Ocular Surface Disorders Research Articles

Assessment of Dry Eye Syndrome among Computer Programmers in Computer Training Institutes in Benin City

Purpose: The purpose of this study was to evaluate dry eye syndrome among computer programmers in computer training institutes in Benin City.Methods: This cross-sectional study was carried out using 250 participants of 18 years and above who were computer instructors and students of various computer training institutes in Benin City. Sociodemographic data and relevant ocular history were obtained from the participants. External and Internal examinations of the eyes were carried out to check for the presence of any ocular abnormalities. Dryeye disease was assessed subjectively with the Ocular Surface Disease Index (OSDI) questionnaire and objectively by performing Schirmer’s test and Tear Break-up Time (TBUT). Participants with an OSDI score of ≥35 and who had < 10mm to Schirmer’s I test or < 10secs in Tear break-up Time (TBUT) test were considered to have dry eye.Results: The mean age of the participants was 25.32 ± 7.38 years and 68% were males. The prevalence of dry eye among the computer programmers was found to be 30.8%. Mean TBUT and Mean Schirmer’s Test value for those with dry eye was 10.21s±3.44s and 12.46 ± 7.27mm respectively. This study showed that age (p=0.213), gender (p=0.243) and duration of time spent on computer display units (p=0.124) were not statistically significant determinants of dry eye among the computer programmers.Conclusion: Computer programmers are predisposed to developing dry eye diseases. It is therefore imperative for them to go for regular eye examination to prevent ocular surface disorders and therefore maintain comfortable vision.
 Keywords: Dry Eye, Schirmer Test, Tear Break-up Time, Ocular Surface Disease Index, Computer Programmer.

Surgical Application of Human Amniotic Membrane and Amnion-Chorion Membrane in the Oral Cavity and Efficacy Evaluation: Corollary With Ophthalmological and Wound Healing Experiences.

Due to its intrinsic properties, there has been growing interest in human amniotic membrane (hAM) in recent years particularly for the treatment of ocular surface disorders and for wound healing. Herein, we investigate the potential use of hAM and amnion-chorion membrane (ACM) in oral surgery. Based on our analysis of the literature, it appears that their applications are very poorly defined. There are two options: implantation or use as a cover material graft. The oral cavity is submitted to various mechanical and biological stimulations that impair membrane stability and maintenance. Thus, some devices have been combined with the graft to secure its positioning and protect it in this location. This current opinion paper addresses in detail suitable procedures for hAM and ACM utilization in soft and hard tissue reconstruction in the oral cavity. We address their implantation and/or use as a covering, storage format, application side, size and number, multilayer use or folding, suture or use of additional protective covers, re-application and resorption/fate. We gathered evidence on pre- and post-surgical care and evaluation tools. Finally, we integrated ophthalmological and wound healing practices into the collected information. This review aims to help practitioners and researchers better understand the application of hAM and ACM in the oral cavity, a place less easily accessible than ocular or cutaneous surfaces. Additionally, it could be a useful reference in the generation of new ideas for the development of innovative protective covering, suturing or handling devices in this specific indication. Finally, this overview could be considered as a position paper to guide investigators to fulfill all the identified criteria in the future.

The role of environment in the pathogenesis of keratoconus

This study was conducted to demonstrate the importance of the environment in keratoconus (KC) genesis. Genetic-related connective tissue disorders demonstrate the inconsistency of theories regarding KC pathogenesis since no corneal steepening was observed in the majority of these patients. Despite recent advances and decades of research into the genetics of KC, the identification of disease-causing KC genes has been frustrating. Variants found based on genome-wide and next-generation sequencing only seem to account for a small number of cases or play a limited role in KC pathogenesis. The literature shows that mechanical manipulation may be the common underlying factor or the indispensable act precipitating the cascade of events leading to permanent corneal deformation. Hence, ophthalmologists have the opportunity to increase patient awareness about eye manipulation repercussions and treatment for ocular surface disorders. http://links.lww.com/COOP/A42.

Age-related changes in ocular mucosal tolerance: Lessons learned from gut and respiratory tract immunity.

