Wnt/ß-catenin signaling stimulates the self-renewal of conjunctival stem cells and promotes corneal conjunctivalization.

Limbal stem cell deficiency causes conjunctivalization characterized by the covering of the corneal surface with conjunctival epithelium. However, the driving force for the encroachment of these conjunctival cells is unclear. Conjunctival stem cells are bipotent stem cells that can proliferate and differentiate into conjunctival epithelial cells and goblet cells to maintain regeneration of the conjunctival epithelium. Here, we show a robust proliferative response of conjunctival stem cells and upregulation of Wnt2b and Wnt3a gene expression in the conjunctivae of mice with induced limbal stem cell deficiency. Topical application of the Wnt/ß-catenin signaling activator CHIR resulted in increased proliferation of ΔNp63α-positive stem cells in the basal layers of the bulbar and forniceal conjunctivae and enhanced invasion of conjunctival epithelial and goblet cells into the corneal surface. We also found that in cultures of stem cells isolated from the human conjunctiva, Wnt/ß-catenin pathway activation improved the expansion of the ΔNp63α/ABCG2 double-positive cell population by promoting the proliferation and preventing the differentiation of these cells. These expanded stem cells formed a stratified epithelium containing goblet cells under airlift culture conditions. Our data reveal that Wnt/ß-catenin signaling contributes to the pathological process of limbal stem cell deficiency by promoting the self-renewal of conjunctival stem cells and suggest that these cells are a driving force in corneal conjunctivalization.

Quantitative measurement of optical properties and Hb concentration in a rodent model of inflammatory Meibomian gland dysfunction using spatial frequency domain imaging.

Herein, to investigate a new diagnostic method for Meibomian gland dysfunction (MGD) induced by eyelid inflammation, optical properties and deoxy-hemoglobin (Hb) concentrations in rodent eyelid tissues, including Meibomian glands(MGs), were measured using spatial frequency domain imaging (SFDI). Complete Freund's adjuvant solutions were injected into the eyelid margins of Sprague-Dawley rats to induce MGD. After three weeks, the optical properties and Hb of the MG and non-MG regions of the eyelids were measured ex-vivo using an SFDI system. The comparison of Hb showed that the MGD group exhibited significantly higher values than those of the control group in both regions. The optical properties at 730 and 850 nm for the MG regions in the MGD group were significantly different from those in the control group. In addition, the 630 nm absorption coefficients of both regions were significantly higher in the MGD group than in the control group. Thus, the SFDI technique can detect the increased Hb concentration and changes in the optical properties of the eyelids due to inflammatory MGD in a noncontact manner and has the potential to be used as a novel quantitative diagnostic method for the occurrence of MGD.

Development of the Integrated Glaucoma Risk Index.

Various machine-learning schemes have been proposed to diagnose glaucoma. They can classify subjects into 'normal' or 'glaucoma'-positive but cannot determine the severity of the latter. To complement this, researchers have proposed statistical indices for glaucoma risk. However, they are based on a single examination indicator and do not reflect the total severity of glaucoma progression. In this study, we propose an integrated glaucoma risk index (I-GRI) based on the visual field (VF) test, optical coherence tomography (OCT), and intraocular pressure (IOP) test. We extracted important features from the examination data using a machine learning scheme and integrated them into a single measure using a mathematical equation. The proposed index produces a value between 0 and 1; the higher the risk index value, the greater the risk/severity of glaucoma. In the sanity test using test cases, the I-GRI showed a balanced distribution in both glaucoma and normal cases. When we classified glaucoma and normal cases using the I-GRI, we obtained a misclassification rate of 0.07 (7%). The proposed index is useful for diagnosing glaucoma and for detecting its progression.

Effect of low-level light therapy in patients with dry eye: a prospective, randomized, observer-masked trial.

