Early elastic and viscoelastic corneal biomechanical changes after photorefractive keratectomy and small incision lenticule extraction.

PURPOSE: To compare early changes in the corneal biomechanical parameters after photorefractive keratectomy (PRK) and small incision lenticule extraction (SMILE) and their correlations with corneal shape parameters. METHODS: One hundred twenty four eyes received myopic PRK and SMILE for similar amounts of myopia. Corneal tomography with Pentacam HR, biomechanical parameters using Corvis ST, and Ocular Response Analyzer (ORA) were evaluated before and 2 weeks after surgery. The change in each parameter was compared between groups, while the difference in central corneal thickness and cornea-compensated intraocular pressure measured before and after surgery were considered as covariates. RESULTS: A significant reduction was seen in the corneal stiffness parameter at first applanation, and an increase in deformation amplitude ratio (DAR), and integrated inverse radius (IIR) in both groups after surgery (p < 0.001) Changes in DAR, and IIR were significantly greater in the SMILE than in the PRK group (p < 0.001) Corneal hysteresis (CH) and corneal resistance factor (CRF) decreased in both SMILE and PRK groups after surgery, (p < 0.001) with no statistically significant difference between groups (p > 0.05) Among new Corvis ST parameters, DAR showed a significant correlation with changes in Ambrosio relational thickness in both groups (p < 0.05). CONCLUSIONS: Both techniques caused significant changes in corneal biomechanics in the early postoperative period, with greater elastic changes in the SMILE group compared to the PRK group, likely due to lower tension in the SMILE cap and thinner residual stromal bed in SMILE. There were no differences in viscoelastic changes between them, so the lower CH may reflect the volume of tissue removed.

[Study of the growth temperature of ocular surface microorganisms in norm and in infectious keratitis]. / Izuchenie temperaturnykh uslovii rosta mikroorganizmov glaznoi poverkhnosti v norme i pri infektsionnykh keratitakh.

Standard bacteriological examinations, which involve culturing microorganisms at 37 °C, are commonly used in clinical practice for diagnosing infectious diseases. However, the growth temperature of microorganisms on the ocular surface (OS) during infectious keratitis (IK) may not coincide with the laboratory standard, which is due to the characteristic features of heat exchange in the eye. PURPOSE: This exploratory study examines the distribution and properties of OS microorganisms isolated under different temperature cultivation conditions in patients with IK and healthy volunteers without ophthalmic pathology. MATERIAL AND METHODS: Fifteen participants were divided into two groups. Group 1 (n=10) consisted of patients with signs of unilateral infectious keratitis, while group 2 (n=5) served as the control group. A novel microbiological method was employed to isolate pure cultures of microorganisms. This method involved cultivating microorganisms at two temperature regimes (37 °C and 24 °C) and subsequently identifying them using biochemical, immunological, and physicochemical techniques, including mass spectrometry. Scanning electron microscopy (SEM) with lanthanide staining used as the reference method. The temperature status of the ocular surface was assessed using non-contact infrared thermography. RESULTS: The study demonstrated the presence of psychrotolerant microorganisms on the ocular surface, which exhibited growth at a relatively low temperature of 24 °C. These psychrotolerant microorganisms were found to be isolated from the ocular surface displaying signs of temperature dysregulation. Among such microorganisms are Acinetobacter lwoffii, Achromobacter xylosoxidans, Bacillus licheniformis, Enterococcus faecalis, Klebsiella oxytoca, Klebsiella pneumoniae, Micrococcus luteus, Pseudomonas luteola, Streptococcus spp. CONCLUSION: When identifying the causative agent of infectious keratitis, it is crucial to consider the divergence of growth temperature of ocular surface microorganisms. The presence of psychrotolerant microorganisms on the ocular surface, which can effectively grow at room temperature, should be taken into account, especially in cases of temperature dysregulation.

[Changes in the precorneal tear film at various stages of keratoconus]. / Izmenenie prekorneal'noi sleznoi plenki pri razlichnykh stadiyakh keratokonusa.

