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Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6) is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effec...
Context in source publication
Context 1
... LASIK and PRK methods were performed by a Wavelight Allegretto (400 Hz) excimer laser. In the PRK method the energy of excimer laser is applied directly onto deepithelialized corneal stroma (Figure 1). In the LASIK method the energy of excimer laser is applied on deeper lay- ers of stroma, i.e. at a larger distance from corneal epithe- lium (Figure 2). To create a flap we used a Moria micro- keratome during the LASIK method procedure, and when we applied the PRK method we removed corneal epithelium with an Amoils rotational brush. A procedure described in the study by Acera et al. 8 was applied to collect the samples of tears. The tear fluid was sampled from lower lateral tear meniscus with minimal irri- tation of ocular surface and the edge of eyelids, with no use of anesthetics (Figure 3). Each tear sample was taken by us- ing a cellulose microsurgical sponge (Alcon, USA). After sampling, the tear fluid was separated by centrifugation of the sponge in a 0.5 mL volume of phosphate buffered saline (PBS). The samples were centrifugated at 13,000 rpm for 15 min at 4°C (MPW-350 r, Med. Instruments, Poland). Col- lected samples were kept at -80°C until the final examina- ...
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Citations
... 25 Interleukin-6 has been extensively studied within the context of corneal wound healing and its expression is upregulated following corneal injury in human patients, as well as in animal and in vitro models. [26][27][28][29][30] Indirect suppression of IL-6 has been shown to have a negative effect on in vivo corneal epithelial cell migration in mice 29 and on in vitro immortalized human corneal epithelial cell migration. 29,30 Conversely, increases in IL-6 expression expedited corneal wound closure in scratch assays employing human 26,31 and rabbit corneal epithelial cells 32 and in in vivo rabbit corneal wound healing models. ...
... 44 Following injury, IL-6 is upregulated in human corneas, as well as in animal and in vitro models. [26][27][28][29] The increase in IL-6 expression facilitates and expedites epithelial wound closure. 26,31,33,45 In addition, IL-6 reduces the production of matrix metalloproteinase-2, which may have deleterious effects on wounded corneas. ...
... 29 The results of our study demonstrate increased IL-6 expression in injured corneas, in agreement with others. Peak IL-6 expression has been reported at one day or 24 h after corneal surgery in human patients, 27 and 7 days after corneal alkaline burn in mice and rabbits. 28,44 The peak IL-6 expression in our study was noted 24 h after corneal wounding, similar to the finding of Resan et al. 27 However, since in our study the first time point for IL-6 expression was 24 h post injury, and we cannot rule out an earlier peak of IL-6 expression. ...
Purpose
To establish a physiologically relevant ex vivo model of equine corneal epithelial wound healing.
Methods
Fourteen equine corneas were randomly assigned to one of two groups: wounded (n = 8) or unwounded (n = 6) controls. In the wounded group, the axial corneal epithelium was removed by applying a 6 mm filter paper disk soaked in 1N-NaOH for 60 s. Corneas were subsequently cultured using an air-liquid interface model. Evaluation of corneal healing was performed daily, and culture medium was collected. Corneas were randomly assigned to undergo processing via histopathology and RNAscope in situ hybridization for interleukin-6 (IL-6) and alpha-smooth muscle actin (αSMA) expression at T24, T48, and T72 h after wounding. Media of the cultured corneas were evaluated for the presence of lactate dehydrogenase (LDH) by a colorimetric assay.
Results
The ulcerated area of the wounded corneas decreased over time and all corneas healed within 72 h. Histologically, normal corneal architecture was observed including healthy epithelium (in areas other than the ulcerated ones), minimal stromal edema, intact endothelium, and Descemet's membrane. IL-6 expression was increased in wounded corneas compared with unwounded controls. LDH expression was elevated for both wounded and unwounded corneas at T24 but decreased substantially and was not detected at T48 in media from wounded and unwounded corneas, respectively. No αSMA expression was detected from either wounded or unwounded corneas.
Conclusions
The equine air-liquid interface, ex vivo, corneal epithelial wound healing model is effective and physiologically relevant. This model can be used in future studies evaluating various corneal therapies.
This chapter aims to cover the following aspects regarding complications following cross-linking (CXL): basic pathophysiology, risk factors, impact on the refractive status of the eye, and visual quality, prevention, and management. For didactic purposes, the complications were grouped into two types: early- or late onset. Early-onset complications included pain, infections, inflammation, and endothelial complications, whereas late-onset complications included contrast, visual loss, and biomechanical failure. This updated chapter focused particularly on the recent evidence concerning keratoconus progression, in spite of cross-linking (CXL failure), and undesirable topographic/refractive changes which incur in visual quality degradation (excessive flattening). The individual differences between the incidence and risk factors of these complications among different CXL technique strategies (epithelium-on, epithelium-off, accelerated CXL, fast CXL) are also discussed.KeywordsKeratoconusCross-linkingComplicationsHazeMeltingBiomechanical failureFlatteningKeratitisEpithelial defect
Neuropathic dry eye is one of the most frequently seen complications after corneal refractive surgery, however, its incidence decreases in a significant manner along the first six months postoperative, reaching between 10 and 45% incidence. However, little is known on the inflammatory status of the ocular surface during this recovery process. We aim to analyze the clinical and tear molecule concentration changes along six months after advanced surface ablation for myopia correction, in a prospective study including 18 eyes of 18 subjects who bilaterally underwent advanced surface ablation corneal refractive surgery. Clinical variables (uncorrected distance visual acuity, symptoms, conjunctival hyperemia, tear osmolarity, tear stability, corneal fluorescein staining, conjunctival lissamine staining, Schirmer test, and corneal esthesiometry) and a panel of 23 pro and anti-inflammatory cytokines/chemokines concentration in tears preoperatively and at 1, 3 and 6 months postoperatively were evaluated. We found that uncorrected distance visual acuity improved significantly from baseline at 1-month visit, symptoms improved and tear osmolarity decreased significantly from baseline at 3-month visit and there was a decrease in mechanical corneal threshold between 1-month and 3- and 6-month visits. Regarding tear molecules, IL-4, IL-5, IL-6, IL-13, IL-17A, and IFN-γ tear levels were significantly increased at all the three visits, compared to preoperative levels at V0; IL-2 and VEGF were also significantly increased at 1-month and 6-month visits, but not at 3-month visit, whereas IL-9 IL-10 and IL-12 were only significantly increased at 6-month visit. Although we found that there is a recovery in clinical variables at 6 months postoperatively (i.e. neuropathic dry eye was not developed in the sample), ocular surface homeostasis is not completely restored, as it can be seen by the changes in concentration of some pro and anti-inflammatory molecules measured in tears.
If tears are collected in a glass tube and observed with the naked eye, what we see is just an uncomplicated clear liquid. It is difficult to digest the level of complexity these drops offer. Even more unconceivable is how these few drops in the ocean of a body are affected by factors that are often in our control and seldom beyond. This chapter discusses how tear chemistry is affected by age, diet, surgery, medication etc.
This section covers interesting aspects of tear-based syndromes, artificial tears, those obtained from women in different stages of their lifecycle, babies and twins.Tear chemistry of contact lens users has been discussed in some detail.