The ocular surface is the part of the visual system directly exposed to the environment, and it comprises the cornea, the first refractive tissue layer and its surrounding structures. The ocular surface has evolved to keep the cornea smooth and wet, a prerequisite for proper sight, and also protected. To this aim, the ocular surface is a bona fide mucosal niche with an immune system capable of fighting against dangerous pathogens. However, due to the potential harmful effects of uncontrolled inflammation, the ocular surface has several mechanisms to keep the immune response in check. Specifically, the ocular surface is maintained inflammation-free and functional by a particular form of peripheral tolerance known as mucosal tolerance, markedly different from the immune privilege of intraocular structures. Remarkably, conjunctival tolerance is akin to the oral and respiratory tolerance mechanisms found in the gut and airways, respectively. And also similarly, this form of immunoregulation in the eye is affected by ageing just as it is in the digestive and respiratory tracts. With ageing comes an increased prevalence of immune-based ocular surface disorders, which could be related to an age-related impairment of conjunctival tolerance. The purpose of this review was to summarize the present knowledge of ocular mucosal tolerance and how it is affected by the ageing process in the light of the current literature on mucosal immunoregulation of the gut and airways.

Effects on the Ocular Surface from Reading on Different Smartphone Screens: A Prospective Randomized Controlled Study.

The purpose of this study was to investigate the influence of smartphone reading on the ocular surface and to compare the various effects of different screens and light conditions on the ocular surface. One hundred nineteen volunteers were randomly divided into: light + organic light‐emitting diode (OLED), light + electronic ink (eINK), dark + OLED, and dark + eINK. Ocular surface examinations, including noninvasive break‐up time (NIBUT), noninvasive keratograph tear meniscus height (NIKTMH), ocular redness, fluorescein break‐up time (FBUT), corneal fluorescein staining, meibomian gland assessment, Schirmer I Test, and blinking frequency, were performed before and after a reading task. Symptoms were evaluated using the Ocular Surface Disease Index (OSDI) and Computer Vision Syndrome Questionnaire (CVS‐Q). NIBUT and FBUT were decreased statistically significantly after participants read on an OLED screen for 2 hours compared with the baseline in light and dark environments, whereas no statistically significant decrease was observed on an eINK screen. NIKTMH was statistically significantly decreased after reading on an OLED screen in light and dark settings, and the eINK screen had a lesser effect on NIKTMH. An obvious increase in the ocular redness, OSDI and CVS‐Q scores was observed after reading on an OLED screen, whereas the eINK screen had a lesser effect on these indicators. Blink rate increased gradually in OLED subgroups during the reading task, whereas no statistically significant difference was observed in the eINK subgroups. Our research suggested that reading on an OLED screen can cause ocular surface disorder and obvious subjective discomfort, whereas reading on an eINK screen can minimize ocular surface disorder in both dark and light environments.

Encounters and medication use for ocular surface disorders among patients treated with dupilumab: A cohort study

BackgroundAlthough dupilumab has been associated with the development of conjunctivitis, little is known about other ocular surface disorders such as dry eye and how these side effects are managed.ObjectiveTo evaluate the incidence and management of ocular surface disorders, including dry eye and conjunctivitis, among patients treated with dupilumab.MethodsUsing US claims data, we evaluated the incidence of encounters for ocular surface disorders among patients treated with dupilumab. Secondary outcomes included ophthalmic medication use. A propensity score matched, active-comparator, new-user cohort design was used to compare the incidence of ocular surface disorders between those starting dupilumab versus methotrexate.ResultsAmong those with a history of atopic dermatitis, encounters for ocular surface disorders were more common in the 6 months after starting dupilumab than in the 6 months prior (11.7% versus 8.7%, P < .001); 59.7% of those with a new ocular surface disorder diagnosis filled a prescription for an ophthalmic medication. The incidence of ocular surface disorders was higher among those treated with dupilumab than that in those treated with methotrexate (odds ratio 1.64; 95% confidence interval 1.17-2.30).LimitationsObservational design.ConclusionsDupilumab use for atopic dermatitis was associated with an increased risk of ocular surface disorders. Most patients who developed an ocular surface disorder received a prescription for an ophthalmic medication.

Ocular Manifestations and Neuropathy in Type 2 Diabetes Patients With Charcot Arthropathy.

