Corneal Hydration Research Articles

A hybrid genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier ocular drug delivery platform

The objective of this study was to develop a novel hybrid genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier (NLC) drug delivery platform. An ophthalmic anti-inflammatory drug, baicalin (BN) was chosen as the model drug. BNNLC was prepared using melt-emulsification combined with ultra-sonication technique. Additionally, a dual pH- and thermo-sensitive hydrogel composed of carboxymethyl chitosan (CMCS) and poloxamer 407 (F127) was fabricated by a cross-linking reaction with a nontoxic crosslinker genipin (GP). GP-CMCS/F127 hydrogel was characterized by FTIR, NMR, XRD and SEM. The swelling studies showed GP-CMCS/F127 hydrogel was both pH- and thermo-sensitive. The results of in vitro release suggested BNNLC gel can prolong the release of baicalin comparing with BN eye drops and BNNLC. Ex vivo cornea permeation study was evaluated using Franz diffusion cells. The apparent permeability coefficient (Papp) of BNNLC gel was much higher (4.46-fold) than that of BN eye drops. Through the determination of corneal hydration levels, BNNLC gel was confirmed that had no significant irritation to cornea. Ex vivo precorneal retention experiments were carried out by a flow-through approach. The results indicated that the NLC-based hydrogel can prolong precorneal residence time. In conclusion, the hybrid NLC-based hydrogel has a promising potential for application in ocular drug delivery.

The influence of hydration on different mechanical moduli of the cornea.

To determine the interrelation of different elastic moduli of the cornea and to investigate their dependency on corneal hydration. Rabbit eyes were divided into four groups. Corneas were excised and mounted into a Barron artificial anterior chamber. Various corneal hydration steady states were achieved with different dextran T-500 concentrations in the anterior chamber, as well as on the corneal anterior surface. The treatment-solutions of each group contained either 5, 10, 15, or 20% w/w dextran. Ultrasound pachymetry was used to measure central corneal thickness. Brillouin microscopy of the central cornea determined the longitudinal bulk modulus by means of Brillouin frequency shift. Subsequently, a 5-mm-wide central strip was taken for extensiometry to measure the tangential elastic modulus. The longitudinal bulk modulus was 1.2-times higher in corneas dehydrated with 20% dextran compared to those hydrated with 5% dextran. In contrast, the tangential elastic modulus increased by 4.4 times. The obtained longitudinal bulk moduli were two orders of magnitude bigger than the tangential elastic moduli. Regression analysis of longitudinal bulk modulus and tangential elastic modulus revealed a quadratic relation. The bulk modulus seemed to be independent of tension, whereas the elastic modulus was tension-dependent. Greater corneal hydration led to significantly thicker pachymetry. Corneal biomechanics are highly dependent on the level of corneal hydration. Surprisingly, tangential elastic moduli were more sensitive to hydration changes than longitudinal bulk moduli. A quadratic relation was found between both moduli.

Quantifying the effects of hydration on corneal stiffness with noncontact optical coherence elastography

To quantify the effects of the hydration state on the Young's modulus of the cornea. Biomedical Optics Laboratory, University of Houston, Houston, Texas, USA. Experimental study. Noncontact, dynamic optical coherence elastography (OCE) measurements were taken of insitu rabbit corneas in the whole eye-globe configuration (n=10) and at an artificially controlled intraocular pressure of 15mm Hg. Baseline OCE measurements were taken by topically hydrating the corneas with saline for 1hour. The corneas were then dehydrated topically with a 20% dextran solution for another hour, and the OCE measurements were repeated. A finite element method was used to quantify the Young's modulus of the corneas based on the OCE measurements. The thickness of the corneas shrank considerably after topical addition of the 20% dextran solution (∼680 μm to ∼370 μm), and the OCE-measured elastic-wave speed correspondingly decreased (∼3.2m/s to ∼2.6m/s). The finite element method results showed an increase in Young's modulus (500kPa to 800kPa) resulting from dehydration and subsequent thinning. Young's modulus increased significantly as the corneas dehydrated and thinned, showing that corneal geometry and hydration state are critical factors for accurately quantifying corneal biomechanical properties.