To evaluate the efficacy of low-level light therapy (LLLT) with near-infrared light-emitting diodes (LED-LLLT) for the treatment of dry eye. 40 patients were randomly assigned with a 1:1 allocation ratio to receive LED-LLLT (LLLT group, n = 20) or placebo treatment (placebo group, n = 20). Patients in the LLLT group received LLLT twice a week for 3 weeks, for a total of 6 treatment sessions. The primary endpoint was the changes in the fluorescein corneal staining (FCS) score. The secondary endpoints were the changes in the ocular surface disease index (OSDI) score, lissamine green conjunctival staining (LGCS) scores, tear film break-up time (TBUT), Schirmer test, and the meibomian gland dysfunction (MGD) index. These were evaluated before treatment and 4 weeks after start of treatment. The mean difference of score change in primary endpoint revealed significant improvement in the LLLT group, compared to the placebo. Among secondary endpoints, LGCS, Schirmer's test, upper meibography scores showed significant improvements, while TBUT, lid debris, lid swelling, lid telangiectasia, meibomian gland secretion and expressibility scores had slight improvement without significant differences. No serious adverse events were observed. The use of LED-LLLT for the treatment of dry eye and MGD appears to be safe and beneficial.

Posterior segment complications of Ahmed valve implantation.

BACKGROUND: To assess the time, incidence, and outcome of posterior segment complications of Ahmed valve implantation (AVI). METHODS: 248 eyes that underwent AVI were reviewed retrospectively. Visual acuity, preoperative characteristics, and postoperative posterior segment complications were assessed. RESULTS: The incidence of posterior segment complications of AVI was 31.4% (78/248). The mean follow-up period was 97.4 ± 53.5 months. The mean time to occur posterior segment complication was 1.5 months. The most common posterior segment complication was choroidal detachment (17.7%) and others included ocular decompression retinopathy (3.2%), hypotonic maculopathy (2.8%), vitreous hemorrhage (2.0%), retinal detachment (1.2%), endophthalmitis (1.2%), suprachoroidal hemorrhage (1.2%), epiretinal membrane (0.8%), cystoid macular edema (0.8%), and proliferative vitreoretinopathy (0.4%). Older age, hypertension, and postoperative hypotony had an increased risk of posterior segment complications of AVI. CONCLUSIONS: The overall incidence of posterior segment complications of AVI was 31.4%. Older age, hypertension, and postoperative hypotony were significantly associated with posterior segment complications of AVI.

Particulate Matter Exposure Aggravates IL-17-Induced Eye and Nose Inflammation in an OVA/Poly(I:C) Mouse Model.

PURPOSE: Data on the effects of direct particulate matter (PM) exposure on the eyes and the nose are limited. Here, an interleukin (IL)-17/neutrophil-dominant ovalbumin (OVA)/polyinosinic-polycytidylic acid (Poly(I:C)) mouse model was used to evaluate the effect of different-sized titanium dioxide (TiO2) particles on the eyes and the nose. We also examined whether IL-17-neutralizing antibody (IL-17Ab) treatment could reverse TiO2 effects. METHODS: The nasal cavities and conjunctival sacs of each mouse were challenged with OVA and Poly(I:C) to induce neutrophil-dominant inflammation and then exposed to micro- and nano-TiO2. Subsequently, IL-17Ab was administered to investigate the role of IL-17 and inflammatory parameters. RESULTS: Micro- and nano-TiO2 resulted in significant decreases in tear-break-up time and increases in corneal damage. Airborne micro-TiO2 also increased nasal rubbing and sneezing counts compared with the OVA/Poly(I:C). Micro-TiO2 exposure increased infiltration of neutrophils and IL-17A+ cells in the conjunctival tissues and the nasal mucosae. In addition, these increased symptoms and inflammation in the eyes and the nose by micro-TiO2 exposure were inhibited by the IL-17Ab, suggesting IL-17 dependency. CONCLUSIONS: TiO2 aggravated IL-17-induced eye and nose inflammation and the IL-17Ab alleviated inflammation in the OVA/Poly(I:C) mouse model. These results may help develop a therapeutic modality for PM exposure and provide evidence for PM-associated diseases.

Demodex Blepharitis: An Analysis of Nine Patients.

Inflammatory eyelid symptoms are common in primary care and there have been several reports on Demodex blepharitis. In the present study, we evaluate the 9 patients with Demodex blepharitis, who showed inflammation of the eyelids, dry eye, and cylindrical dandruff at the base of the eyelashes. The causative species from all patients was Demodex folliculorum of either the adult or nymph stage. Two patients had recurrent chalazion and 3 patients had keratitis. Weekly lid scrubs with 50% tee tree oil were performed for 6 weeks. After treatment, the symptoms of blepharitis and keratitis had improved in all patients. This case report provides clinical reference source for the proper treatment of ocular demodicosis.