ObjectiveDiabetes can affect the eye in many ways beyond retinopathy. This study sought to evaluate ocular disease and determine any associations with peripheral neuropathy (PN) or cardiac autonomic neuropathy (CAN) in type 2 diabetes (T2D) and Charcot arthropathy (CA) patients.DesignA total of 60 participants were included, 16 of whom were individuals with T2D/CA, 21 of whom were individuals with T2D who did not have CA, and 23 of whom were healthy controls. Ocular surface evaluations were performed, and cases of dry eye disease (DED) were determined using the Ocular Surface Disease Index (OSDI) questionnaire, ocular surface staining, Schirmer test, and Oculus Keratograph 5M exams. All variables were used to classify DED and ocular surface disorders such as aqueous deficiency, lipid deficiency, inflammation, and ocular surface damage. Pupillary and retinal nerve fiber measurements were added to the protocol in order to broaden the scope of the neurosensory ocular evaluation. PN and CAN were ascertained by clinical examinations involving the Neuropathy Disability Score (for PN) and Ewing’s battery (for CAN).ResultsMost ocular variables evaluated herein differed significantly between T2D patients and controls. When the controls were respectively compared to patients with T2D and to patients with both T2D and CA, they differed substantially in terms of visual acuity (0.92 ± 0.11, 0.73 ± 0.27, and 0.47 ± 0.26, p=0.001), retinal nerve fiber layer thickness (96.83 ± 6.91, 89.25 ± 10.44, and 80.37 ± 11.67 µm, p=0.03), pupillometry results (4.10 ± 0.61, 3.48 ± 0.88, and 2.75 ± 0.81 mm, p=0.0001), and dry eye symptoms (9.19 ± 11.71, 19.83 ± 19.08, and 24.82 ± 24.40, p=0.03). DED and ocular surface damage also differed between individuals with and without CA, and were associated with PN and CAN.ConclusionCA was found to be significantly associated with the severity of ocular findings. DED in cases of CA was also associated with PN and CAN. These findings suggest that intrinsic and complex neurosensory impairment in the eyes, peripheral sensory nerves, and the autonomic nervous system are somehow connected. Thus, a thorough ocular evaluation may be useful to highlight neurological complications and the impact of diabetes on ocular and systemic functions and structures.

A single cell atlas of human cornea that defines its development, limbal progenitor cells and their interactions with the immune cells

PurposeSingle cell (sc) analyses of key embryonic, fetal and adult stages were performed to generate a comprehensive single cell atlas of all the corneal and adjacent conjunctival cell types from development to adulthood. MethodsFour human adult and seventeen embryonic and fetal corneas from 10 to 21 post conception week (PCW) specimens were dissociated to single cells and subjected to scRNA- and/or ATAC-Seq using the 10x Genomics platform. These were embedded using Uniform Manifold Approximation and Projection (UMAP) and clustered using Seurat graph-based clustering. Cluster identification was performed based on marker gene expression, bioinformatic data mining and immunofluorescence (IF) analysis. RNA interference, IF, colony forming efficiency and clonal assays were performed on cultured limbal epithelial cells (LECs). ResultsscRNA-Seq analysis of 21,343 cells from four adult human corneas and adjacent conjunctivas revealed the presence of 21 cell clusters, representing the progenitor and differentiated cells in all layers of cornea and conjunctiva as well as immune cells, melanocytes, fibroblasts, and blood/lymphatic vessels. A small cell cluster with high expression of limbal progenitor cell (LPC) markers was identified and shown via pseudotime analysis to give rise to five other cell types representing all the subtypes of differentiated limbal and corneal epithelial cells. A novel putative LPCs surface marker, GPHA2, expressed on the surface of 0.41% ± 0.21 of the cultured LECs, was identified, based on predominant expression in the limbal crypts of adult and developing cornea and RNAi validation in cultured LECs. Combining scRNA- and ATAC-Seq analyses, we identified multiple upstream regulators for LPCs and demonstrated a close interaction between the immune cells and limbal progenitor cells. RNA-Seq analysis indicated the loss of GPHA2 expression and acquisition of proliferative limbal basal epithelial cell markers during ex vivo LEC expansion, independently of the culture method used. Extending the single cell analyses to keratoconus, we were able to reveal activation of collagenase in the corneal stroma and a reduced pool of limbal suprabasal cells as two key changes underlying the disease phenotype. Single cell RNA-Seq of 89,897 cells obtained from embryonic and fetal cornea indicated that during development, the conjunctival epithelium is the first to be specified from the ocular surface epithelium, followed by the corneal epithelium and the establishment of LPCs, which predate the formation of limbal niche by a few weeks. ConclusionsOur scRNA-and ATAC-Seq data of developing and adult cornea in steady state and disease conditions provide a unique resource for defining genes/pathways that can lead to improvement in ex vivo LPCs expansion, stem cell differentiation methods and better understanding and treatment of ocular surface disorders.

The "Quarantine Dry Eye": The Lockdown for Coronavirus Disease 2019 and Its Implications for Ocular Surface Health.

