In Situ Gelling Electrospun Ocular Films Sustain the Intraocular Pressure-Lowering Effect of Timolol Maleate: In Vitro, Ex Vivo, and Pharmacodynamic Assessment.

Most common intraocular pressure (IOP) reduction regimens for the management of glaucoma include the topical use of eye drops, a dosage form that is associated with short residence time at the site of action, increased dosing frequency, and reduced patient compliance. In situ gelling nanofiber films comprising poly(vinyl alcohol) and Poloxamer 407 were fabricated via electrospinning for the ocular delivery of timolol maleate (TM), aiming to sustain the IOP-lowering effect of the ß-blocker, compared to conventional eye drops. The electrospinning process was optimized, and the physicochemical properties of the developed formulations were thoroughly investigated. The fiber diameters of the drug-loaded films ranged between 123 and 145 nm and the drug content between 5.85 and 7.83% w/w. Total in vitro drug release from the ocular films was attained within 15 min following first-order kinetics, showing higher apparent permeability (Papp) values across porcine corneas compared to the drug's solution. The fabricated films did not induce any ocular irritation as evidenced by both the hen's egg test on chorioallantoic membrane and the in vivo Draize test. In vivo administration of the ocular films in rabbits induced a faster onset of action and a sustained IOP-lowering effect up to 24 h compared to TM solution, suggesting that the proposed ocular films are promising systems for the sustained topical delivery of TM.

New application for assessment of dry eye syndrome induced by particulate matter exposure.

Dry eye syndrome (DES) is a multifactorial condition characterized by insufficient tear lubrication and eye irritation. Air pollutants, including particulate matter (PM), are an emerging threat to human health causing DES and other diseases. However, the pathogenic mechanisms of DES induced by PM exposure remain to be fully elucidated. Recent studies have attempted to create DES animal model using PM exposure. In this study, we explored a novel in vivo exposure model of DES, utilizing an inhalation device (aerosol exposure system) to reproduce the natural exposure to atmospheric PM. Rats were exposed to urban PM (UPM) using this aerosol system for 5 h per day over 5 days. Tear volume in UPM-exposed rats decreased significantly, whereas corneal irregularity and lissamine green staining significantly increased following UPM exposure. Additional effects observed following UPM exposure included apoptosis in the corneal epithelium and a decrease in the number of goblet cells in the conjunctiva. UPM also affected the stability of the tear film by disrupting its mucin-4 layer. In conclusion, aerosol exposure systems have proven effective as assessment tools for DES caused by PM.

Rapid assessment of ocular drug delivery in a novel ex vivo corneal model.

Drug delivery by topical application has higher patient acceptance and lower morbidity than intraocular injection, but many ophthalmic treatments are unable to enter the eye or reach the posterior segment after topical application. The first stage towards posterior segment delivery after topical application is ocular surface penetration and existing models are in vivo or use large quantities of tissue. We therefore developed a novel ex vivo model using discs of porcine and human cornea and sclera (5 mm diameter) to assess penetration of a candidate neuroprotective siRNA. siRNA against caspase 2 or control solutions of known penetrance were applied to the corneal epithelial surface and trans-corneal penetration and corneal adsorbance measured at fixed time points. To demonstrate that leakage did not occur, we applied dextran blue, which should not penetrate the intact cornea and did not do so in our model. Fluorescein penetration (0.09%) was less than rhodamine B (6.98%) at 60 min. siCASP2 penetration was 0.01% by 60 min. When the applied siCASP2 was washed off after 2 min, (representing lacrimal drainage) 0.071% penetrated porcine cornea by 60 min and 0.0002% penetrated human cornea and 0.001% penetrated human sclera. Our ex vivo model rapidly and cost-effectively assesses transcorneal penetration of candidate topical therapies, allowing rates of trans-corneal penetration for potential therapies such as siRNA to be evaluated with small quantities of human or animal tissue.