Therapeutic uses of scleral contact lenses for ocular surface disease: patient selection and special considerations.

Scleral lenses are being prescribed for the management of corneal irregularity, uncomplicated refractive error, and ocular surface disease. There are many potential therapeutic uses of scleral lenses in addition to providing similar benefits as corneal gas permeable lenses. Scleral contact lenses are a valuable therapeutic tool for patients with ocular surface disease as these lenses protect the ocular surface, provide continuous corneal hydration while providing optimal visual correction, and are often used in conjunction with other therapies.

FORMULATION AND EVALUATION OF TROPICAMIDE IN-SITU GELS LOADED SOLID LIPID NANOPARTICLES FOR OCULAR DRUG DELIVERY

The aim of present work Formulation and Evaluation of Tropicamide In-situ Gels loaded Solid Lipid Nanoparticles for Ocular Drug Delivery. The surface morphological of SLN was carried out by TEM. The Tropicamide loaded solid lipid nanoparticles was measured the average particle size was ranges from 182.1+3.12nm to 390.1±2.10 nm. The zeta potential ranges from -0.17±1.4 mV to -3.80±1.5 mV. The entrapment efficiency 66.2 % to 89.2 %. Drug content was ranges from 0.112mg/ml to 0.502 mg/ml. The percentage yield ranges from was ranges from 0.112mg/ml to 0.502 mg/ml. The polydispersity index ranged from 1.011±0.15 to 1.327±0.13. These SLN enriched in Chitosan gels the pH of the formulations range from 6.8 to 6.9. The gelling strength ranged from 129 sec to 152 sec. The bioadhesive force was ranges from 10.21 ±1.15 dynes/cm2 to 15.23 ± 1.22 dynes/cm2. The viscosity was ranges from 2212 ± 1.14 cps to 2420± 1.19 cps. The spreadability coefficient was ranges from 11.2 ± 1.10 gms/sec to 13.3 ± 1.21 gms/sec. The in-vitro diffusion release studies carried out at 12 hrs TSLNGF19 shows the 79.2 ± 0.32. The ex vivo permeation studies for optimized formulation the increased drug permeation and corneal accumulation. In vitro corneal permeation profile of tropicamide loaded SLN from the chitosan gels and commercial eye drop solution (Tropicacyl) across the isolated porcine cornea. The ocular tolerance studies performed with HETCAM assay, corneal hydration study, histopathological studies. The stability studies of chitosan gels for long-term stability as per ICH guidelines (25°C ± 2°C / 60% RH ± 5% RH) &accelerated stability as per ICH guidelines (40°C ± 2°C / 75% RH ± 5% RH) there is no changes in gelling strength, bioadhesive force, viscosity, spreadability coefficient in optimized formulation. Keywords: Chitosan, Corneal hydration studies, ex vivo permeation, in vitro diffusion studies, Solid Lipid Nanoparticles

Effects of Corneal Hydration on Brillouin Microscopy In Vivo.

PurposeTo investigate how corneal hydration affects the Brillouin frequency of corneal stroma.MethodsFrom a simple analytical model considering the volume fraction of water in corneal stroma, we derived the dependence of Brillouin frequency on hydration and hydration-induced corneal thickness variation. The Brillouin frequencies of fresh ex vivo porcine corneas were measured as their hydration was varied in dextran solution and water. Healthy volunteers (8 eyes) were scanned in vivo repeatedly over the course of 9 hours, and the diurnal variations of Brillouin frequency and central corneal thickness (CCT) were measured.ResultsThe measured dependence of Brillouin frequency on hydration, both ex vivo and in vivo, agreed well with the theoretical prediction. The Brillouin frequencies of human corneas scanned immediately after waking were on average ∼25 MHz lower than their daytime average values. For stabilized corneas, the typical variation of Brillouin frequency was ± 7.2 MHz. With respect to CCT increase or swelling, the Brillouin frequency decreased with a slope of −1.06 MHz/μm in vivo.ConclusionsThe ex vivo and in vivo data agree with our theoretical model and support that the effect of corneal hydration on Brillouin frequency comes predominantly from the dependence of the tissue compressibility on the water. Corneal hydration correlates negatively with the Brillouin frequency. During daytime activities, the influence of physiological hydration changes in human corneas is < ± 10 MHz. The sensitivity to hydration may potentially be useful in detecting abnormal hydration change in patients with endothelial disorders.