Bilateral Trichosporon asahii keratitis after ptosis correction: A case report.

RATIONALE: Fungal keratitis (FK) is a severe vision-threatening disease that can lead to corneal perforation or endophthalmitis despite proper treatment. It is important to diagnose the disease promptly due to its indolent nature and disproportionate disease symptoms. Trichosporon asahii is reported rarely as the causative organism of FK. We report a case of highly unusual bilateral T asahii keratitis following ptosis surgery. PATIENT CONCERNS: An 86-year-old female underwent bilateral levator resection surgery for ptosis. Postoperatively, the patient complained of gradually worsening bilateral ocular pain and a decrease in visual acuity associated with a chronic non-healing epithelial defect. DIAGNOSES: Both eyes of the patient were evaluated using best-corrected visual acuity, intraocular pressure, slit-lamp examination, fundus examination, and corneal culture. Multifocal deep stromal infiltrates were found in both corneas. Cultures from both corneal ulcers revealed growth of T asahii. Optical coherence tomographic examination showed bilateral macular edema. INTERVENTIONS: The patient was treated with revisional ptosis surgery, an antifungal agent for the corneal ulcer, and intravitreal injection of steroid for macular edema. OUTCOMES: Both eyes recovered well. Her best-corrected visual acuity improved from 20/200 to 20/40 in the right eye and from 20/100 to 20/40 in the left eye. LESSONS: FK can develop in the cornea when certain risk factors are present, including recent lid surgery, chronic keratitis, and steroid eye drop use. Identification and correction of risk factors can be beneficial in the treatment of FK.

Explainable Machine Learning Model for Glaucoma Diagnosis and Its Interpretation.

The aim is to develop a machine learning prediction model for the diagnosis of glaucoma and an explanation system for a specific prediction. Clinical data of the patients based on a visual field test, a retinal nerve fiber layer optical coherence tomography (RNFL OCT) test, a general examination including an intraocular pressure (IOP) measurement, and fundus photography were provided for the feature selection process. Five selected features (variables) were used to develop a machine learning prediction model. The support vector machine, C5.0, random forest, and XGboost algorithms were tested for the prediction model. The performance of the prediction models was tested with 10-fold cross-validation. Statistical charts, such as gauge, radar, and Shapley Additive Explanations (SHAP), were used to explain the prediction case. All four models achieved similarly high diagnostic performance, with accuracy values ranging from 0.903 to 0.947. The XGboost model is the best model with an accuracy of 0.947, sensitivity of 0.941, specificity of 0.950, and AUC of 0.945. Three statistical charts were established to explain the prediction based on the characteristics of the XGboost model. Higher diagnostic performance was achieved with the XGboost model. These three statistical charts can help us understand why the machine learning model produces a specific prediction result. This may be the first attempt to apply "explainable artificial intelligence" to eye disease diagnosis.

Comparative study on the effect of hyperthermic massage and mechanical squeezing in the patients with mild and severe meibomian gland dysfunction: An interventional case series.

BACKGROUND: Meibomian glands exist beneath the palpebral conjunctiva; thus, it is invisible to the naked eye without infrared imaging. This study used meibography to group patients with meibomian gland dysfunction (MGD) and assessed the effects of hyperthermic massage and mechanical squeezing in both groups. MATERIALS AND METHODS: Patients with MGD were divided into two groups, according to the degree of meibomian gland loss: group 1, in which the sum of eyelid scores ranged from 0 to 4 (mild to moderate gland loss) and group 2, in which the sum of eyelid scores ranged from 5 to 6 (severe gland loss). Hyperthermic massage and mechanical squeezing were given to both groups once a week for 4 weeks, and only non-preservative artificial tears were allowed. Ocular surface disease index (OSDI), Schirmer's test, meibography score, tear break-up time (TBUT), ocular surface staining, expressible meibomian gland, and quality before and after treatment were compared. RESULTS: Of the 49 patients who completed the 4 weeks of treatment and the evaluation at week 5, 29 were assigned to group 1 and 20 were assigned to group 2. Meibography scores, OSDI, TBUT, and expressibility of meibum had significant differences before and after treatments in both groups. However, there was no significant difference between the changes in clinical signs between group 1 and 2 after treatment. Without grouping, all patients showed significant decreases in meibography score, OSDI, cornea staining score, and increases in TBUT and expressibility of meibum after treatment. CONCLUSIONS: Considering the results of the current study, hyperthermic massage and mechanical squeezing may be effective in patients with meibomian gland loss, regardless of the degree of severity.

