Self-limited corneal ectasia in a post-LASIK eye after cataract surgery: A case report.

INTRODUCTION: To present a case with a history of laser in situ keratomileusis (LASIK) developing central conic protrusion after phacoemulsification cataract surgery, which spontaneously resolved 5 months postoperatively. PATIENT CONCERNS: A 55-year-old female who underwent myopic LASIK surgery 10 years ago presented to the clinic with bilateral cataracts and without ectasia. Following phacoemulsification cataract surgery and intraocular lens implantation in the right eye, the patient experienced a significant increase in spherical equivalent and corneal astigmatism. DIAGNOSES: Based on a central conic protrusion on topography examination, surgically-induced corneal ectasia was diagnosed. INTERVENTIONS: Topical lubricants, corticosteroids, and serial follow-up with corneal topography. OUTCOMES: The corneal protrusion gradually resolved over a period of 5 months. LESSONS: For post-LASIK patient who developed corneal protrusion following uneventful cataract surgery with a clear corneal incision, the clear corneal wound may have disrupted the biomechanical stability of the post-LASIK eye, compromising the peripheral stromal integrity. Additionally, postoperative inflammation could have contributed to corneal ectasia. Smaller clear corneal wounds or scleral tunnel entry during cataract surgery in post-LASIK eyes should be considered. Monitoring wound healing and using topical steroids can aid in achieving satisfactory outcomes and reducing the potential vision-threatening complications associated with corneal ectasia.

Diffuse lamellar keratitis as a rare complication of diamond burr superficial keratectomy for recurrent corneal erosion: a case report.

BACKGROUND: To present a case with a history of laser in situ keratomileusis (LASIK) developing diffuse lamellar keratitis (DLK) after diamond burr superficial keratectomy (DBSK) for recurrent corneal erosion (RCE). CASE PRESENTATION: A 25-year-old man presented with multiple episodes of RCE one year after femtosecond-assisted LASIK for myopia correction. Because conservative treatments failed to halt the repetitive attack of RCE, he underwent epithelial debridement and DBSK. However, severe foreign body sensation and blurred vision developed on postoperative day one. The next day, slit lamp biomicroscopy revealed DLK manifested as diffuse granular infiltrates at the flap interface. After topical corticosteroid treatment, the inflammation resolved gradually, and his vision recovered to 20/20. CONCLUSIONS: Diffuse lamellar keratitis is a rare post-LASIK complication that can be triggered by DBSK, which causes impairment of the corneal epithelial integrity and subsequent inflammation at the flap interface. For post-LASIK patients with RCE, alternative treatments, such as anterior stromal puncture, may be considered to avoid extensive disruption of corneal epithelium and DLK development depending on the size and the location of the lesions.

Low ambient temperature correlates with the severity of dry eye symptoms.

PURPOSE: The symptoms of dry eye disease (DED) are influenced by environmental factors, but the effect of ambient temperature is less certain. Our purpose was to investigate the relationship between the severity of DED symptoms and the ambient temperature. MATERIALS AND METHODS: This retrospective study reviewed the symptom scores, including ocular surface disease index (OSDI) and standardized patient evaluation of eye dryness (SPEED), as well as tear film parameters of first-time DED patients between June 2018 and June 2019. The contribution of tear film parameters and environmental factors, including ambient temperature, humidity, wind speed, and the concentration of air pollutants, to the severity of dry eye symptoms was evaluated by univariate and multivariate linear regression analyses. RESULTS: There were 351 patients included aged 52.8 ± 13.6 years, and 257 (73.2%) were female. The average tear film break-up time, Schirmer test value, and lipid layer thickness were 2.6 ± 0.7 s, 5.5 ± 4.3 mm, and 64.1 ± 6.0 µm, respectively. The average OSDI and SPEED were 41.8 ± 19.8 and 12.1 ± 5.1, respectively. In winter, the patients reported higher OSDI and SPEED. Both scores were significantly correlated with low ambient temperature. Regression analysis showed that low ambient temperature and Schirmer test value contributed to higher OSDI, while low ambient temperature and younger age contributed to higher SPEED. CONCLUSION: Low ambient temperature plays a significant role in DED symptom severity.

Inhibition of Rho-associated protein kinase activity enhances oxidative phosphorylation to support corneal endothelial cell migration.