Amelioration from the ocular irritant Capsaicin: development and assessment of a Capsazepine in situ gel system for ocular delivery.

BACKGROUND: Defense personnel utilize capsaicin-based ocular sprays as non-lethal agents for law implementation during instances of mob violence. This study involves the capsaicin antagonist Capsazepine and the investigation of whether Capsazepine's antagonistic approach can be favorably utilized for defense utilization to block capsaicin-initiated pain and inflammation via the ocular pathway. RESEARCH DESIGN AND METHODS: Ocular capsazepine in situ gels were prepared with polymers Pluronic F-127 and Chitosan; optimized formulation was quantified in ocular tissues chromatographically and by in vivo live ocular imaging; anti-inflammatory efficacy was determined by eye irritation testing, corneal and retinal imaging, ocular prostaglandin estimation, and by viability and proliferation testing using human ocular cell lines, etc. RESULTS: A physicochemically stable Capsazepine in situ gel was formulated which showed little ocular irritation, considerable transcorneal permeation; was precisely quantified in ocular tissues by gas chromatography and in vivo live ocular imaging; showed anti-inflammatory properties against capsaicin by eye imaging experiments, prostaglandin declination and showed acceptable cytocompatibility when studied using human ocular cell lines. CONCLUSIONS: The fabricated in situ Capsazepine gel system might be promising for ocular delivery as it appears a pharmacologically potent and safe development, suitable for utilization in the ocular clinical therapy, provided there is additional research to substantiate it.

Innovative strategy based on mechanisms to substitute animal testing for ocular toxicity assessment of agrochemical formulations market in Brazil.

Considering the successful employment of alternative methods for eye toxicity assessment of products for regulatory purposes, and the recent advances in Brazilian legislative scenario, which adopted the UN GHS classification system for agrochemical formulations toxicity assessment, there is an emerging demand for strategies that allow the evaluation of such products. Based on this, the present study aimed to address the applicability of a mechanistic-based defined approach for eye toxicity assessment of agrochemical formulations. It was investigated the opacity/permeability, depth and location of corneal injury in bovine cornea, and vascular events in chorioallantoic membrane induced for different Brazilian agrochemicals using a Sequential Testing Strategy (STS). Cytotoxicity induced by the agrochemical formulations was evaluated by Short Time exposure (STE) (OECD TG 491) assay (step 1), corneal injury was investigated by standard Bovine Corneal Opacity and Permeability (BCOP) (OECD TG 437) followed by histopathological evaluation (step 2), and Hen Chorionic-allantoic Membrane test (HET-CAM) was used to evaluate vascular injury (step 3). The results demonstrated that the proposed defined approach enabled a classification corresponding UN GHS classification of agrochemical formulations while minimizing the use of live animals. Therefore, this approach may be useful for categorization of agrochemicals in Brazil according to the new regulatory scenario.

Nerve growth factor in dogs: Assessment of two immunoassays and selected ocular parameters following a nicergoline challenge per os.

Impairment of corneal nerves can result in the development of ocular surface diseases such as aqueous tear deficiency and neurotrophic keratopathy. This study investigates oral nicergoline, an α-adrenoceptor antagonist shown to enhance endogenous secretion of nerve growth factor (NGF) by the lacrimal gland, as a potential therapy for these conditions. Five female spayed Beagle dogs received a 2-week course of oral nicergoline (10 mg twice daily). Drug safety was evaluated with ophthalmic and physical examinations, blood pressure monitoring, bloodwork, and urinalysis. The effect of nicergoline on the ocular surface was assessed with corneal esthesiometry, Schirmer tear test-1, and tear film breakup time. Drug effect on NGF levels was assessed by collecting tears and blood at baseline and completion of therapy using a bead-based immunoassay and an enzyme-linked immunosorbent assay. Although nicergoline was well tolerated in all dogs, it did not have a significant impact on corneal sensitivity, tear production, or tear stability. Of note, NGF was below the limit of quantification in all tear samples and was only detected in 8/20 serum samples with no significant difference between levels at baseline (189.4 ± 145.1 pg/mL) and completion of therapy (149.4 ± 79.4 pg/mL). Further validation of NGF analytical assays is warranted before nicergoline is investigated in clinical patients.