The combination of keratoconus (KC) with signs of dry eye disease (DES) has been described in numerous scientific publications. At the same time, there is a relationship between KC stage and an increase in the severity of DES symptoms, however, there is still no common understanding of the severity of xerotic process depending on the clinical course of keratectasia. PURPOSE: This study assesses the changes in the state of the precorneal tear film in KC relative to the stages of the disease. MATERIAL AND METHODS: The study included 50 patients (100 eyes) with bilateral non-operated KC from subclinical to stage IV. The following methods were used for a comprehensive assessment of the condition of the tear film: biomicroscopy of the anterior segment of the eye using vital dyes, functional tests (Norn, Schirmer, Jones tests), tearscopy of the lipid layer of the tear film with software processing of the results, OCT-meniscometry, as well as filling out the OSDI questionnaire by patients. RESULTS: The following significant changes were revealed as the KC stage progressed: an increase in the area of staining of the ocular surface with vital dyes, a decrease in the results of the Norn functional test and OCT-meniscometry, an increase in the areas of smaller thickness of lipids and areas of their complete absence according to tearscopy, as well as an increase in scores of the OSDI questionnaire. CONCLUSION: A comprehensive assessment of the condition of the tear film in KC indicates the relationship and the strengthening of the signs of DES as keratectasia progresses, and can be considered as justification for the need to prescribe tear replacement and reparative therapy that improves the condition of the ocular surface and stabilizes the precorneal tear film.

Development of graphitic carbon nitride quantum dots-based oxygen self-sufficient platforms for enhanced corneal crosslinking.

Keratoconus, a disorder characterized by corneal thinning and weakening, results in vision loss. Corneal crosslinking (CXL) can halt the progression of keratoconus. The development of accelerated corneal crosslinking (A-CXL) protocols to shorten the treatment time has been hampered by the rapid depletion of stromal oxygen when higher UVA intensities are used, resulting in a reduced cross-linking effect. It is therefore imperative to develop better methods to increase the oxygen concentration within the corneal stroma during the A-CXL process. Photocatalytic oxygen-generating nanomaterials are promising candidates to solve the hypoxia problem during A-CXL. Biocompatible graphitic carbon nitride (g-C3N4) quantum dots (QDs)-based oxygen self-sufficient platforms including g-C3N4 QDs and riboflavin/g-C3N4 QDs composites (RF@g-C3N4 QDs) have been developed in this study. Both display excellent photocatalytic oxygen generation ability, high reactive oxygen species (ROS) yield, and excellent biosafety. More importantly, the A-CXL effect of the g-C3N4 QDs or RF@g-C3N4 QDs composite on male New Zealand white rabbits is better than that of the riboflavin 5'-phosphate sodium (RF) A-CXL protocol under the same conditions, indicating excellent strengthening of the cornea after A-CXL treatments. These lead us to suggest the potential application of g-C3N4 QDs in A-CXL for corneal ectasias and other corneal diseases.

Accuracy of a novel method for IOP measurement without applying pressure on the cornea.

PURPOSE: To assess the accuracy of a prototype novel instrument for intra ocular pressure (IOP) measurements not involving corneal pressure application. DESIGN: Prospective case control study. METHODS: An institutional study including 16 healthy volunteers without ocular pathology. IOP in both eyes of the participants was measured four times in different body positions with the novel prototype and reference instrument (Goldmann applanation tonometer (GAT) or iCare (iCare Finland OY, Vantaa, Finland)). IOP results were compared between the prototype and the reference instruments in 116 pairs of measurement. RESULTS: Overall no statistically significant difference was found between the presented prototype and the reference instrument. Stratifying measurements by instrument used revealed no significant difference for GAT and statistical significant (yet clinically insignificant) difference for iCare. CONCLUSIONS: The presented prototype demonstrates good clinical agreement of IOP measuring results with reference instruments Further large-scale studies assessing this instrument in glaucoma patients are warranted.