Corneal endothelial cell (CEC) dysfunction causes corneal edema and severe visual impairment that require transplantation to restore vision. To address the unmet need of organ shortage, descemetorhexis without endothelial keratoplasty has been specifically employed to treat early stage Fuchs endothelial corneal dystrophy, which is pathophysiologically related to oxidative stress and exhibits centrally located corneal guttae. After stripping off central Descemet's membrane, rho-associated protein kinase (ROCK) inhibitor has been found to facilitate CEC migration, an energy-demanding task, thereby achieving wound closure. However, the correlation between ROCK inhibition and the change in bioenergetic status of CECs remained to be elucidated. Through transcriptomic profiling, we found that the inhibition of ROCK activity by the selective inhibitor, ripasudil or Y27632, promoted enrichment of oxidative phosphorylation (OXPHOS) gene set in bovine CECs (BCECs). Functional analysis revealed that ripasudil, a clinically approved anti-glaucoma agent, enhanced mitochondrial respiration, increased spare respiratory capacity, and induced overexpression of electron transport chain components through upregulation of AMP-activated protein kinase (AMPK) pathway. Accelerated BCEC migration and in vitro wound healing by ripasudil were diminished by OXPHOS and AMPK inhibition, but not by glycolysis inhibition. Correspondingly, lamellipodial protrusion and actin assembly that were augmented by ripasudil became reduced with additional OXPHOS or AMPK inhibition. These results indicate that ROCK inhibition induces metabolic reprogramming toward OXPHOS to support migration of CECs.

Predictability of 6 Intraocular Lens Power Calculation Formulas in People With Very High Myopia.

Purpose: To investigate the accuracy of 6 intraocular lens (IOL) power calculation formulas in predicting refractive outcomes in extremely long eyes. Setting: Department of Ophthalmology, Far Eastern Memorial Hospital, Taiwan. Design: Retrospective comparative study. Methods: In this retrospective single-center study, we reviewed 70 eyes of 70 patients with axial length (AL) ≥ 28 mm who had received an uneventful 2.2 mm corneal wound phacoemulsification and in-the-bag IOL placement. The actual postoperative refractive results were compared to the predicted refraction calculated with 6 formulas (Haigis, Hoffer Q, Holladay 1, SRK/T, T2, Barrett Universal II formulas) using IOLMaster 500 as optical biometry in the User Group for Laser Interference Biometry (ULIB) constants. Results: Overall, the Haigis and Barrett formulas achieved the lowest level of mean prediction error (PE) and median absolute error (MedAE). Hoffer Q, Holladay 1, SRK/T, and T2 had hyperopic prediction errors (p < 0.05). The Hoffer Q and Holladay 1 had significantly more MedAE between the 6 formulas. After the mean PE was zeroed out, the MedAE had no significant difference between each group. The absolute error tends to be larger in patients with longer AL. The absolute errors were 30.0-37.1% and 60.0-64.3% within 1.0 D of all patients compared to predicted refraction calculated using various formulas. Conclusion: The Haigis and Barrett Universal II formulas had a better success rate in predicting IOL power in high myopic eyes with AL longer than 28 mm using the ULIB constant in this study. The postoperative refractive results were inferior to the benchmark standards, which indicated that the precision of IOL power calculation in patients with high myopia still required improvement.

Comparison of Intravitreal Dexamethasone Implant and Ranibizumab in Vitrectomized Eyes with Diabetic Macular Edema.