Relationship between initial corneal hydration and stiffening effects of corneal crosslinking treatment

To characterize the mechanical property improvement of riboflavin and ultraviolet light corneal crosslinking (CXL) procedure in artificially swollen human and porcine corneas. Computational Biomechanics Research Laboratory, Mechanical and Industrial Engineering Department, University of Illinois at Chicago, Illinois, USA. Experimental study. Porcine and human donor corneas were crosslinked atdifferent hydration levels using riboflavin-dextran solutions of different osmolality. Four porcine groups (Hw [hydration in mg H2O/mg dry tissue]=3.3±0.2 [SD]; 4.0±0.1; 5.1±0.1; 5.6±0.1) and 3 human groups (Hw=3.2±0.1; 3.9±0.2; 5.3±0.3) were considered. The mechanical properties were measured by uniaxial tensile experiments during which the hydration of samples was the same as the hydration at which they were crosslinked. Tensile properties of 2 porcine groups (Hw=5.1±0.1; 5.6±0.1) were also measured when their average hydration was lowered to 4.0mgH2O/mg dry tissue. The CXL procedure significantly increased tensile properties of both human and porcine samples in each hydration group (P<.05). The improvement in tensile properties was hydration-dependent, that is, samples crosslinked at higher hydration levels showed lower maximum tensile stress. The behavior of samples crosslinked at different initial hydration but tested mechanically at similar hydration showed insignificant difference (P=.7). Increasing the hydration of porcine and human corneal samples before the CXL treatment had insignificant influence on tensile property improvement, as measured by testing specimens at similar hydration.

Injection of Cultured Cells with a ROCK Inhibitor for Bullous Keratopathy

BackgroundCorneal endothelial cell (CEC) disorders, such as Fuchs’s endothelial corneal dystrophy, induce abnormal corneal hydration and result in corneal haziness and vision loss known as bullous keratopathy. We investigated whether injection of cultured human CECs supplemented with a rho-associated protein kinase (ROCK) inhibitor into the anterior chamber could increase CEC density.MethodsWe performed an uncontrolled, single-group study involving 11 persons who had received a diagnosis of bullous keratopathy and had no detectable CECs. Human CECs were cultured from a donor cornea; a total of 1×106 passaged cells were supplemented with a ROCK inhibitor (final volume, 300 μl) and injected into the anterior chamber of the eye that was selected for treatment. After the procedure, patients were placed in a prone position for 3 hours. The primary outcome was restoration of corneal transparency, with a CEC density of more than 500 cells per square millimeter at the central cornea at 24 weeks after cell injection. Secondary outcomes were a corneal thickness of less than 630 μm and an improvement in best corrected visual acuity equivalent to two lines or more on a Landolt C eye chart at 24 weeks after cell injection.ResultsAt 24 weeks after cell injection, we recorded a CEC density of more than 500 cells per square millimeter (range, 947 to 2833) in 11 of the 11 treated eyes (100%; 95% confidence interval [CI], 72 to 100), of which 10 had a CEC density exceeding 1000 cells per square millimeter. A corneal thickness of less than 630 μm (range, 489 to 640) was attained in 10 of the 11 treated eyes (91%; 95% CI, 59 to 100), and an improvement in best corrected visual acuity of two lines or more was recorded in 9 of the 11 treated eyes (82%; 95% CI, 48 to 98).ConclusionsInjection of human CECs supplemented with a ROCK inhibitor was followed by an increase in CEC density after 24 weeks in 11 persons with bullous keratopathy. (Funded by the Japan Agency for Medical Research and Development and others; UMIN number, UMIN000012534.)