The pandemic of coronavirus disease 2019 (COVID-19) has led many countries of the world to impose a series of containment measures such as lockdowns (mass quarantines), curfews or similar restrictions (eg, stay-at-home orders, or shelter-in-place orders). All these restrictions were established in order to limit spread of COVID-19. Thus, approximately 3.9 billion people worldwide were under lockdown by early April 2020. During this time (home confinement), some solutions have been proposed by experts to improve work and school productivity, including smart working and online school lessons. However, many of the restrictive measures are likely to act as predisposing factors for dry eye disease (DED), directly or related to sick building syndrome (SBS). Herein, we discuss the implications of quarantine measures on eye health, in particular on DED associated with SBS, and introduce some potential preventive strategies for lockdown-related ocular surface disorders. Several risk factors are implicated in their pathogenesis, including environmental changes (eg, air quality) and modifications in personal behaviors (eg, the abuse of digital devices, malnutrition, and sleep/psychiatric disorders). Considering a number of predisposing factors for DED, it is possible to state that patients under lockdown are at risk of ocular surface alterations. Accordingly, the COVID-19 pandemic era is expected to determine an increase in dry eye patients all around the world (a new phenomenon that we propose to name the “quarantine dry eye”) in the event that the restrictive measures will be recursively extended over time.

Ocular surface disease in psoriatic patients in a developing country.

To evaluate ocular surface changes among patients with psoriasis in Malaysia, a developing country in Southeast Asia. An interdisciplinary case-control study (60 psoriasis patients and 40 control subjects) to look at the differences in ocular surface manifestations between patients with psoriasis and a group of age-, gender- and ethnicity-matched healthy controls. One hundred and twenty eyes of 60 patients with psoriasis and 80 eyes of 40 healthy controls without psoriasis were included in the study. Mild-to-moderate psoriasis was found in 42 patients (70%), while 18 patients (30%) had severe psoriasis. Psoriatic arthritis was found in 19 patients (32%). Of the 60 psoriatic patients, the prevalence of ocular involvement was 65% (39/60), in which 32% (19/60) had dry eyes, 27% (16/60) had lid margin abnormalities, 33% (20/60) had cataract, and one had history of anterior uveitis. Compared to controls, ocular surface of psoriatic patients showed more eyelid margin abnormalities, higher meibomian gland loss and lower tear filmbreak-up time. The estimated odds ratio for dry eyes in the psoriasis group was 2.2 (95% CI: 0.8-6.9). Ocular surface disorders encompassing eyelid margin abnormalities, meibomian gland loss and tear dysfunction occur at an earlier and higher rate among psoriatic patients.

Anterior-segment optical coherence tomography for the detection and therapeutic monitoring of corneal disorders

Background: Over recent years a revolutionary trend happened on imaging technologies to diagnose and monitor treatment of a varied group of ophthalmic pathologies. Recent reports have analyzed the microstructural changes of various ocular surface and corneal disorders, particularly ocular surface squamous neoplasia (OSSN) and keratoconus using anterior-segment optical coherence tomography (AS-OCT). Aim of this short communication is to elaborate on clinical applications AS-OCT for the detection and therapeutic monitoring of corneal disorders.&#x0D; Methods: We performed an English literature search without a time limit and intending to identify articles related to the AS-OCT applications in the detection and therapeutic monitoring of corneal disorders. The most relevant articles were selected. practical points of selected papers and advantages and disadvantages of AS-OCT were retrieved from them and summarized.&#x0D; Results:.Many records reported the AS-OCT applications for diagnosing many ocular surface disorders, the microstructural changes of different inflammatory, infectious, degenerative, and dystrophic corneal disorders. Its applications in identifying disease activity and therapeutic monitoring of various corneal pathologies, including stromal edema associated with angle-closure glaucoma, Fuchs endothelial dystrophy, infectious keratitis, and bullous keratopathy, are promising. The percentage of diagnostic sensitivity, specificity, and accuracy of artificial intelligence methodologies applied to AS-OCT imaging analysis today has reached 94% to 100%. Moreover, AS-OCT is very useful for analyzing the extension of scar and leukoma depth for surgical planning of partial or total corneal transplantation.&#x0D; Conclusions: There is a clear prospect for expanding application of corneal OCT imaging technology, a rapid, non-invasive, and now a promising lower-cost device, which is becoming an in-office standard-of-care tool for the assessment of different corneal and ocular surface pathologies.&#x0D; KEYWORDS&#x0D; anterior-segment optical coherence tomography, AS-OCT, ocular surface disorders, corneal disorders, ocular surface squamous neoplasia, OSSN, keratoconus