Visual restoration with KPro after face allotransplantation with a grade III phthisical eye.

The Boston Keratoprosthesis type I (KPro-I) has been shown to be successful in restoring vision after severe ocular burns; however, its long-term outcomes in phthisical eyes have rarely been reported. A monocular woman with a history of severe alkali chemical injury necessitating facial transplantation presented with a light perception left eye after a complicated course, including failed KPro-I, therapeutic penetrating keratoplasty, endophthalmitis, hypotony, total retinal detachment, and structural changes, including a shrunken 18 mm axial length and eye wall thickening. The patient underwent a combined vitrectomy with silicone oil and KPro-I implantation, resulting in her regaining ambulatory visual acuity (20/250) at 3 years' follow-up.

Physiological Effects of Soat1 Inactivation on Homeostasis of the Mouse Ocular Surface.

Purpose: Soat1/SOAT1 have been previously reported to be critical for the biosynthesis of cholesteryl esters (CEs) in the mouse Meibomian glands (MGs) as the loss of function led to an arrest of CE production and a substantial accumulation of nonesterified cholesterol in the meibum, causing an increase in its melting temperature. The purpose of this study was to further investigate the role of Soat1 in meibogenesis and ocular surface physiology. Methods: The mouse ocular features of knockout Soat1-/- and wild type (WT) mice were studied using various ophthalmic and histological techniques, mouse lipidomes were monitored using liquid chromatography/mass spectrometry, whereas their transcriptomes were compared to characterize the effects of the mutation on the gene expression profiles in the MG and cornea. Results: Soat1-/- mice displayed increased tear production and severe corneal abnormalities, such as corneal thinning, (neo)vascularization, ulceration, and opacification that progressed with aging. Transcriptomic analyses led to identification of a range of significantly disrupted pathways, which included general and specific lipid metabolism-related pathways, keratinization, angiogenesis/(neo)vascularization, muscle contraction, and several other pathways. In addition, histological and histochemical experiments revealed morphological changes in the MG, cornea, and conjunctiva in Soat1-/- mice. Notably, the mRNA microarray expression level of Soat1 in WT MGs (log2 17.5) was 1000 × of that in the mouse cornea (log2 7.5). Conclusions: These findings suggest a direct involvement of Soat1/SOAT1 in MGs in maintaining ocular surface homeostasis, in general, and corneal health, specifically.

The Role of LC3-Associated Phagocytosis Inhibits the Inflammatory Response in Aspergillus fumigatus Keratitis.

Purpose: The purpose of this study was to investigate the role and mechanism of microtubule-associated protein light chain-3 (LC3)-associated phagocytosis (LAP) in the immune response to Aspergillus fumigatus (A. fumigatus) keratitis. Methods: The formation of single-membrane phagosomes was visualized in the corneas of healthy or A. fumigatus-infected humans and C57BL/6 mice using transmission electron microscopy (TEM). Rubicon siRNA (si-Rubicon) was used to block Rubicon expression. RAW 264.7 cells or mice corneas were infected with A. fumigatus with or without pretreatment of si-Rubicon and scrambled siRNA. RAW 264.7 cells were pretreated with Dectin-1 antibody or Dectin-1 overexpressed plasmid and then stimulated with A. fumigatus. Flow cytometry was used to label macrophages in normal and infected corneas of mice. In mice with A. fumigatus keratitis, the severity of the disease was assessed using clinical scores. We used lentiviral technology to transfer GV348-Ubi-GFP-LC3-II-SV40-Puro Lentivirus into the mouse cornea. The GFP-LC3 fusion protein was visualized in corneal slices using a fluorescence microscope. We detected the mRNA and protein expressions of the inflammatory factors IL-6, IL-1ß, and IL-10 using real-time PCR (RT-PCR) and ELISA. We detected the expression of LAP-related proteins Rubicon, ATG-7, Beclin-1, and LC3-II using Western blot or immunofluorescence. Results: Accumulation of single-membrane phagosomes within macrophages was observed in the corneas of patients and mice with A. fumigatus keratitis using TEM. Flow cytometry (FCM) analysis results show that the number of macrophages in the cornea of mice significantly increases after infection with A. fumigatus. LAP-related proteins were significantly elevated in the corneas of mice and RAW 264.7 cells after infection with A. fumigatus. The si-Rubicon treatment elevated the clinical score of mice. In A. fumigatus keratitis mice, the si-Rubicon treated group showed significantly higher expression of IL-6 and IL-1ß and lower expression of IL-10 and LC3-II compared to the control group. In RAW 264.7 cells, treatment with the Dectin-1 overexpressed plasmid upregulated the expression of LAP-related proteins, a process that was significantly inhibited by the Dectin-1 antibody. Conclusions: LAP participates in the anti-inflammatory immune process of fungal keratitis (FK) and exerts an anti-inflammatory effect. LAP is regulated through the Dectin-1 signaling pathway in A. fumigatus keratitis.