PURPOSE: This retrospective study aimed to compare the efficacy of intravitreal ranibizumab (IVR) and intravitreal dexamethasone implant (IDI) for pseudophakic vitrectomized eyes with diabetic macular edema (DME) in a single institution. METHODS: Pseudophakic vitrectomized eyes with treatment-naïve center-involved DME were enrolled, with one eye in each patient. They were divided into two groups: one group receiving IDI every 3 to 4 months and another group receiving IVR using 3 monthly plus treat-and-extend injections, all with monthly follow-up for 6 months. Switch of intravitreal drugs or deferred macular laser was not allowed. Primary outcome measures included change in central foveal thickness (CFT) in 1 mm by spectral-domain optical coherence tomography and best-corrected visual acuity (BCVA) at Month 6. RESULTS: Twenty-two eyes were included in the IDI group and 26 eyes in the IVR group. The baseline demographics, glycosylated hemoglobin level, intraocular pressure (IOP), BCVA, and CFT did not significantly differ (p > 0.05). Compared to baseline data, CFT decreased and BCVA improved significantly after either IDI or IVR at Month 6 (p < 0.05). Significantly better mean final BCVA (0.38 logMAR vs. 0.62 logMAR, p=0.04), more mean visual gain (-0.30 logMAR vs. -0.15 logMAR, p=0.02), lower mean final CFT (310.9 µm vs. 384.2 µm, p=0.04), and larger mean CFT decrease (-150.0 µm vs. -60.1 µm, p=0.03) were found in the IDI group compared to those in the IVR group. A smaller mean treatment number (2.6 vs. 5.6, p < 0.001) and higher rate of postinjection ocular hypertension requiring topical hypotensive agent therapy (27.3% vs. 0%, p=0.0002) were demonstrated in the IDI group than those in the IVR group. CONCLUSION: We concluded that IDI and IVR can both effectively treat vitrectomized eyes with DME. Dexamethasone implants had significantly better visual/anatomical improvement, smaller treatment number, and higher rate of elevated IOP after injection than IVR in pseudophakic vitrectomized eyes with DME in a 6-month period.

Characteristics of tear film lipid layer in young dry eye patients.

BACKGROUND/PURPOSE: To investigate the characteristics of subjective symptoms and objective parameters among young patients with dry eye disease (DED) and compare them with those of older patients. METHODS: We retrospectively enrolled 675 patients with DED who were divided into three age groups (20-41 years [younger], 41-60 years [middle], and >60 years [older]) (n = 143, 304, and 228, respectively). Subjective symptoms were evaluated using Standardized Patient Evaluation of Eye Dryness (SPEED) and Ocular Surface Disease Index (OSDI) questionnaires. Aqueous tear secretion was evaluated with the Schirmer test II. The number of expressible meibomian glands was evaluated with a slit-lamp-aided standardized evaluator. Lipid layer thickness (LLT), blink/incomplete blink rates and meibography were measured with the LipiView® II interferometer. The extent of the meibomian gland dropout was graded using a meiboscale. RESULTS: The younger age group had higher subjective symptom severity, as reflected by higher SPEED (p < 0.001) and OSDI scores (p = 0.051). The SPEED scores negatively correlated with LLT in all patients (r = -0.136, p < 0.001). Younger patients also had thinner average LLT (p < 0.001), lower meiboscale (p < 0.001) and a higher number of expressible meibomian glands (p < 0.001). Additionally, they had significantly more total blinks (p < 0.001), incomplete blinks (p < 0.001), and incomplete blink rate (p = 0.006). CONCLUSION: Manifestations of DED vary with age. In our cohort, younger age patients had more symptoms and blinks, which may have resulted from thinner LLT as the structure and function of the meibomian glands were affected less than in middle and older age patients.

Exploring a peptidomimetic approach of N-cadherin in modulating fibroblast growth factor receptor signaling for corneal endothelial regeneration.

Endothelial rejection and a critical shortage of corneal transplants present an unmet medical need in corneal regeneration research area. Although basic fibroblast growth factor (bFGF) is a potent mitogenic factor for corneal ex vivo expansion, it is also a morphogen eliciting unfavorable endothelial-mesenchymal transition (EnMT) of corneal endothelial cells. A pharmacological reagent that retains the beneficial proliferative effect while lacking the EnMT effect of bFGF would be of great potential in corneal regeneration. In present study, we demonstrated that bFGF not only activated the canonical fibroblast growth factor receptor 1 (FGFR1) tyrosine kinase pathway, but also further upregulated matrix metalloproteinase activity to cleave N-cadherin into N-terminus and C-terminus fragments, which activated the classical FGFR1 tyrosine kinase pathway and a cryptic ß-catenin pathway to affect corneal proliferation and EnMT, respectively. We generated the synthetic peptides resembling a critical motif in the ectodomain of N-cadherin and found these peptides enhanced downstream proliferative signaling of FGFR1 but without seemingly EnMT effect. The potential of these peptides can be demonstrated on both ex vivo cell culture and in vivo rat cryo-injury model. Our study indicated this peptidomimetic approach of N-cadherin can stimulate corneal regeneration and offer a promising therapeutic option to treat corneal endothelial dysfunction.