Noninvasive assessment of corneal alterations associated with monoclonal gammopathy.

Aggregation of monoclonal immunoglobulin can lead to organ damage. However, the necessity of invasive examination such as biopsy has hampered better understanding of the pathophysiology. Corneal crystalline deposition is a rarely reported but known ocular manifestation of multiple myeloma. It is unclear whether the cornea is a common target of monoclonal immunoglobulin deposition. We conducted a prospective clinical case-control study to objectively quantify monoclonal gammopathy-associated corneal changes as well as any therapeutic response. Using an ophthalmic Scheimpflug camera imaging for noninvasive corneal assessments, we quantified densitometry values in 30 patients. Although none had crystalline keratopathy, corneal transparency in monoclonal gammopathy patients was significantly impaired compared to that in age-matched controls, based on noninvasive Scheimpflug camera imaging. Furthermore, treatment for multiple myeloma seemed to eradicate the diffuse aggregation of monoclonal proteins. Our results indicate that exposure to monoclonal immunoglobulin may induce the accumulation of monoclonal immunoglobulin in the cornea, and ophthalmic examinations such as corneal densitometry measurements with a Scheimpflug camera may be useful for noninvasive evaluation of monoclonal immunoglobulin deposition diseases.

DenTimol as A Dendrimeric Timolol Analogue for Glaucoma Therapy: Synthesis and Preliminary Efficacy and Safety Assessment.

In this work, we report the synthesis and characterization of DenTimol, a dendrimer-based polymeric timolol analog, as a glaucoma medication. A timolol precursor ( S)-4-[4-(oxiranylmethoxy)-1,2,5-thiadiazol-3-yl]morpholine (OTM) was reacted with the heterobifunctional amine polyethylene glycol acetic acid (amine-PEG-acetic acid, Mn = 2000 g/mol) via a ring opening reaction of an epoxide by an amine to form the OTM-PEG conjugate. OTM-PEG was then coupled to an ethylenediamine (EDA) core polyamidoamine (PAMAM) dendrimer G3 to generate DenTimol using the N-(3-(dimethylamino)propyl)- N'-ethylcarbodiimide hydrochloride (EDC)/ N-hydroxysuccinimide (NHS) coupling reaction. MALDI mass spectrometry, 1H NMR spectroscopy, and HPLC were applied to characterize the intermediate and final products. Ex vivo corneal permeation of DenTimol was assessed using the Franz diffusion cell system mounted with freshly extracted rabbit cornea. The cytotoxicity of DenTimol was assessed using the WST-1 assay. Our results show that DenTimol is nontoxic up to an OTM equivalent concentration of 100 µM. DenTimol is efficient at crossing the cornea. About 8% of the dendrimeric drug permeated through the cornea in 4 h. Its IOP-lowering effect was observed in normotensive adult Brown Norway male rats. Compared to the undosed eye, an IOP reduction by an average of 7.3 mmHg (∼30% reduction from baseline) was observed in the eye topically treated with DenTimol (2 × 5 µL, 0.5% w/v timolol equivalent) in less than 30 min. Daily dosing of DenTimol for a week did not cause any irritation or toxicity as confirmed by the histological examination of ocular tissues, including the cornea, ciliary body, and retina.

Paradox response of cornea to different color intensities of visible light: An experimental study.