Analysis of the performance of the CorneAI for iOS in the classification of corneal diseases and cataracts based on journal photographs.

CorneAI for iOS is an artificial intelligence (AI) application to classify the condition of the cornea and cataract into nine categories: normal, infectious keratitis, non-infection keratitis, scar, tumor, deposit, acute primary angle closure, lens opacity, and bullous keratopathy. We evaluated its performance to classify multiple conditions of the cornea and cataract of various races in images published in the Cornea journal. The positive predictive value (PPV) of the top classification with the highest predictive score was 0.75, and the PPV for the top three classifications exceeded 0.80. For individual diseases, the highest PPVs were 0.91, 0.73, 0.42, 0.72, 0.77, and 0.55 for infectious keratitis, normal, non-infection keratitis, scar, tumor, and deposit, respectively. CorneAI for iOS achieved an area under the receiver operating characteristic curve of 0.78 (95% confidence interval [CI] 0.5-1.0) for normal, 0.76 (95% CI 0.67-0.85) for infectious keratitis, 0.81 (95% CI 0.64-0.97) for non-infection keratitis, 0.55 (95% CI 0.41-0.69) for scar, 0.62 (95% CI 0.27-0.97) for tumor, and 0.71 (95% CI 0.53-0.89) for deposit. CorneAI performed well in classifying various conditions of the cornea and cataract when used to diagnose journal images, including those with variable imaging conditions, ethnicities, and rare cases.

Comparison of the repeatability and reproducibility of corneal thickness mapping using optical coherence tomography according to tear film break-up time.

BACKGROUND: To compare the repeatability and reproducibility of corneal and corneal epithelial thickness mapping using anterior segment optical coherence tomography (AS-OCT) according to tear film break-up time (TBUT). METHODS: The included eyes were divided into three subgroups according to TBUT (group 1: TBUT ≤ 5 s, group 2: 5 s < TBUT ≤ 10 s, and group 3: TBUT > 10 s). All eyes were imaged separately thrice by two operators to obtain the thickness maps (TMs) of the cornea and corneal epithelium based on spatial zones encompassing a 9-mm-diameter area. Each TM consisted of 25 areas. Intraoperator (repeatability) and interoperator (reproducibility) standard deviations (Sws), coefficients of variation (CoVs), and intraclass correlation coefficients (ICCs) among the tests were calculated and compared in all the areas. RESULTS: Altogether, 132 eyes of 67 subjects were included (50, 47, and 35 eyes in groups 1, 2, and 3; respectively). The ICCs of corneal epithelial thickness and corneal thickness were > 0.75 in most of the areas. Pairwise comparisons showed that AS-OCT exhibited lower repeatability in group 1 than in groups 2 and 3 (P < 0.05). However groups 2 and 3 showed similar results. Sws and CoVs of corneal epithelial thickness exhibited no significant interoperator differences. While no significant differences were observed in corneal thickness in most of the areas. CONCLUSIONS: TBUT significantly influences the repeatability of corneal and corneal epithelial thickness measurements. Poor tear film stability requires careful evaluation of corneal epithelial thickness.