Mitomycin C modulates intracellular matrix metalloproteinase-9 expression and affects corneal fibroblast migration.

Mitomycin C (MMC) is often used to prevent postoperative corneal haze and subconjunctival fibrosis in ocular surgery. It also affects the motility and viability of the residual ocular cells, including corneal stromal cells. Extracellular matrix metalloproteinase-9 (MMP-9) contributes to the promotion of cell movement in macrophage and cancer cells, but the intracellular role of MMP-9 remained unclear. Herein, we illustrated the novel role of intracellular MMP-9 in MMC-suppressed cell migration using isolated human corneal fibroblasts (HCFs). In HCFs, MMC enhanced intracellular MMP-9 at transcriptional and protein levels. Using co-immunoprecipitation analysis, we confirmed that MMC enhanced the association between intracellular MMP-9 and inactive FAK/paxillin (PXN) complexes, i.e. PXN without phospho-tyrosine 118 (pY118) and FAK without phospho-tyrosine 397 (pY397). To verify the role of intracellular MMP-9 in migration, its gene was directly isolated from HCFs and highly expressed in HCFs by a lentivirus-based pseudovirus system with encephalomyocarditis virus (EMCV)-driven enhanced green fluorescent protein (GFP) as the MMP-9-IG-versus IG-expressing cells. Compared with the IG-expressing cells, higher intracellular MMP-9 expression in the MMP-9-IG-expressing HCFs proliferated and migrated more slowly. Phosphorylation of FAK at Y397 and PXN at both Y31 and Y118 were significantly less in the MMP-9-IG-expressing HCFs. These suggested that MMC-upregulated intracellular MMP-9 clutched inactive FAK/PXN complexes at focal adhesion sites to form a new "inactive" trimer, prohibited FAK/PXN complexes phosphorylation and retarded corneal fibroblast migration.

Targeting non-muscle myosin II promotes corneal endothelial migration through regulating lamellipodial dynamics.

Corneal endothelial cell (CEC) dysfunction causes corneal edema that may lead to blindness. In addition to corneal transplantation, simple descemetorhexis has been proposed to treat centrally located disease with adequate peripheral cell reserve, but promoting the centripetal migration of CECs is pivotal to this strategy. Here, we show that targeting non-muscle myosin II (NMII) activity by Y27632, a ROCK inhibitor, or blebbistatin, a selective NMII inhibitor, promotes directional migration of CECs and accelerates in vitro wound healing. The lamellipodial protrusion persistence is increased, and actin retrograde flow is decreased after NMII inhibition. Counteracting lamellipodial protrusion by actin-related protein 2/3 (ARP2/3) inhibitor abolishes this migration-promoting effect. Although both Y27632 and blebbistatin accelerate wound healing, cell junctional integrity and barrier function are better preserved after blebbistatin treatment, leading to more rapid corneal deturgescence in rabbit corneal endothelial wounding model. Our findings indicate that NMII is a promising therapeutic target in the treatment of CEC dysfunction. KEY MESSAGES: NMII inhibition promotes directional migration and wound healing of CECs in vitro. Lamellipodial protrusion persistence is increased after NMII inhibition. Selective NMII inhibitor preserves junctional integrity better than ROCK inhibitor. Selective NMII inhibitor accelerates corneal deturgescence after wounding in vivo.

Isotopic dilution assay development of nisin A in cream cheese, mascarpone, processed cheese and ripened cheese by LC-MS/MS method.

The current food safety concern for food integrity demands the availability of an accurate, easy and reliable analytical tool for assay development of nisin A in cheese. To address this, we report the application of isotopically labelled peptide sequence MSTKDFNLDLVSVSKKDSGASP(R) (without thioether bridges) as internal standard for determination of nisin A in cream cheese, mascarpone, processed cheese and ripened cheese without the need for matrix-matched calibration by triple-quadrupole mass spectrometry. Full method validation was performed according to the modified Commission Decision 2002/657/EC criteria and method robustness was checked on 10 random cheese samples. Internal standard provided significant improvement (p < 0.05) in method precision for determination of nisin A in all four types of cheese. Significant losses (p < 0.05) for Nisin A in cheese was observed one week later. A fit-for-purpose method using internal standard procedure for accurate quantitation of Nisin A in cheese becomes available.