The technological development is associated with human daily life and had an impact on its social life. Due to the difficulty of estimating the daily exposure to light; research is needed to determine how much natural and man-made lights could affect the cornea. Visible light radiation could have damaging effect on the human eye; the type and degree of damage are related to the duration and the cumulative exposure as well as to the intensity of the rays. There are noticeable increases in using electronic devices and colored lamps in decoration and toys as well, without any specific regulation. We studied the effect of such human activity on the corneal structure and the vibrational characteristics of corneal tissue by Fourier transform infrared spectroscopy. To achieve these goals, Chinchilla rabbits were exposed to two different lux of blue, green or red color lamps. The results indicate that the corneal tissue responds non-specifically to each lux and accordingly the color. The detected changes are including corneal protein secondary structure as well as lipids, in particular phospholipids. This was concomitant with more ordered membrane bilayer and changes in the corneal membrane phase organization. No lux/color-response relationship was established.

Agreement and repeatability of objective systems for assessment of the tear film.

PURPOSE: To assess the agreement and repeatability of two objective systems for measuring the tear film stability. METHODS: Retrospective analysis of the tear film stability of 99 healthy right eyes measured with a videokeratoscope (VK) and the Optical Quality Analysis System (OQAS, Visiometrics). Two consecutive measures were taken with both systems, with an interval of 10 min between them. Variables included in the study were first and mean non-invasive break-up times (NIBUT and MNIBUT) measured with VK, and mean and standard deviation of the optical scattering index (OSIm and OSIsd) measured with OQAS. The agreement and repeatability of grading scales provided by both devices were also evaluated using the Cohen's k with quadratic weights. The Ocular Surface Disease index (OSDI) questionnaire was also passed out to all subjects. Correlations and associations between subjective and objective metrics were analyzed. RESULTS: Significant differences were found between consecutive measurements of NIBUT (p = 0.04) and MNIBUT (p = 0.01), but not for OSIm (p = 0.11) and OSIsd (p = 0.50). Grading scales resulted in fair (k = 0.20) or poor agreement (k = 0.04) between systems depending if the first or second trial was considered. The repeatability of the grading scale was good for OQAS (k = 0.59) and fair for VK (k = 0.37). No significant correlations or associations were found between OSDI and any of the metrics obtained with both devices (p ≥ 0.36). CONCLUSIONS: The two devices evaluated cannot be used interchangeably for the assessment of tear film stability. Good intrasession repeatability was obtained for tear film grading of the OQAS whereas it was fair for VK.

Assessment of the metabolism and morphology of the porcine cornea, lens and retina by 2-photon imaging.

Two-photon imaging is a noninvasive imaging technique with increasing importance in the biological and medical fields since it allows intratissue cell imaging with high resolution. We demonstrate the feasibility of using a single 2-photon instrument to evaluate the cornea, the crystalline lens and the retina based on their autofluorescence (AF). Image acquisition was performed using a custom-built 2-photon microscope for 5-dimensional microscopy with a near infrared broadband sub-15 femtosecond laser centered at 800 nanometers. Signals were detected using a spectral photomultiplier tube. The spectral ranges for the analysis of each tissue/layer AF were determined based on the spectra of each tissue as well as of pure endogenous fluorophores. The cornea, lens and retina are characterized at multiple depths with subcellular resolution based on their morphology and AF lifetime. Additionally, the AF lifetime of NAD(P)H was used to assess the metabolic activity of the cornea epithelium, endothelium and keratocytes. The feasibility to evaluate the metabolic activity of lens epithelial cells was also demonstrated, which may be used to further investigate the pathogenesis of cataracts. The results illustrate the potential of multimodal multiphoton imaging as a novel ophthalmologic technique as well as its potential as a diagnostic tool.

In vitro and in vivo assessment of delivery of hydrophobic molecules and plasmid DNAs with PEO-PPO-PEO polymeric micelles on cornea.