Case report: Nerve fiber regeneration in children with melanocortin 4 receptor gene mutation related obesity treated with semaglutide.

Melanocortin 4 receptor (MC4R) mutations are the commonest cause of monogenic obesity through dysregulation of neuronal pathways in the hypothalamus and prefrontal cortex that regulate hunger and satiety. MC4R also regulates neuropathic pain pathways via JNK signaling after nerve injury. We show evidence of corneal small fiber degeneration in 2 siblings carrying a heterozygous missense variant c.508A>G, p.Ille170Val in the MC4R gene. Both children were treated with once weekly semaglutide for 6 months with no change in weight, and only a minor improvement in HbA1c and lipid profile. However, there was evidence of nerve regeneration with an increase in corneal nerve fiber density (CNFD) [child A (13.9%), child B (14.7%)], corneal nerve branch density (CNBD) [child A (110.2%), child B (58.7%)] and corneal nerve fiber length (CNFL) [child A (21.5%), child B (44.0%)].

Clinical History Method versus Corneal Tomographers in Estimating Corneal Power after Photorefractive Surgery

AIMS: To investigate the concordance between the corneal power determined by various approaches with two tomographers (MS-39® and Galilei G6®) and the clinical history method (CHM) in patients undergoing photorefractive surgery with excimer laser for myopic errors. MATERIAL AND METHODS: Prospective cohort study. Patients undergoing keratorefractive surgery, and having pre- and postoperative keratometries, and tomographies, were included. RESULTS: In 90 eyes, the differences in the power estimated by the CHM and the one determined by four approaches with the corneal tomographers, which included measurements of the posterior cornea, did not show statistically significant differences in their averages. However, the 95% limits of agreement were very wide. After obtaining regression formulas to adjust the values of these four variables, the results of the agreement analysis were similar. CONCLUSION: Although certain values either directly determined or derived from measurements with the Galilei® and MS-39®corneal tomographers, approximated the estimated value of postoperative corneal power according to the CHM, due to the amplitude of their limits of agreement, these calculations must be taken with care, because they may not be accurate in a given eye.

Evaluation of anterior segment parameters between pregnancy trimesters and postpartum with pentacam scheimflug imaging: a prospective study.

PURPOSE: To evaluate the effect of pregnancy on the anterior chamber, corneal parameter, and intraocular pressure measurements; and compare the results between trimesters, postpartum and non-pregnant healthy age-matched women. METHODS: This prospective study included 41 pregnant women and 53 non-pregnant women. Four measurements were taken from the pregnant women, in each trimester and postpartum third month, and once from the control group. Of the individuals included in the study, anterior chamber depth (ACD), anterior chamber volume (ACV), K1 (flat keratometry), K2 (steep keratometry), Kmean (mean value of K1 and K2), anterior chamber angle (ACA), central corneal thickness (CCT), thinnest corneal thickness (TCT), astigmatism value (AST), corneal volume (CV), biometry, axial length (AL), spherical equivalent (SFEQ), intraocular lens power (ILP), VA (visual acuity) datas were recorded. RESULTS: We observed a statistically significant decrease in K2, CCT, ACD, AL and CV in the postpartum period (p = 0.025, p < 0.001, p = 0.029, p = 0.005, p = 0.004 respectively) and a statistically significant increase in ACV, CCT, and TCT as the gestational week progressed in the pregnant group (p = 0.007, p < 0.001, p = 0.025, respectively). A statistically significant decrease in IOP towards to the third trimester, and an increase in the postpartum period was observed (p < 0.001). We did not observe statistically significant changes in K1, Kmean, AST, ACA, VA, ILP, and SFEQ values. CONCLUSION: It is important to investigate the physiological changes that may occur during pregnancy, distinguish them from pathological changes, and avoid unnecessary treatment. We consider that it's also important to guide the timing of anterior segment surgeries such as cataract and refractive surgery and to prescribe glasses/contact lenses.