Evaluation of Patent Blue as the Vital Dye in an Animal Model of Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To evaluate the safety and feasibility of patent blue (PB) as the vital dye in Descemet membrane endothelial keratoplasty (DMEK). METHODS: Bovine corneal endothelial cells were incubated with different concentrations (0.02%-2.5%) of PB. The cell viability, which was assessed by Cell Counting Kit-8 assay, was compared with that of untreated control and 0.06% to 0.4% trypan blue. The dyes were also used for graft preparation and implantation in the porcine eye model to evaluate stain quality, dye retention, and the feasibility of using PB in DMEK surgery. RESULTS: No obvious increase in cytotoxicity was detected for 0.06% to 0.4% trypan blue and PB at concentrations up to 1.0%, but the cell viability after incubating with 1.5% to 2.5% PB was significantly reduced. PB at 0.5% to 1.0% generated good staining quality that can be used to facilitate graft implantation. Although the staining quality of 0.5% to 1.0% PB faded to an intermediate level after a 30-minute wash in phosphate-buffered saline, dye retention persisted for up to 24 hours. CONCLUSIONS: PB at 0.5% to 1.0% is biocompatible and can stain the graft sufficiently, making it an alternative for DMEK surgery.

Infrared thermography in the evaluation of meibomian gland dysfunction.

BACKGROUND/PURPOSE: To evaluate meibomian gland dysfunction (MGD) by infrared thermography. METHODS: An observational study was conducted at the Department of Ophthalmology, Far Eastern Memorial Hospital, New Taipei City, Taiwan. Participants included 89 MGD patients (30 in Grade 1, 49 in Grade 2, and 10 in Grade 3) and 65 controls. The close-eye thermographic images of the eyelid were obtained noninvasively by infrared thermography. Temperatures at 8 regions of interest (ROIs) of the eyelid margin and a reference temperature at the center of the upper eyelid were measured. The temperature ratio was defined as the temperature of ROI divided by the reference temperature. RESULTS: Eyelid margin temperature measured by infrared thermography increased from temporal side (ROI 1) to the nasal side (ROI 8) of the eye in both MGD patients and control groups. The temperature ratios were significantly higher in MGD participants than in controls, especially at ROI 8. CONCLUSION: The eyelid margin temperature measured by infrared thermography was higher in MGD participants. Further development of this infrared thermography system may become a rapid and non-invasive tool for MGD screening.

In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition.

Corneal endothelial cells (CECs) play a crucial role in maintaining corneal clarity through active pumping. A reduced CEC count may lead to corneal edema and diminished visual acuity. However, human CECs are prone to compromised proliferative potential. Furthermore, stimulation of cell growth is often complicated by gradual endothelial-mesenchymal transition (EnMT). Therefore, understanding the mechanism of EnMT is necessary for facilitating the regeneration of CECs with competent function. In this study, we prepared a primary culture of bovine CECs by peeling the CECs with Descemet's membrane from the corneal button and demonstrated that bovine CECs exhibited the EnMT process, including phenotypic change, nuclear translocation of ß-catenin, and EMT regulators snail and slug, in the in vitro culture. Furthermore, we used a rat corneal endothelium cryoinjury model to demonstrate the EnMT process in vivo. Collectively, the in vitro primary culture of bovine CECs and in vivo rat corneal endothelium cryoinjury models offers useful platforms for investigating the mechanism of EnMT.

Inhibition of matrix metalloproteinase activity reverses corneal endothelial-mesenchymal transition.

Ex vivo culture or regeneration of corneal endothelial cells often is subjected to gradual endothelial-mesenchymal transition and loss of function. Here, we found that during ex vivo culture, bovine corneal endothelial cells underwent endothelial-mesenchymal transition and had an up-regulated expression and activity of matrix metalloproteinases. Inhibition of matrix metalloproteinase activity in confluent bovine corneal endothelial cells decreased the level of endothelial-mesenchymal transition regulators: snail and slug. The phosphorylation and degradation of the key Wnt signaling pathway modulator active ß-catenin also were accelerated with the broad-spectrum matrix metalloproteinase inhibitor Marimastat, which may result from decreased N-cadherin shedding and increased intact N-cadherin molecules on the cell membrane. Intracameral injection of Marimastat also suppressed basic fibroblast growth factor-induced endothelial-mesenchymal transition in a rat corneal endothelium cryo-injury model and significantly diminished the corneal edema. Our study indicated that inhibition of matrix metalloproteinase activity can reverse endothelial-mesenchymal transition and preserve the function of corneal endothelial cells both during ex vivo culture and in vivo. This may offer a potential therapeutic target in regenerative medicine for the treatment of corneal endothelial dysfunctions.