The stability and bio-distribution of genes or drug complexes with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, Pluronic F-68) polymeric micelles (PM) are essential for an effective nanosized PM delivery system. We used Förster resonance energy transfer (FRET) pairs with PM and measured the FRET ratio to assess the stability of PM in vitro and in vivo on the cornea. The FRET ratio reached a plateau at 0.8 with 3% PM. Differential scanning calorimetry measurement confirmed the complex formation of FRET pairs with PM. Confocal imaging with the fluorophores fluorescein isothiocyanate isomer I (FITC) and rhodamine B base (RhB) also showed the occurrence of FRET pairs in vitro. The fluorophores were mixed with 3% PM solution or the FITC-labeled PEO-PPO-PEO polymers (FITC-P) were mixed with RhB-labeled plasmids (RhB-DNA). In addition, the in vitro corneal permeation of FRET pair complexes with PM reached a 0.8 FRET ratio. One hour after eye drop administration, FRET pairs colocalized in the cytoplasm, and surrounded and entered the nuclei of cells in the cornea, and the polymers were located in the corneal epithelial layers, as detected through anti-PEG immunohistochemistry. Furthermore, fluorescence colocalization in the cytoplasm and cell nucleus of the corneal epithelium was confirmed in tissues where RhB or RhB-DNA complexed with FITC-P was found to accumulate. We demonstrate that at a concentration of 3%, PM can encapsulate FRET pairs or RhB-DNA and retain their integrity within the cornea 1 h after administration, suggesting the feasibility and stability of PEO-PPO-PEO polymers as a vehicle for drug delivery.

Non-invasive optical method for real-time assessment of intracorneal riboflavin concentration and efficacy of corneal cross-linking.

Keratoconus is the primary cause of corneal transplantation in young adults worldwide. Riboflavin/UV-A corneal cross-linking may effectively halt the progression of keratoconus if an adequate amount of riboflavin enriches the corneal stroma and is photo-oxidated by UV-A light for generating additional cross-linking bonds between stromal proteins and strengthening the biomechanics of the weakened cornea. Here we reported an UV-A theranostic prototype device for performing corneal cross-linking with the ability to assess corneal intrastromal concentration of riboflavin and to estimate treatment efficacy in real time. Seventeen human donor corneas were treated according to the conventional riboflavin/UV-A corneal cross-linking protocol. Ten of these tissues were probed with atomic force microscopy in order to correlate the intrastromal riboflavin concentration recorded during treatment with the increase in elastic modulus of the anterior corneal stroma. The intrastromal riboflavin concentration and its consumption during UV-A irradiation of the cornea were highly significantly correlated (R = 0.79; P = .03) with the treatment-induced stromal stiffening effect. The present study showed an ophthalmic device that provided an innovative, non-invasive, real-time monitoring solution for estimating corneal cross-linking treatment efficacy on a personalized basis.

Dry Eye Assessment in Patients With Vitiligo.

PURPOSE: To evaluate tear osmolarity and tear film parameters in patients with vitiligo. METHODS: A total of 25 eyes of 25 patients with vitiligo with periocular involvement (group 1), 30 eyes of 30 patients with vitiligo without periocular involvement (group 2), and 20 eyes of 20 controls (group 3) were evaluated using the Ocular Surface Disease Index (OSDI) questionnaire, Schirmer I test, tear film breakup time, scoring of ocular surface fluorescein staining using a modified Oxford scale, and tear osmolarity. RESULTS: Mean tear osmolarity was 332 ± 16.3 mOsm/L in group 1, 308.8 ± 19.5 mOsm/L in group 2, and 286.3 ± 23.4 mOsm/L in group 3 (P < 0.001). There was no significant difference in Schirmer I test results among the 3 groups (16.5 ± 3.2 mm in group 1, 16.3 ± 4.7 mm in group 2, and 17.4 ± 4.2 mm in group 3) (P = 0.175). Tear film breakup time measurements in groups 1 (9.8 ± 3.5 seconds) and 2 (10.1 ± 4.3 seconds) were significantly lower than those in group 3 (18.5 ± 4.0 seconds) (P < 0.001). There was no significant difference among the 3 groups on the Oxford scale (0.04 ± 0.70 in group 1, 0.03 ± 0.33 in group 2, and 0.03 ± 0.20 in group 3) (P = 0.865). The mean Ocular Surface Disease Index score was significantly higher in groups 1 and 2 than in group 3 (42.1 ± 16.5 in group 1, 39.9 ± 17.3 in group 2, and 12.3 ± 11.6 in group 3) (P < 0.001). CONCLUSIONS: This study showed that vitiligo is associated with tear hyperosmolarity and tear film dysfunction. Patients with vitiligo with periocular involvement may be more prone to dry eye than those without ocular involvement.