Metabolomics approach to biomarkers of dry eye disease using 1H-NMR in rats.

Dry eye disease (DED) is a chronic and progressive lesion on the ocular surface and induces symptoms, such as burning sensation, itchy eyes, heavy eyes, tired eyes, dry feeling, facial flushing, and blurred vision. The present study was performed to develop DED biomarkers using metabolomics in a rat model. DED was induced by injecting scopolamine and exposing rats to a dry condition. Scopolamine (12 mg/kg/day for 7 days) was subcutaneously injected to male Sprague-Dawley rats. The rats were placed in dry condition with air-flow and dehumidifier. Tear volume and tear breakup time (TBUT) were measured, and eyes were examined through fluorescein staining to assess DED. Mucosal damage and immune reactions were also determined. Plasma and urinary endogenous metabolites were determined using 1H-NMR analysis. Compared with control tear and TBUT levels were significantly decreased in the DED group whereas corneal damage was significantly increased. The levels of interleukins (IL-6) and IL-1ß significantly elevated in the cornea and lacrimal glands in the DED group. TNF-α was numerically increased but not significantly different between groups. Pattern recognition using principal component analysis (PCA) and orthogonal projections to latent structure-discriminant analysis (OPLS-DA) of the NMR spectra in global profiling revealed different clusters between DED and control groups. Target profiling demonstrated that PCA and OPLS-DA score plots were separated between DED and controls in plasma and urine. Subsequently, 9 plasma metabolites were selected to examine different clustering between groups, and 26 urinary metabolites were also selected. Plasma metabolites showed a non-significant rising tendency in the DED group. Urinary phenylalanine, phenylacetate, pantothenate, glycine, succinate, methanol, valine, propylene glycol, histidine, threonine, lactate, and acetate were significantly different between control and DED rats. These results may contribute to understanding the metabolic regulation that is involved in DED and might be useful for potential biomarkers related to DED in rats.

Effect of 808-nm Laser Photobiomodulation Treatment in Blepharitis Rat Model.

PURPOSE: Blepharitis, simply defined as eyelid inflammation, is one of the common ocular conditions associated with discomfort and irritation. Because blepharitis causes meibomian gland dysfunction and dry eye, this study aimed to confirm the effect of photobiomodulation (PBM) on blepharitis. METHODS: A total of 20 rats were randomly assigned to 4 equal groups, including control, blepharitis, PBM, and eye drop. Blepharitis was induced in rats by injecting complete Freund's adjuvant in the eyelid margins. PBM intervention was given every 3 days after blepharitis induction. Clinical signs including tear volume, tear breakup time (TBUT), meibomian gland swelling, fluorescein, telangiectasia, and meibomian gland secretion scores were measured every week, and the rats were killed for histological analysis after 4 weeks. Immunohistochemistry was performed to compare the level of inflammatory cytokines, interleukin-1ß and tumor necrosis factor-α, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining on retina was performed to observe any retinal damage. RESULTS: Tear volume and TBUT increased with PBM intervention, and with improved eyelid swelling, corneal staining, telangiectasia, and meibomian gland secretion scores increased. Hematoxylin and eosin staining showed no structural abnormalities of meibomian gland caused by blepharitis induction. Immunohistochemistry revealed that the levels of inflammatory cytokines interleukin-1ß and tumor necrosis factor-α were lowered with PBM treatment in both eyelid and conjunctiva. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining showed no retinal damage. CONCLUSIONS: Laser PBM at 808 nm was effective in alleviating ocular signs and controlling inflammation in blepharitis rat model. The in vivo results suggest that PBM has the potential to be used in treating blepharitis patients.

