninety patients who underwent AM transplantation between January 2007 and May 2016 were included in this study. The surgical procedures, diagnosis and postoperative outcomes were investigated retrospectively. Results: Transplantation was conducted in three surgical procedures. AM patch, for the promotion of corneal re-epithelialization, was performed in 14 cases with persistent epithelial defects. Thirteen cases healed with total epithelialization. Corneal perforation was noted in Stevens-Johnson syndrome and cured with keratoplasty. AM graft for basement membrane supply, was performed in 72 cases. Of these, 32 cases had been followed for at least one year after AM graft out of which pterygium recurred at one year in 5. Conjunctival tumor recurred in 3 out of 17 cases, and was treated with a repeated of AM graft. AM stuff for substrate supply to the deep corneal layer, was performed in 9 cases with corneal perforation. Leakage of aqueous humor was cured in all 9 cases. Seven cases had keratoplasty performed after the AM stuff and recovered completely. The other 2 cases were observed without additional surgery. There were no complications due to the AM transplantation during the course of treatment in any of the 95 cases. Conclusion: AM transplantation is applied in three different procedures. Each of these was effective in achieving the corneal and conjunctival reconstruction designed for it.

Transforming Growth Factor-ß Signaling Cascade Induced by Mechanical Stimulation of Fluid Shear Stress in Cultured Corneal Epithelial Cells.

Purpose: Because blinking is regarded as mechanical stimulation of fluid shear stress on the corneal epithelial cells, we investigated the effects of fluid shear stress on cultured human corneal epithelial cells (HCECs). Methods: The HCECs were exposed to shear stress (0, 1.2, 12 dyne/cm2) with the parallel-plate type of flow chamber. Wound healing, cellular proliferation, growth factor expression, TGF-ß1 concentration in the culture supernatant, and phosphorylation of SMAD2 were investigated. Results: Monolayers of HCECs exposed to shear stress had delayed wound healing and decreased proliferation compared with those of the static control (0 dyne/cm2). With increasing shear stress, TGF-ß1 expression and phosphorylation of SMAD2 increased significantly, but the levels of total TGF-ß1 in the culture supernatant decreased significantly. Delayed wound healing, decreased proliferation, and phosphorylation of the SMAD2 by shear stress were canceled out with a TGF-ß receptor inhibitor. Conclusions: Fluid shear stress on the HCECs affected TGF-ß signaling, which was associated with delayed wound healing. Mechanical stress by blinking might involve TGF-ß signaling, and activation of TGF-ß might be a key factor in wound healing of the corneal epithelium. Further studies should investigate the molecular mechanism of shear stress-induced activation of TGF-ß.

Comparison of effect of nepafenac and diclofenac ophthalmic solutions on cornea, tear film, and ocular surface after cataract surgery: the results of a randomized trial.

BACKGROUND: The aim of this study was to compare the effects of nepafenac ophthalmic suspension 0.1% (Nevanac) and diclofenac sodium ophthalmic solution 0.1% (Diclod) on the cornea, tear film, and ocular surface after cataract surgery. METHODS: A total of 60 eyes (60 patients) were selected for this study, with no ocular diseases other than cataract (scheduled for cataract surgery by one surgeon). Patients were randomly enrolled to receive nepafenac or diclofenac in the perioperative period, and cataract surgery was performed using torsional microcoaxial phacoemulsification and aspiration with intraocular lens implantation via a transconjunctival single-plane sclerocorneal incision at the 12 o'clock position. We compared intra- and intergroup differences preoperatively and postoperatively in conjunctival and corneal fluorescein staining scores, tear film breakup times, Schirmer's tests, the Dry Eye Related Quality of Life Scores, and tear meniscus areas using anterior segment optical coherence tomography. RESULTS: The diclofenac group had significantly higher conjunctival and corneal fluorescein staining scores at 4 weeks postoperatively compared with the nepafenac group (P<0.001). Within the diclofenac group, significantly higher conjunctival and corneal fluorescein staining scores were noted at 4 weeks postoperatively than those seen preoperatively (P<0.001) and at 1 week postoperatively (P<0.001). No statistically significant differences were found in any other items. CONCLUSIONS: Nepafenac ophthalmic suspension 0.1% is considered safe for the corneal epithelium after cataract surgery.

Imaging of the Corneal Subbasal Whorl-like Nerve Plexus: More Accurate Depiction of the Extent of Corneal Nerve Damage in Patients With Diabetes.

PURPOSE: To show that noninvasive in vivo corneal confocal microscopy (IVCM) can make more accurate imaging of the corneal subbasal nerve plexus possible. This diagnostic technique monitors the status of diabetic peripheral neuropathy. However, it is difficult to accurately confirm the corneal area captured by IVCM, which can induce measurement errors. Because the whorl-like characteristic pattern of the corneal subbasal nerve plexus is in the inferocentral cornea, we evaluated whether IVCM images of the whorl-like patterns can accurately evaluate the corneal nerve fibers in diabetic neuropathy. METHODS: Forty-seven patients with diabetes (DM group) and 21 healthy control subjects underwent IVCM examination to compare the characteristics of the corneal subbasal nerve plexus around the central cornea (conventional method) and the whorl-like pattern in the inferocentral cornea (study method). We measured the total corneal nerve fiber and branch length (CNFL). RESULTS: The total CNFL were significantly shorter in the DM group than in the control group and tended to decrease with progression of diabetic retinopathy, nephropathy, neuropathy, and decreased corneal sensation. There was a significant positive correlation between the CNFL values obtained with the conventional method and those obtained with the study method. The coefficient of variation of the CNFL values in the study method was significantly smaller than in the conventional method. CONCLUSIONS: Our findings indicated that IVCM measurements of the whorl-like patterns may accurately define the extent of corneal nerve damage in order to monitor diabetic peripheral neuropathy.

Wound healing process after corneal stromal thinning observed with anterior segment optical coherence tomography.

PURPOSE: The aim of this study was to observe the wound healing process after corneal stromal thinning by using anterior segment optical coherence tomography (AS-OCT) and a slit lamp. METHODS: Four patients with corneal stromal thinning (2 patients: corneal iron foreign bodies; 2 patients: keratitis) were included. Serial AS-OCT and slit-lamp examinations were used to follow up the progress of these patients. The thicknesses of the whole cornea and the corneal stroma were measured with AS-OCT and compared with the findings observed during the slit-lamp examination. RESULTS: AS-OCT showed that epithelial hypertrophy and hyperplasia initially occurred in the area of the corneal stromal thinning; subsequently, scar tissue formed in the area with an improvement in the thickness of the corneal stroma. This wound healing process was observed in all 4 patients. The scar tissue initially appeared opaque on slit-lamp examination and was characterized by a high signal produced on AS-OCT, which was different from the normal corneal stroma. The scar tissue gradually appeared clear on slit-lamp examination; however, the high signal on AS-OCT remained. CONCLUSIONS: AS-OCT can be used to detect the wound healing process of corneal stromal thinning.