Identification of Keratoconus-Related Phenotypes in Three Ppip5k2 Mouse Models.

Purpose: It is necessary to establish a mouse model of keratoconus (KC) for research and therapy. We aimed to determine corneal phenotypes in 3 Ppip5k2 mouse models. Methods: Central corneal thickness (CCT) was determined using spectral domain optical coherence tomography (SD-OCT) in Ppip5k2+/K^ (n = 41 eyes), Ppip5k2K^/K^ (n = 17 eyes) and 2 knock-in mice, Ppip5k2S419A/+ (n = 54 eyes) and Ppip5k2S419A/S419A (n = 18 eyes), and Ppip5k2D843S/+ (n = 42 eyes) and Ppip5k2D843S/D843S (n = 44 eyes) at 3 and 6 months. Pachymetry maps were generated using the Mouse Corneal Analysis Program (MCAP) to process OCT images. Slit lamp biomicroscopy was used to determine any corneal abnormalities, and, last, hematoxylin and eosin (H&E) staining using corneal sections from these animals was used to examine morphological changes. Results: CCT significantly decreased from 3 to 6 months in the Ppip5k2+/K^ and Ppip5k2K^/K^ mice compared to their littermate controls. OCT-based pachymetry maps revealed abnormally localized thinning in all three models compared to their wild-type (WT) controls. Slit lamp examinations revealed corneal abnormalities in the form of bullous keratopathy, stromal edema, stromal scarring, deep corneal neovascularization, and opacities in the heterozygous/homozygous mice of the three models in comparison with their controls. Corneal histological abnormalities, such as epithelial thickening and stromal layer damage, were observed in the heterozygous/homozygous mice of the three models in comparison with the WT controls. Conclusions: We have identified phenotypic and histological changes in the corneas of three mouse lines that could be relevant in the development of animal models of KC.

Efficacy and Safety of the Modified Cretan Protocol in Patients with Post-LASIK Ectasia

Objectives: To investigate the clinical efficacy and safety of the modified Cretan protocol in patients with post-laser in situ keratomileusis ectasia (PLE). Materials and Methods: In this retrospective study, 26 eyes of 16 patients with PLE were treated with the modified Cretan protocol (combined transepithelial phototherapeutic keratectomy and accelerated corneal collagen cross-linking). Visual, refractive, tomographic, and aberrometric outcomes and point spread function (PSF) were recorded preoperatively and at 6, 12, and 24 months after treatment. Results: Both uncorrected and best corrected visual acuity were stable at 24 months postoperatively compared to baseline (from 0.89±0.36 to 0.79±0.33 logarithm of the minimum angle of resolution [LogMAR] and 0.31±0.25 to 0.24±0.19 LogMAR, respectively, p>0.05 for all values). The mean K1, K2, Kmean, thinnest corneal thickness, and spherical aberration at baseline were 45.76±5.75 diopters (D), 48.62±6.17 D, 47.13±5.89 D, 433.16±56.86 µm, and -0.21±0.63 µm respectively. These values were reduced to 42.86±6.34 D, 45.92±6.74 D, 44.21±6.4 D, 391.07±54.76 µm, and -0.51±0.58 µm at 24 months postoperatively (p<0.001, p=0.002, p<0.001, p=0.001, and p=0.02, respectively). The mean spherical equivalent, manifest cylinder, Kmax, central corneal thickness, other corneal aberrations (root mean square, trefoil, coma, quatrefoil, astigmatism), and PSF remained stable (p>0.05 for all variables), while anterior and posterior elevation were significantly improved at 24 months postoperatively (p<0.001 and p=0.02, respectively). No surgical complications occurred during the 24-month follow-up. Conclusion: The modified Cretan protocol is a safe and effective treatment option for PLE patients that provides visual stabilization and significant improvement in topographic parameters during the 24-month follow-up. Further studies are needed to support our results.

Corneal innervation changes in Alzheimer's: implications for sensory dysfunction.