Outcome of phacoemulsification in patients with open-angle glaucoma after selective laser trabeculoplasty.

PURPOSE: To investigate the outcome of phacoemulsification in selective laser trabeculoplasty (SLT)-treated eyes. METHODS: This retrospective study included patients who had open angle glaucoma (OAG) with previous SLT who underwent phacoemulsification. We evaluated intraocular pressure (IOP), length of glaucoma control without treatment, and antiglaucoma medication or surgery. SLT-treated eyes that did not receive phacoemulsification were retrospectively chosen as a control. We investigated factors related to outcome of phacoemulsification by multivariate analysis. RESULTS: 42 eyes with previous SLT that underwent phacoemulsification and 40 controls were retrospectively evaluated. Phacoemulsification was performed 52 ± 15 months after SLT. After a mean follow-up of 74 ± 21 months, mean IOP was significantly decreased in the phaco group by 2.2 ± 2.7 mmHg (p < 0.001). In the SLT group, mean IOP was decreased by 0.8 ± 2.8 mmHg (p < 0.001). 9 eyes (16.7%) in the phaco group and 11 eyes (19.0%) of the SLT group needed topical treatment, and no eye needed glaucoma surgery in both groups. The factor related to success was higher baseline IOP (p = 0.002). CONCLUSION: Prior SLT didn't negatively influence phacoemulsification in patients with OAG. Phacoemulsification lowered IOP effectively and safely in OAG patients who were treated with SLT.

Clinical efficacy of eyelid hygiene in blepharitis and meibomian gland dysfunction after cataract surgery: a randomized controlled pilot trial.

The purpose of this randomized clinical trial is to evaluate the effect of eyelid hygiene on subjective symptoms, anterior blepharitis, and meibomian gland dysfunction (MGD) after cataract surgery. Subjects with obstructive MGD who underwent cataract surgery were randomly divided into two groups. In the eyelid hygiene group, eyelid hygiene was performed twice a day for 10 days from 3 days before to 1 week after cataract surgery. The control group did not perform eyelid hygiene. A subjective symptom questionnaire of SPEED, anterior blepharitis grade, and meibum quality and quantity was evaluated at baseline and at postoperative 1 and 4 weeks. The eyelid hygiene group (n = 36) showed decreased SPEED score after cataract surgery and the control group (n = 33) did not. Anterior blepharitis grade was worse 1 week after surgery in the control group but not in the eyelid hygiene group. The control group had significantly decreased meibum quality and quantity in both the upper and lower eyelids after cataract surgery, but the eyelid hygiene group did not. Eyelid hygiene before/after cataract surgery improved postoperative subjective symptoms and prevented postoperative exacerbation of anterior blepharitis and MGD. Thus, perioperative eyelid hygiene is recommended for patients with obstructive MGD who undergo cataract surgery.

Sestrin2 inhibits YAP activation and negatively regulates corneal epithelial cell proliferation.

Corneal wound healing is essential for the maintenance of corneal integrity and transparency and involves a series of physiological processes that depend on the proliferation of epithelial cells. However, the molecular mechanisms that control corneal epithelial cell proliferation are poorly understood. Here, we show that Sestrin2, a stress-inducible protein, is downregulated in the corneal epithelium during wound healing and that the proliferation of epithelial basal cells is enhanced in Sestrin2-deficient mice. We also show that YAP, a major downstream effector of the Hippo signaling pathway, regulates cell proliferation during corneal epithelial wound repair and that Sestrin2 suppresses its activity. Moreover, increased levels of reactive oxygen species in the Sestrin2-deficient corneal epithelium promote the nuclear localization and dephosphorylation of YAP, activating it to enhance the proliferation of corneal epithelial cells. These results reveal that Sestrin2 is a negative regulator of YAP, which regulates the proliferative capacity of basal epithelial cells, and may serve as a potential therapeutic target for corneal epithelial damage.

Distribution and Characteristics of Meibomian Gland Dysfunction Subtypes: A Multicenter Study in South Korea.