Phenotypes of trypsin- and collagenase-prepared bovine corneal endothelial cells in the presence of a selective Rho kinase inhibitor, Y-27632.

PURPOSE: To optimize isolation of viable bovine corneal endothelial cells (BCECs), we evaluated the effectiveness of various preparation protocols. This entailed comparing the effects of collagenase A and trypsin in the presence and absence of a Rho kinase inhibitor, Y-27632, on proliferation and tight junctional and cytoskeletal integrity during their expansion. METHODS: 5-bromo-2'-deoxyuridine (BrdU) incorporation evaluated cell proliferation. Western blot analysis evaluated F-actin, zonule occludin, and ZO-1 associated nucleic acid binding protein (ZONAB) and RhoA expression. Rho A pulldown assay evaluated Rho A activity. RESULTS: In the trypsin (TrypLE)-prepared BCECs, BrdU incorporation decreased whereas nuclear ZONAB expression increased and became stable from day 3 to 7. In contrast, in the collagenase-A-prepared BCECs, we observed preserved ZO-1 integrity, invariant nuclear ZONAB expression, and dense cortical F-actin expression, and BrdU incorporation was invariant from days 1 to 7. Y-27632 did not increase BrdU incorporation and nuclear ZONAB expression in the TrypLE-prepared and the collagenase-A-prepared BCECs. Moreover, Y-27632 increased irregular cellular morphology and downregulated the expression of ZO-1 in the collagenase-A-prepared BCECs from days 1 to 7. Y-27632 inhibited RhoA activation irrespective of whether the cells were isolated with trypsin or collagenase A. CONCLUSIONS: It is preferable to isolate BCECs with collagenase A and expand them without Y-27632. With this protocol, proliferative activity and tight junctional and cytoskeletal integrity are better preserved than if trypsin is used in the presence or absence of Y-27632.

Correlations among ocular surface temperature difference value, the tear meniscus height, Schirmer's test and fluorescein tear film break up time.

PURPOSE: To report the use of a thermographer for measuring ocular surface temperature, and to evaluate the correlation among the obtained temperature difference values (TDVs) and dry eye parameters (tear meniscus height (TMH); Schirmer's test results; fluorescent tear breakup time (FTBUT)). METHODS: Forty-three participants (age 40.2±14.7 years; range 21-67 years) from Far Eastern Memorial Hospital, Taiwan were recruited for the study. The surface temperature was measured at the centre of the ocular surface for 4 s after blinking. TDV was defined as the change in corneal surface temperature relative to that of the preceding eye opening, where TDV01, TDV02, TDV03, and TDV04 represent the values obtained 1, 2, 3, and 4 s after blinking, respectively. Anterior segment optical coherence tomography (AS-OCT) was employed to measure the lower TMH. Schirmer's test with topical anaesthetic was conducted to measure the basal tear secretion. The FTBUT was recorded using a digital camera. RESULTS: TDV measurement exhibited high reliability (intraclass correlation coefficient=0.91). TDV03 exhibited the highest significance and strongest positive correlation with the TMH (r=0.52, p=0.0003) and Schirmer's test value (r=0.39, p=0.008), whereas the TDV03-FTBUT correlation was non-significant. Age correlated negatively and significantly with the TDV (r= -0.35, p=0.021), TMH (r= -0.33, p=0.031), and Schirmer's test value (r= -0.31, p=0.044). TDV03 remained significantly correlated with the TMH and Schirmer's test value after adjustment for age. CONCLUSIONS: The thermographer was effective in capturing temperature changes in the ocular surface. The temperature difference 3 s after blinking appears to be correlated with lower TMH and Schirmer test values.

Dexamethasone modifies mitomycin C-triggered interleukin-8 secretion in isolated human Tenon's capsule fibroblasts.