PURPOSE: To compare, between Alzheimer's disease (AD) patients and healthy individuals, corneal subbasal nerve plexus (CSNP) parameters and corneal sensitivities. METHODS: Twenty-two patients who were followed up with Alzheimer's disease (Alzheimer's group) and 18 age- and gender-matched healthy individuals (control group) were included in this cross-sectional study. CSNP parameters, including nerve fiber length (NFL), nerve fiber density (NFD), and nerve branch density (NBD), were evaluated using in vivo confocal microscopy. Corneal sensitivity was evaluated using a Cochet-Bonnet esthesiometer. The results were compared between the two groups. RESULTS: In the Alzheimer's group, NFL was 12.2 (2.4) mm/mm2, NFD was 12.5 [3.1] fibers/mm2, and NBD was 29.7 [9.37] branches/mm2. In the control group, NFL was 16.5 (2.0) mm/mm2, NFD was 25.0 [3.13] fibers/mm2, and NBD was 37.5 [10.9] branches/mm2. All three parameters were significantly lower in the Alzheimer's group compared to the control group (p < 0.001, p < 0.001, and p = 0.001, respectively). Similarly, corneal sensitivity was significantly lower in the Alzheimer's group (55.0 [5.0] mm) compared to the control group (60.0 [5.0] mm) (p < 0.001). CONCLUSION: We determined that, in AD, corneal sensitivity decreases significantly, in parallel with the decrease in corneal nerves. Changes in the corneal nerve plexus and a decrease in corneal sensitivity may be used in the early diagnosis and follow-up of AD. In addition, ocular surface problems secondary to these changes should also be kept in mind.

Development of an injectable oxidized dextran/gelatin hydrogel capable of promoting the healing of alkali burn-associated corneal wounds.

The cornea serves as an essential shield that protects the underlying eye from external conditions, yet it remains highly vulnerable to injuries that could lead to blindness and scarring if not promptly and effectively treated. Excessive inflammatory response constitute the primary cause of pathological corneal injury. This study aimed to develop effective approaches for enabling the functional repair of corneal injuries by combining nanoparticles loaded with anti-inflammatory agents and an injectable oxidized dextran/gelatin/borax hydrogel. The injectability and self-healing properties of developed hydrogels based on borate ester bonds and dynamic Schiff base bonds were excellent, improving the retention of administered drugs on the ocular surface. In vitro cellular assays and in vivo animal studies collectively substantiated the proficiency of probucol nanoparticle-loaded hydrogels to readily suppress proinflammatory marker expression and to induce the upregulation of anti-inflammatory mediators, thereby supporting rapid repair of rat corneal tissue following alkali burn-induced injury. As such, probucol nanoparticle-loaded hydrogels represent a prospective avenue to developing long-acting and efficacious therapies for ophthalmic diseases.

Functionalized chitosan based antibacterial hydrogel sealant for simultaneous infection eradication and tissue closure in ocular injuries.

Management of infections at ocular injury often requires prolonged and high dose of antibiotic, which is associated with challenges of antibiotic resistance and bacterial biofilm formation. Tissue glues are commonly used for repairing ocular tissue defects and tissue regeneration, but they are ineffective in curing infection. There is a critical need for antibacterial ocular bio-adhesives capable of both curing infection and aiding wound closure. Herein, we present the development of an imine crosslinked N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC)­silver chloride nanocomposites (QAm1-Agx) and poly-dextran aldehyde (PDA) based bactericidal sealant (BacSeal). BacSeal exhibited potent bactericidal activity against a broad spectrum of bacteria including their planktonic and stationary phase within a short duration of 4 h. BacSeal effectively reduced biofilm-embedded MRSA and Pseudomonas aeruginosa by ∼99.99 %. In ex-vivo human cornea infection model, BacSeal displayed ∼99 % reduction of ocular infection. Furthermore, the hydrogel exhibited excellent sealing properties by maintaining ocular pressure up to 75 mm-Hg when applied to human corneal trauma. Cytotoxicity assessment and hydrogel-treated human cornea with a retained tissue structure, indicate its non-toxic nature. Collectively, BacSeal represents a promising candidate for the development of an ocular sealant that can effectively mitigate infections and may assist in tissue regeneration by sealing ocular wounds.