Assessment of Topical Therapies for Improving the Optical Clarity Following Stromal Wounding in a Novel Ex Vivo Canine Cornea Model.

Purpose: To evaluate the effect of topical suberanilohydroxamic acid (SAHA) and 5-methyl-1-phenyl-2[1H]-pyridone (pirfenidone) on the degree of corneal haze in the stromal wounded ex vivo canine cornea. Methods: Twenty-four corneoscleral rims from normal dogs were uniformly wounded with an excimer laser and placed into culture medium with an air-liquid interface. The control group (n = 8) contained placebo-treated corneas. Treatment group 1 (n = 8) received SAHA topically every 6 hours. Treatment group 2 (n = 8) received pirfenidone topically every 6 hours. Each cornea was fluorescein stained and macrophotographed every 6 hours to assess epithelialization rate. All corneas were also macrophotographed weekly to assess optical clarity (haze). Images were analyzed for differences in pixel intensity between wounded (haze) and unwounded (nonhaze) regions, and haze surface area for each cornea was calculated. Results: The mean epithelialization time was 47.25 hours in the control group, 45.00 hours in the SAHA group, and 43.50 hours in the pirfenidone group, revealing no significant difference (P = 0.368). The median difference in pixel intensity between haze and nonhaze areas was 21.5 in the control group, 8.0 in the SAHA group, and 8.0 in the pirfenidone group, which is significant (P < 0.01). The median haze surface area was 12.96 mm2 in the control group, 5.70 mm2 in the SAHA group, and 5.92 mm2 in the pirfenidone group, which is significant (P < 0.01). Conclusions: Stromal-wounded ex vivo canine corneas exhibited greater optical clarity when treated with SAHA and pirfenidone than when placebo treated at 21 days. There was no significant difference in epithelialization rate between groups. Corneal contour was correlated with geographic haze distribution.

Novel Assay Assessment of Oxidative Stress Biomarkers in Patients with Keratoconus: Thiol-Disulfide Homeostasis.

PURPOSE: To investigate systemic oxidative stress by evaluating thiol-disulfide homeostasis using a novel automated homeostasis assay in keratoconus patients. METHODS: Twenty-eight patients with keratoconus and 30 control subjects of a similar age and gender were enrolled in the present study. The native thiol, total thiol, and disulfide levels and the disulfide-native thiol, disulfide-total thiol, and native thiol-total thiol ratios were analyzed and compared between the keratoconus and control groups using a novel automatized spectrophotometric assay. RESULTS: The median serum native thiol value was 441.5 (362.6-488.1) in the keratoconus group and 467.8 (401.8-564.6) in the control subjects. The median serum total thiol value was 467.9 (375-580.6) in the keratoconus group and 503.3 (437.7-578.5) in the control subjects. The median serum disulfide value was 20.1 (6.2-46.3) in the keratoconus patients and 16.7 (1.1-20.8) in the controls. There were significant differences between the native thiol, total thiol, and disulfide levels of the keratoconus patients and controls (p = 0.001, p = 0.04, and p = 0.03, respectively) and the disulfide-native thiol, disulfide-total thiol, and native thiol-total thiol ratios of these two groups (p = 0.02, p = 0.01, and p = 0.001, respectively). We found no significant correlation between age and any of the thiol-disulfide parameters (p > 0.05 for all values). CONCLUSIONS: There is an imbalance in the systemic thiol-disulfide homeostasis in KC patients. This metabolic imbalance may play an important role in the pathogenesis of keratoconus; thus, it can be discussed in terms of the prevention, diagnosis, and the possible treatment for keratoconus.