Effect of UVA/Riboflavin Collagen Crosslinking on Biomechanics of Artificially Swollen Corneas.

The purpose of this study was to characterize the relation between corneal hydration and stiffening effects of the UVA/riboflavin collagen crosslinking treatment and to investigate how artificially swelling the cornea prior to this treatment procedure affects tensile property improvement. Porcine corneas were collagen crosslinked in vitro at different hydration levels using a number of hypoosmolar and isoosmolar riboflavin solutions. Thickness of the specimens prior to crosslinking was taken as a proxy for their hydration and was used to divide them into different thickness groups. A Dynamic Mechanical Analysis (DMA) machine was used to perform mechanical tensile tests. The hydration of specimens during the mechanical tests was kept similar to the hydration at which they were crosslinked. The recorded force was used to calculate the maximum tensile stress and tangent modulus as a function of thickness (hydration) prior to collagen crosslinking treatment. Collagen crosslinking with either a hypoosmolar or isoosmolar solution significantly increased corneal tensile modulus (P < 0.05). Corneas that were swollen prior to crosslinking showed significantly softer tensile properties compared with those that were crosslinked at lower hydration (P < 0.05). Although the degree of tensile property improvement was hydration dependent, the stiffness of samples crosslinked at higher hydration was not significantly different than the stiffness of those crosslinked at lower hydration when the hydration was kept similar in the mechanical experiments. Swelling porcine corneas to the different extents prior to collagen crosslinking treatment does not significantly change the amount of biomechanical improvement if tensile properties are measured at similar hydration.

An approach to revolutionize cataract treatment by enhancing drug probing through intraocular cell line

ABSTRACTThe purpose of this study is to prepare and characterize solid lipid nanoparticles (SLN) of N-Acetyl Carnosine (NAC) to treat cataract since surgery necessitates equipments and professional help. Cataract is believed to be formed by the biochemical approach where the crystalline eye proteins lose solubility and forms high molecular weight masses. Added advantages of SLN of NAC (henceforth referred as SLN-NAC) in the study are reduced size, sustained release and better corneal penetration of drug. The method of preparation of SLN-NAC by Mill’s method is unique in itself.The size of the SLN-NAC was 75 ± 10 nm in the range of ideal for penetration. The in-vitro release study and the SLN-NAC formulations prepared with Mill’s method demonstrated sustained release up to 24 h following an initial burst after 1 h. The zeta potential of the prepared formulation was −22.1 ± 1 mV. Corneal permeation studies using goat corneas indicate that SLN-NAC penetration rate was higher than those from NAC eye drops. Corneal hydration studies indicated that the formulation caused no harm to the corneal cells.Therefore it may be concluded that SLN-NAC may revolutionize cataract treatment and reversal by improving drug permeation, reducing toxicity and no damage to corneal tissue.

Central Corneal Thickness of Healthy Lowlanders at High Altitude: A Systematic Review and Meta-Analysis