Intraoperative mitomycin C (MMC) is widely used to prevent pterygium recurrence and glaucoma filtering bleb failure, but it has been shown to induce corneal inflammation and cell death. Postoperative dexamethasone (DEX) is advocated to reduce MMC-related inflammation and cell death in corneal fibroblasts. Nevertheless, its long-term regulation mechanism in Tenon's capsule remains to be explored. The purpose of this study was to investigate how DEX modifies MMC's effects in human Tenon's capsule fibroblasts (HTFs). HTFs isolated from the pterygium surgical patients (n = 6) were treated with MMC at 0, 0.1, 0.2, and 0.4 mg/ml for 5 min and incubated in DEX at 10 µM for 0, 1, 2, and 3 days. Recombinant interleukin-8 (IL-8) was used to verify the effect of MMC-related IL-8 secretion. Cell proliferation of all the treated cells was analyzed by WST-1 assay. The amount of IL-8 secretion in HTFs was determined by enzyme-linked immunosorbent assay. Immunoblotting assay was used to analyze the expression of peroxisome-proliferator-activated receptor gamma (PPARγ) and B-cell lymphoma-extra large (Bcl-xL). Our results revealed that MMC significantly reduced the HTF cell proliferation rate. Additionally, MMC significantly upregulated IL-8 secretion in HTFs concentration-dependently. At 3 days post treatment (dpt), 5-min exposures to 0.1, 0.2, and 0.4 mg/ml MMC resulted in 1.4-fold (p = 0.012), 1.6-fold (p = 0.012), and 2.5-fold (p = 0.001) increases of IL-8 secretion. In contrast, DEX reversed the MMC-retarded cell proliferation rate (p = 0.036) and repressed MMC-related IL-8 secretion by 33.5% at 3 dpt (p = 0.003). Addition of recombinant IL-8 noticeably suppressed HTF cell proliferation in a concentration-dependent manner. DEX stimulated upregulation of both PPARγ and Bcl-xL at 1 dpt in normal HTFs and at 2 dpt in MMC-treated HTFs. PPARγ silencing reduced expression of PPARγ and Bcl-xL, but enhanced IL-8 secretion (p < 0.001). On the other hand, Bcl-xL silencing enhanced IL-8 secretion (p < 0.001), but did not affect PPARγ expression. These revealed that IL-8 secretion in HTFs is modulated by PPARγ-dependent Bcl-xL signaling. We conclude that DEX reversed the MMC-inhibited HTF cell proliferation via diminishing the MMC-induced IL-8 secretion, which resulted from a late-phase upregulation of the PPARγ and Bcl-xL. These long-term effects suggest a beneficial postoperative DEX treatment following intraoperative MMC application.

Enhanced corneal wound healing with hyaluronic acid and high-potassium artificial tears.

BACKGROUND: The aim of this study was to investigate the therapeutic role of preservative-free artificial tears containing hyaluronic acid and high potassium ion concentration (HA/high-K artificial tears) on mechanically scraped or alkali-induced corneal epithelial defects in rats. METHODS: We created mechanically scraped epithelial defects on the corneas of 24 Sprague-Dawley (SD) rats (three groups of eight rats) and alkali-induced epithelial defects on the corneas of 27 SD rats (three groups of nine rats). Then we applied topical 0.3 per cent or 0.15 per cent HA/high-K artificial tears four times daily for 1.5 days and compared its effect with that of topical phosphate buffered saline (PBS). The fluorescein staining analysis and histological examination were performed immediately after and at 12, 24 and 36 hours after injury. RESULTS: In the mechanical scraping model, the areas of fluorescein staining in the eyes after topical application of 0.3 per cent HA/high-K artificial tears were significantly smaller than those after PBS treatment at 12 and 24 hours after injury. At 36 hours, the staining areas of both 0.3 per cent and 0.15 per cent HA/high-K artificial tears-treated eyes were found to be significantly smaller than those of the PBS-treated eyes. In the alkali burn model, the promotion of corneal epithelial wound healing after treatment with 0.3 per cent and 0.15 per cent HA/high-K artificial tears was not significantly different compared to that after treatment with PBS. CONCLUSION: Hyaluronic acid and high potassium ion concentration artificial tears promoted corneal epithelial wound healing in the mechanical scraping model; however, in the alkali burn model, no significant beneficial effect of this treatment was observed.