Automated Measurement of Tear Film Dynamics and Lipid Layer Thickness for Assessment of Non-Sjögren Dry Eye Syndrome With Meibomian Gland Dysfunction.

PURPOSE: To investigate automated values from an advanced corneal topographer with a built-in real keratometer, color camera, and ocular surface interferometer for the evaluation of non-Sjögren dry eye syndrome (NSDES) with meibomian gland dysfunction (MGD). METHODS: Sixty-four patients (64 eyes) diagnosed with NSDES with MGD were enrolled. All eyes were evaluated using the Ocular Surface Disease Index (OSDI), fluorescence staining score, tear film breakup time (TBUT), Schirmer test, and MGD grade. Noninvasive Keratograph average tear film breakup time (NIKBUTav), tear meniscus height (TMHk), meibomian gland (MG) dropout grade, and lipid layer thickness (LLT) using interferometry were measured. RESULTS: Among automated indexes, NIKBUTav (mean 7.68 ± 4.07 s) and the MG dropout grade (mean 1.0 ± 0.5) significantly correlated with the OSDI (mean 40.6 ± 22.9) (r = -0.337, P = 0.006; and r = 0.201, P = 0.023, respectively), as did all conventional indicators, except the Schirmer score (mean 9.1 ± 5.9 mm). TMHk (mean 0.21 ± 0.18 mm) had significant correlation with the Schirmer score, the staining score (mean 1.2 ± 0.7), TBUT (mean 3.8 ± 1.8 s), and NIKBUTav (r = 0.298, P = 0.007; r = -0.268, P = 0.016; r = 0.459, P < 0.001; and r = 0.439, P < 0.001, respectively), but not any MGD indicator, even the MG dropout grade. NIKBUTav showed significant correlations with all clinical parameters and other automated values, except the Schirmer score and LLT (mean 83.94 ± 20.82 nm) (all (Equation is included in full-text article.)≥ 0.25 and P < 0.01). The MG dropout grade highly correlated with all indexes except TMHk (all (Equation is included in full-text article.)≥ 0.25 and P < 0.05). LLT was significantly associated with TBUT, MGD grade (mean 2.0 ± 0.7), and MG dropout grade (r = 0.219, P = 0.047; r = -0.221, P = 0.039; and r = 0.433, P < 0.001, respectively), although it was not related to patient symptoms. CONCLUSIONS: Automated noninvasive measurements using an advanced corneal topographer and LLT measured with an ocular surface interferometer can be alternatives to conventional methods to evaluate tear conditions on the ocular surface; the former device can provide information about conformational MG changes in NSDES with MGD.

Assessment of Corneal Parameters with Scheimpflug Imaging in Patients with Ankylosing Spondylitis.

PURPOSE: To evaluate corneal parameters of patients with ankylosing spondylitis (AS) by Scheimpflug imaging and also to clarify the associations between disease severity and clinical status of AS and corneal parameters. METHODS: Fifty-seven patients with AS and 57 healthy subjects were included in this cross-sectional study. All participants underwent a detailed ophthalmological evaluation. Corneal parameters were measured by Pentacam. In addition, Schirmer test, tear break-up time (TBUT), corneal fluorescein staining, and Ocular Surface Disease Index (OSDI) scores were evaluated. Duration of disease and scores of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Quality of Life scale (ASQoL) of the patients were recorded. The laboratory evaluation consisted of human leukocyte antigen (HLA)-B27, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). RESULTS: Corneal parameters were significantly different between patients with AS and healthy controls. The mean central corneal thickness (538 ± 26 µm versus 569 ± 27 µm, p < 0.001) and the mean corneal volume (59.8 ± 3.33 mm3 versus 62.3 ± 3.40 mm3, p < 0.001) were reduced significantly in AS patients compared to those in healthy controls. The values of TBUT and Schirmer test scores were significantly lower in AS patients than in controls. Also, corneal fluorescein staining and OSDI scores were higher in AS patients than in controls. Factors related to the corneal parameters were dry eye tests (TBUT, Schirmer test, corneal fluorescein staining), OSDI score, and CRP (p < 0.05 for all). CONCLUSION: The AS patients have thinner corneas compared to control subjects, which may be affected by tear disfunction and inflammatory processes.