ABSTRACTPurpose: Central corneal thickness, a marker of corneal hydration and metabolism, was reported to increase at high elevations. This study aimed to assess the effect of chronic high-altitude exposure on the central corneal thickness of healthy lowlanders with unoperated corneas, and determine if a relationship exists between exposure time and corneal edema formation.Materials and Methods: The PubMed, Embase, Scopus, Cochrane Library, and Airiti Library databases were searched up to 2017 January 31 for prospective cohort studies performed above 2500 m in healthy lowlanders with measurements of the central corneal thickness. Subjects with prior eye surgery, contact lens, and non-hypobaric hypoxic exposure were excluded.Results: Seven studies of 207 adults were included. The pooled effect of high-altitude exposure on the central corneal thickness for < 12 hours, 3–5 days, 6–7 days, and > 10 days was a mean difference of 13.4 (95% confidence interval: 5.1–21.6) μm with moderate heterogeneity (p < 0.05, I2 = 59%), 19.3 (95% confidence interval: 9.7–29) μm with low heterogeneity (p = 0.88, I2 = 0%), 20.4 (95% confidence interval: 10.3–30.5) μm with low heterogeneity (p = 0.73, I2 = 0%), and 30.8 (95% confidence interval: 20.4–41.2) μm with low heterogeneity (p = 0.69, I2 = 0%), respectively. Baseline differences between pre-exposure and post-exposure were not statistically significant. Regression analysis revealed a significant linear relation between high-altitude exposure time and corneal edema formation that exceeded 5% after 10 days.Conclusions: High-altitude exposure induces central corneal thickening with significant linear progression over time, whereas it takes over 10 days to reach clinical significance in healthy lowlanders with unoperated corneas, and changes in central corneal thickness are reversible after descent to lower elevations.

Activation of mitophagy leads to decline in Mfn2 and loss of mitochondrial mass in Fuchs endothelial corneal dystrophy

Human corneal endothelial cells (HCEnCs) are terminally differentiated cells that have limited regenerative potential. The large numbers of mitochondria in HCEnCs are critical for pump and barrier function required for corneal hydration and transparency. Fuchs Endothelial Corneal Dystrophy (FECD) is a highly prevalent late-onset oxidative stress disorder characterized by progressive loss of HCEnCs. We previously reported increased mitochondrial fragmentation and reduced ATP and mtDNA copy number in FECD. Herein, carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-induced mitochondrial depolarization decreased mitochondrial mass and Mfn2 levels, which were rescued with mitophagy blocker, bafilomycin, in FECD. Moreover, electron transport chain complex (I, V) decrease in FECD indicated deficient mitochondrial bioenergetics. Transmission electron microscopy of FECD tissues displayed an increased number of autophagic vacuoles containing degenerated and swollen mitochondria with cristolysis. An elevation of LC3-II and LAMP1 and downregulation of Mfn2 in mitochondrial fractions suggested that loss of fusion capacity targets fragmented mitochondria to the pre-autophagic pool and upregulates mitophagy. CCCP-induced mitochondrial fragmentation leads to Mfn2 and LC3 co-localization without activation of proteosome, suggesting a novel Mfn2 degradation pathway via mitophagy. These data indicate constitutive activation of mitophagy results in reduction of mitochondrial mass and abrogates cellular bioenergetics during degeneration of post-mitotic cells of ocular tissue.

Hydroxypropyl methylcellulose 2% for dry eye prevention during phacoemulsification in senile and diabetic patients.

To assess the effect of hydroxypropyl methylcellulose (HPMC) 2% to prevent dry eye during phacoemulsification in senile and diabetic patients. This prospective interventional case series comprised 60 eyes (44 patients) with age-related cataract scheduled for standardized phacoemulsification surgery. The patients were assigned to receive either balanced saline solution (BSS, 30 eyes) or HPMC 2% (30 eyes) during surgery. Preoperative and postoperative examinations (1, 3, 7 and 30days) included measurements of automatic noninvasive tear film breakup time (NITBUT), fluorescein staining, Schirmer I test, tear meniscus height, depth and area and subjective symptoms. Intraoperative application frequency was also assessed. The mean age of patients was 68.7±2.3years. The application frequency of BSS during surgery was significantly reduced in HPMC group (P=0.001). The incidence of dry eye syndrome (DES) was significantly reduced in HPMC group in both senile and diabetic patients. Scores of subjective symptoms were significantly higher in the BSS group in 1day (P=0.003) and 3days (P=0.043) postoperatively. The first and average NITBUT were significantly higher in HPMC group in 1day and 3days after surgery, respectively (P=0.012 and P=0.024, respectively). NITBUT values did not significantly change postoperatively in the HPMC group (P>0.05), while they were significantly lower postoperatively in the BSS group. Application of HPMC 2% during phacoemulsification reduced the incidence of DES and improved patients' satisfaction in both senile and diabetic cataract patients. It was also effective in maintaining corneal hydration and was able to significantly reduce the application frequency intraoperatively.