PURPOSE: We sought to evaluate the distribution and characteristics of meibomian gland dysfunction (MGD) and the treatment patterns for symptomatic MGD patients in South Korea. METHODS: One hundred ninety-six right eyes of 196 MGD patients were enrolled. For each patient, meibum expressibility in the central eight glands in both the upper and lower eyelids was examined. Each upper and lower eyelid was separately classified into one of the following three subtypes: nonobvious obstructive (low-delivery without lid margin abnormality), obvious obstructive (low-delivery with lid margin abnormality), and hypersecretory (high-delivery with lid margin abnormality). All treatment plans were also recorded. RESULTS: The mean number of expressible glands of the central eight glands in the upper eyelids (3.9 ± 2.6) was significantly higher than that in the lower eyelids (2.2 ± 2.4, p < 0.001). Obvious obstructive MGD was the most common subtype, followed by the hypersecretory and nonobvious obstructive subtypes in both the upper and lower eyelids. Of the 196 subjects, 38 (19.4%) had upper and lower eyelids that were assigned to different categories. Eyelid hygiene was the most prescribed treatment (74.5%), followed by lubricant eye drop usage (71.5%). Physicians tended to determine treatment plans based on the subtype of the upper eyelid rather than that of the lower eyelid. CONCLUSIONS: The majority of subjects were classified as having the obvious obstructive subtype of MGD, and 19.4% had upper and lower eyelids that were different subtypes. Eyelid hygiene was the most prescribed treatment for MGD patients, and treatment patterns were mostly determined based on the subtype of the upper eyelids.

Comparison of peripapillary and macular choroidal thickness and ganglion cell complex thickness in glaucomatous and healthy eyes.

AIM: To assess choroidal thickness (CT) and its association with ganglion cell-inner plexiform layer thickness (GCIPLT) and retinal nerve fiber layer thickness (RNFLT) in open angle glaucoma (OAG) comparing with preperimetric glaucoma (PPG) and normal eyes. METHODS: Totally 55 eyes of OAG, 40 eyes of PPG, and 40 eyes of age-matched normal eyes were studied. Peripapillary CT (PCT), macular CT (MCT), RNFLT, and GCIPLT were evaluated. Relationship between the CT with RNFLT and GCIPLT were studied. The correlation between CT and confounding variables as gender, age, intraocular pressure, and visual field mean deviation were analyzed. RESULTS: Mean PCT were 113.6±39.1 µm in OAG, 116.3±42.7 µm in PPG, and 148.9±41.7 µm in normal eyes. PCT and MCT was thinner in OAG compared to healthy eyes. There was a significant correlation for PCT and mean RNFLT in 1, 2, 6, and 7 clock hours of OAG eyes. The difference in PCT remained after adjusting for axial length, age, and disc area (P=0.003). No significant correlation was shown between MCT and mean GCIPLT in all eyes. CONCLUSION: PCT is thinner in OAG and PPG compared with healthy eyes. The correlation of RNFLT and PCT found in OAG and PPG is not revealed in normal eyes.

Choroidal vascular index in patients with open angle glaucoma and preperimetric glaucoma.

PURPOSE: To evaluate choroidal structural changes in glaucoma using choroidal vascularity index (CVI) compared to healthy subjects. METHODS: This retrospective study included 56 patients with open angle glaucoma (OAG), 50 patients with preperimetric glaucoma (PPG) and 50 age-matched healthy eyes. Choroidal images were binarized into luminal area (LA) and stromal area. CVI was defined as the ratio of LA to total circumscribed choroid area (TCA). Mean choroidal thickness (CT) and mean CVI between glaucoma patients and healthy subjects were compared. RESULTS: OAG and PPG eyes showed smaller LA (0.45 ± 0.13 ㎟ vs. 0.47 ± 0.11 ㎟, p = 0.04). In multivariate regression analysis, CVI of both OAG (64.34±0.19%, p = 0.001) and PPG (65.37±0.15%, p = 0.001) were significantly lower than healthy eyes (68.81±0.14%). CONCLUSION: Eyes with glaucoma demonstrated reduced CVI compared with healthy eyes. CVI may be a potential noninvasive tool for studying vascular dysfunction in glaucoma.

Author Correction: The use of microfluidic spinning fiber as an ophthalmology suture showing the good anastomotic strength control.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.