Functional assessment of SLC4A11, an integral membrane protein mutated in corneal dystrophies.

SLC4A11, a member of the SLC4 family of bicarbonate transporters, is a widely expressed integral membrane protein, abundant in kidney and cornea. Mutations of SLC4A11 cause some cases of the blinding corneal dystrophies, congenital hereditary endothelial dystrophy, and Fuchs endothelial corneal dystrophy. These diseases are marked by fluid accumulation in the corneal stroma, secondary to defective fluid reabsorption by the corneal endothelium. The role of SLC4A11 in these corneal dystrophies is not firmly established, as SLC4A11 function remains unclear. To clarify the normal function(s) of SLC4A11, we characterized the protein following expression in the simple, low-background expression system Xenopus laevis oocytes. Since plant and fungal SLC4A11 orthologs transport borate, we measured cell swelling associated with accumulation of solute borate. The plant water/borate transporter NIP5;1 manifested borate transport, whereas human SLC4A11 did not. SLC4A11 supported osmotically driven water accumulation that was electroneutral and Na+ independent. Studies in oocytes and HEK293 cells could not detect Na+-coupled HCO3- transport or Cl-/HCO3- exchange by SLC4A11. SLC4A11 mediated electroneutral NH3 transport in oocytes. Voltage-dependent OH- or H+ movement was not measurable in SLC4A11-expressing oocytes, but SLC4A11-expressing HEK293 cells manifested low-level cytosolic acidification at baseline. In mammalian cells, but not oocytes, OH-/H+ conductance may arise when SLC4A11 activates another protein or itself is activated by another protein. These data argue against a role of human SLC4A11 in bicarbonate or borate transport. This work provides additional support for water and ammonia transport by SLC4A11. When expressed in oocytes, SLC4A11 transported NH3, not NH3/H.

Assessment of UVA-Riboflavin Corneal Cross-Linking Using Small Amplitude Oscillatory Shear Measurements.

PURPOSE: The effect of ultraviolet (UV)-riboflavin cross-linking (CXL) has been measured primarily using the strip extensometry technique. We propose a simple and reliable methodology for the assessment of CXL treatment by using an established rheologic protocol based on small amplitude oscillatory shear (SAOS) measurements. It provides information on the average cross-link density and the elastic modulus of treated cornea samples. METHODS: Three fresh postmortem porcine corneas were used to study the feasibility of the technique, one serving as control and two receiving corneal collagen cross-linking treatment. Subsequently, five pairs of fresh postmortem porcine corneas received corneal collagen cross-linking treatment with riboflavin and UVA-irradiation (370 nm; irradiance of 3 mW/cm2) for 30 minutes (Dresden protocol); the contralateral porcine corneas were used as control samples. After the treatment, the linear viscoelastic moduli of the corneal samples were measured using SAOS measurements and the average cross-linking densities extracted. RESULTS: For all cases investigated, the dynamic moduli of the cross-linked corneas were higher compared to those of the corresponding control samples. The increase of the elastic modulus of the treated samples was between 122% and 1750%. The difference was statistically significant for all tested samples (P = 0.018, 2-tailed t-test). CONCLUSIONS: We report a simple and accurate methodology for quantifying the effects of cross-linking on porcine corneas treated with the Dresden protocol by means of SAOS measurements in the linear regime. The measured dynamic moduli, elastic and viscous modulus, represent the energy storage and energy dissipation, respectively. Hence, they provide a means to assess the changing physical properties of the cross-linked collagen networks after CXL treatment.