New parameters for evaluating corneal biomechanics and intraocular pressure after small-incision lenticule extraction by Scheimpflug-based dynamic tonometry

To evaluate parameters and dynamic corneal densitometry with a new dynamic Scheimpflug analyzer (Corvis ST) in eyes having small-incision lenticule extraction (SMILE). Qvision, Vithas Virgen del Mar Hospital, Almería, Spain. Retrospective case series. The study comprised eyes from the same institution having small-incision lenticule extraction surgery. Preoperative and 1-month postoperative measurements were taken. Forty-three eyes were evaluated. The mean difference inintraocular pressure (IOP) and biomechanically corrected IOP before and after surgery was 2.24mm Hg±1.26mm (SD) (P=.001) and 0.57±1.77mm Hg (P=.04), respectively. All dynamicScheimpflug analyzer parameters changed significantly after surgery (P<.05). The variation in each parameter was correlated with the removed corneal thickness (P<.05), except the stiffness parameter at the first applanation (P=.15). None of the 4 dynamic corneal densitometry parameters changed significantly as a resultof surgery (P≥.29). A new sign, described as an inclined brightnessfringe moving through the corneal periphery, appeared preoperatively in eyes with higher dynamic corneal densitometry. This sign was more prevalent postoperatively (48.8% versus 72.1%) (P=.04). The biomechanically corrected IOP measured after surgery with the dynamic Scheimpflug analyzer showed better agreement with the preoperative values than IOP. The stiffness parameter was not dependent on the amount of removed corneal thickness. A new sign correlated with dynamic corneal densitometry was found and might be related to changes in corneal hydration and biomechanics.

The structural response of the cornea to changes in stromal hydration.

The primary aim of this study was to quantify the relationship between corneal structure and hydration in humans and pigs. X-ray scattering data were collected from human and porcine corneas equilibrated with polyethylene glycol (PEG) to varying levels of hydration, to obtain measurements of collagen fibril diameter, interfibrillar spacing (IFS) and intermolecular spacing. Both species showed a strong positive linear correlation between hydration and IFS2 and a nonlinear, bi-phasic relationship between hydration and fibril diameter, whereby fibril diameter increased up to approximately physiological hydration, H = 3.0, with little change thereafter. Above H = 3.0, porcine corneas exhibited a larger fibril diameter than human corneas (p < 0.001). Intermolecular spacing also varied with hydration in a bi-phasic manner but reached a maximum value at a lower hydration (H = 1.5) than fibril diameter. Human corneas displayed a higher intermolecular spacing than porcine corneas at all hydrations (p < 0.0001). Human and porcine corneas required a similar PEG concentration to reach physiological hydration, suggesting that the total fixed charge that gives rise to the swelling pressure is the same. The difference in their structural responses to hydration can be explained by variations in molecular cross-linking and intra/interfibrillar water partitioning.