Analysis of surgically induced astigmatism of the anterior, posterior, and total cornea after implantable collamer lens implantation: a comparative study between temporal and superior clear corneal incisions.

BACKGROUND: To comparatively analyze the surgically induced astigmatism (SIA) of the anterior, posterior, and total corneas of eyes undertaking implantable collamer lens (ICL) implantation with temporal or superior corneal incisions. METHODS: One hundred and nine eyes of 109 patients who received ICL implantation were recruited: 40 eyes had temporal incisions and 69 eyes had superior incisions. Total corneal refractive power (TCRP); simulated keratometry of the anterior (Sim-KAnt) and posterior (Sim-KPost) corneal curvature; and astigmatism of the anterior (CAAnt), posterior (CAPost), and total (CATCRP) cornea were recorded through a Pentacam preoperatively and 3 months postoperatively. The SIA of the anterior, posterior, and total cornea were also compared between the two groups. RESULTS: There were no significant intergroup differences for TCRP, Sim-KAnt, Sim-KPost, CAAnt, CAPost, or CATCRP, preoperatively. However, values of CAAnt, CAPost, and CATCRP with temporal incision were significantly higher than those parameters with superior incision postoperatively. All of the SIA of the anterior, posterior, and total cornea were significantly lower for temporal incision than those with a superior incision (p < 0.001, p = 0.006 and p = 0.001 respectively). Meanwhile, the superior incisions created against-the-rule (ATR) astigmatism, and temporal incisions always induce with-the-rule (WTR) astigmatism in total cornea. CONCLUSIONS: A superior incision may be suitable for correcting WTR astigmatism, while a temporal incision for correcting ATR astigmatism when using a non-toric ICL. Meanwhile, temporal incision could be a better choice with little preoperative astigmatism or that preoperative astigmatism would be corrected with toric ICLs. TRIAL REGISTRATION: Registration number: ChiCTR2100051739. Prospectively registered: 01 October 2021.

Associations Between Visual Functions and Severity Gradings, Corneal Scatter, or Higher-Order Aberrations in Fuchs Endothelial Corneal Dystrophy.

Purpose: The purpose of this study was to investigate the associations between visual function and severity grading, corneal scatter, or higher-order aberrations (HOAs) in patients with Fuchs endothelial corneal dystrophy (FECD). Methods: This observational case series study included 49 eyes of 27 patients with FECD and 10 eyes of 10 healthy individuals. We evaluated corrected distance visual acuity (CDVA) using Landolt-C and Early Treatment Diabetic Retinopathy Study charts and contrast sensitivity using the CSV-1000E chart and CSV-1000RN letter chart. We analyzed the associations between visual function and explanatory variables, including age, modified Krachmer grade, central corneal thickness (CCT), anterior segment optical coherence tomography (AS-OCT)-based grade, HOAs, intraocular straylight, and corneal densitometry. We additionally conducted receiver operating characteristic (ROC) analysis to identify the corneal densitometry thresholds for decreased visual function. Results: There were significant associations between visual function and the modified Krachmer grade, CCT, AS-OCT-based grade, HOAs, intraocular straylight, and corneal densitometry. A modified Krachmer grade ≥ 3 was identified as a threshold for decreased visual function. Multivariate analysis showed that corneal densitometry was significantly associated with all visual function parameters, and HOAs were significantly associated with CDVA but not with contrast sensitivity. ROC analysis revealed that corneal densitometry of the posterior layer at 0 to 2 mm ≥ 10 grayscale units (GSU), was identified as a threshold for decreased visual function. Conclusions: HOAs, forward and backward light scatter affected visual function, with backward light scatter being the most influential. In patients with FECD, modified Krachmer grade ≥ 3 and corneal densitometry ≥ 10 GSU were thresholds for visual disturbance.