Identification of Prdm genes in human corneal endothelium

Corneal endothelial cells (CECs) are essential for maintaining corneal stromal hydration and ensuring its transparency, which is necessary for normal vision. Dysfunction of CECs leads to stromal decompensation, loss of transparency and corneal blindness. Corneal endothelium has low proliferative potential compared to surface epithelial cells leading to poor regeneration of CEC following injury. Additionally, the tissue exhibits age related decline in endothelial cell density with re-organisation of the cell layer, but no regeneration. The mechanisms which control proliferation and differentiation of neural crest derived CEC progenitors are yet to be clearly elucidated.Prdm (Positive regulatory domain) family of transcriptional regulators and chromatin modifiers are important for driving differentiation of a variety of cellular types. Many Prdm proteins are expressed in specific precursor cell populations and are necessary for their progression to a fully differentiated phenotype. In the present work, we sought to identify members of the Prdm gene family which are specifically expressed in human (h) CECs with a view to begin addressing their potential roles in CEC biology, focussing especially on Prdm 4 and 5 genes. By performing semi-quantitative reverse transcription coupled to PCR amplification we found that in addition to Prdm4 and Prdm5, Prdm2 and Prdm10 genes are expressed in hCECs. We further found that cultured primary hCECs or immortalised HCEC-12 cells express all of the Prdm genes found in CECs, but also express additional Prdm transcripts. This difference is most pronounced between Prdm gene expression patterns of CECs isolated from healthy human corneas and immortalised HCEC-12 cells. We further investigated Prdm 4 and Prdm 5 protein expression in cultured primary hCECs and HCEC-12 cells as well as in a human cadaveric whole cornea. Both Prdm 4 and Prdm 5 are expressed in human corneal endothelium, primary hCECs and in HCECs-12 cells, characterised by expression of the Na+/K+-ATPase. We observed that both proteins exhibit cytosolic (intracellular, but non-nuclear and distinct from extracellular fluid) as well as nuclear localisation within the endothelial layer, with Prdm 5 being more concentrated in the nuclei of the endothelial cells than Prdm 4. Thus, our work identifies novel Prdm genes specifically expressed in corneal endothelial cells which may be important in the control of CEC differentiation and proliferation.

Molecular Hydrogen Effectively Heals Alkali-Injured Cornea via Suppression of Oxidative Stress.

The aim of this study was to examine the effect of molecular hydrogen (H2) on the healing of alkali-injured cornea. The effects of the solution of H2 in phosphate buffered saline (PBS) or PBS alone topically applied on the alkali-injured rabbit cornea with 0.25 M NaOH were investigated using immunohistochemical and biochemical methods. Central corneal thickness taken as an index of corneal hydration was measured with an ultrasonic pachymeter. Results show that irrigation of the damaged eyes with H2 solution immediately after the injury and then within next five days renewed corneal transparency lost after the injury and reduced corneal hydration increased after the injury to physiological levels within ten days after the injury. In contrast, in injured corneas treated with PBS, the transparency of damaged corneas remained lost and corneal hydration elevated. Later results—on day 20 after the injury—showed that in alkali-injured corneas treated with H2 solution the expression of proinflammatory cytokines, peroxynitrite, detected by nitrotyrosine residues (NT), and malondialdehyde (MDA) expressions were very low or absent compared to PBS treated injured corneas, where NT and MDA expressions were present. In conclusion, H2 solution favorably influenced corneal healing after alkali injury via suppression of oxidative stress.

Investigation of opacity development in the human eye for estimation of the postmortem interval

Estimation of the postmortem interval (PMI) has attracted the attention of many researchers. It is generally accepted as a challenging task in forensic medicine. Due to its difficulty, researchers have tried to estimate the PMI using different physical and chemical techniques. Since the PMI estimation accuracies of previous studies are not at the desired level, new methods should be developed to more accurately estimate the PMI. The development of opacity in the eye in the PMI might be an important breakthrough in this field. After death, corneal hydration occurs due to degenerated endothelial cells. The degenerated endothelial barrier of the cornea cannot prevent the flow of aqueous humor to the cornea, which results in opacity. The amount of aqueous humor in the cornea determines the level of opacity. Since the flow of aqueous humor to the cornea will continue for a while, opacity is expected to increase with the PMI. In this study, images of human eyes were investigated using computer-based image analysis. The corneal and non-corneal opacities of the recorded eye images increase during the experiment. The experimental results prove that there is a correlation between the elapsed time after death and the development of opacity in the corneal and non-corneal regions in human cases. Exponential curve fitting is employed to observe the decay of the opacity over time. A repeated ANOVA test is also used to show that the opacity development is statistically significant.

Effects of oral intake of heat-killed Lactobacillus brevis SBC8803 (SBL88™) on dry skin conditions: A randomized, double-blind, placebo-controlled study.

Lactobacilli are important in intestinal homeostasis, which involves the regulation of immune function, digestive health, cholesterol absorption and intestinal tumor growth amongst others. Our previous investigations have suggested that oral intake of heat-killed Lactobacillus brevis (L. brevis) SBC8803 (SBL88™) suppresses dermatitis by modulating the immune function in an atopic dermatitis mouse model. The aim of the present study was to investigate the effect of heat-killed L. brevis SBC8803 intake on skin hydration conditions in humans. A randomized, double-blind, placebo-controlled study was conducted with volunteers with slightly higher levels of transepidermal water loss (TEWL) on the forearm. The subjects (126 people aged between 21 and 59 years) were randomly allocated to three groups so that the level of TEWL and the age were distributed equally among the groups. The subjects took placebo or heat-killed L. brevis SBC8803 at a daily dose of 25 or 50 mg for 12 weeks. Following the exclusion of eight subjects for plausible reasons (two withdrawals from the study, two for study violations, one for not meeting exclusion criteria and three due to their physical condition), 118 subjects were subjected to the analysis. The results of the present study revealed that following the analysis of the whole populations, marginal differences were observed in TEWL (for example, suppression of skin water loss) at the neck in the 25 mg/day group at week 8 and at the lower eye region in the 50 mg/day group at week 4 (P=0.05 and 0.09, respectively, compared with the placebo group analyzed by Dunnett's test). A significant increase in corneal hydration was also observed at the neck in the 25 mg/day group at week 12 (P=0.06, as compared with the placebo group as analyzed by Dunnett's test). In the analysis of the subpopulations whose habitual frequency of taking lactic fermentation products was less than once per week, the levels of corneal hydration at the neck (in the 50 mg/day group) and lower eye region (in the 25 mg/day group) were significantly increased at week 12 (P<0.05). In conclusion, the results of the present investigation suggest that oral intake of heat-killed L. brevis SBC8803 is effective at improving skin hydration conditions in populations with low habitual frequency of taking lactic fermentation products.

Corneal Hydration Control in Fuchs' Endothelial Corneal Dystrophy.

PurposeTo assess corneal hydration control across a range of severity of Fuchs' endothelial corneal dystrophy (FECD) by measuring the percent recovery per hour (PRPH) of central corneal thickness after swelling the cornea and to determine its association with corneal morphologic parameters.MethodsTwenty-three corneas of 23 phakic FECD patients and 8 corneas of 8 healthy control participants devoid of guttae were graded (modified Krachmer scale). Effective endothelial cell density (ECDe) was determined from the area of guttae and local cell density in confocal microscopy images. Steady-state corneal thickness (CTss) and standardized central corneal backscatter were derived from Scheimpflug images. Corneal swelling was induced by wearing a low-oxygen transmissible contact lens for 2 hours in the morning. De-swelling was measured over 5 hours after lens removal or until corneal thickness returned to CTss. Percent recovery per hour was 100 × (1 – e−k), where k was determined from CT(t) = (de−kt) + CTss, and where d was the initial change from CTss.ResultsAfter contact lens wear, corneas swelled by 9% (95% CI 9–10). Percent recovery per hour was 49%/h (95% CI 41–57) in controls and 37%/h in advanced FECD (95% CI 29–43, P = 0.028). Low PRPH was associated with disease severity, low ECDe, and increased anterior and posterior corneal backscatter. Anterior backscatter was associated with PRPH in a multivariable model (R2 = 0.44).ConclusionsCorneal hydration control is impaired in advanced FECD and is inversely related to anterior corneal backscatter. Anterior corneal backscatter might serve as an indicator of impaired endothelium in FECD.