Ocular surface disorders in dogs and cats submitted to dissociative anesthesia in elective orchiectomy procedure

The present study aims to verify whether dogs and cats submitted to dissociative anesthesia for elective orchiectomy may present alterations in the tear production and consequent lesions on the ocular surface. For this purpose, 40 animals, 22 cats and 18 dogs, underwent an ophthalmic semiotechnique composed of the evaluation of anterior and posterior chambers, fundscopy, Schirmer's tear test (TLS) and fluorescein test. Subsequently, they underwent dissociative anesthesia, associating ketamine with diazepam or midazolam. Immediately at the end of the procedure, the fluorescein and TLS test was repeated. After 24 hours, a new ophthalmic evaluation was performed to compare the results obtained. There were no ophthalmic changes. With the use of diazepam, TLS remained within the normal range with a median of 19 mm / min, with a mean and standard deviation of 19.27 ± 3.01 mm / min for dogs and a median of 18 mm / min, with a mean and standard deviation of 19.05 ± 2.81 mm / min for cats. When using midazolam, the TLS of the dogs had a median of 19 mm / min, with a mean and standard deviation of 18.84 ± 2.69 mm / min and of the cats, they had a median of 18 mm / min with a mean and standard deviation of 18.37 ± 2.32 mm / min. The results found suggest that the use of dissociative anesthesia for short procedures does not significantly alter the tear production, nor does it cause eye injuries.

Association Between Air Pollution and the Risk of Uveitis: A Nationwide, Population-Based Cohort Study.

Previous studies have revealed an association between ocular surface disorders and air pollution, few studies have focused on the risk of uveitis. We aimed to investigate whether air pollution increases the risk of uveitis. We used the Taiwan Longitudinal Health Insurance Database (LHID) and the Taiwan Air Quality Monitoring Database (TAQMD) to conduct a retrospective cohort study. Air pollutant concentrations, including those of carbon dioxide (CO2), were grouped into four levels according to quartiles. The outcome was the incidence of uveitis, as defined in the International Classification of Diseases, Ninth Revision. We used univariable and multivariable Cox proportional hazard regression models to calculate the adjusted hazard ratios (aHRs) and determine the potential risk factors of uveitis. Overall, 175,489 subjects were linked to their nearby air quality monitoring stations. We found that for carbon monoxide, the aHRs of uveitis risk for the Q3 and Q4 levels were 1.41 (95% confidence interval (CI) = 1.23–1.61) and 2.19 (95% CI = 1.93–2.47), respectively, in comparison with those for the Q1 level. For nitric oxide, the aHRs for the Q3 and Q4 levels were 1.46 (95% CI = 1.27–1.67) and 2.05 (95% CI = 1.81–2.32), respectively. For nitrogen oxide (NOx), the aHRs for the Q2, Q3, and Q4 levels were 1.27 (95% CI = 1.11–1.44), 1.34 (95% CI = 1.16–1.53), and 1.85 (95% CI = 1.63–2.09), respectively. For total hydrocarbon (THC), the aHRs for the Q2, Q3, and Q4 levels were 1.42 (95% CI = 1.15–1.75), 3.80 (95% CI = 3.16–4.57), and 5.02 (95% CI = 4.19–6.02), respectively. For methane (CH4), the aHRs for the Q3 and Q4 levels were 1.94 (95% CI = 1.60–2.34) and 7.14 (95% CI = 6.01–8.48), respectively. In conclusion, air pollution was significantly associated with incidental uveitis, especially at high THC and CH4 levels. Furthermore, the uveitis risk appeared to increase with increasing NOx and THC levels.

English

BACKGROUND Due to the impaired ocular defence mechanisms, patients in the intensive care unit are more prone for ocular surface disorders. This creates the need for identifying the causal factors and educating the health care staff working in (intensive care unit) ICU, regarding ocular surface disorders. The prevalence of ocular surface disorders in ICU patients is about 60 %.1 We wanted to study the proportion and causative factors of ocular surface disorders in intensive care unit patients. METHODS A cross sectional study was conducted among 100 patients admitted in intensive care unit of S.V.R.R.G.G. Hospital, Tirupathi, for a duration of one year. A detailed history, clinical examination, fluorescein staining, Schirmer’s test and conjunctival cultures was done. RESULTS Out of 100 patients, 50 patients were on ventilator support and 50 patients were without ventilator support in ICU. Overall prevalence of superficial punctate keratitis was 78 %, lagophthalmos 20 %, dry eyes 88 %, microbial keratitis 17 % in patients. The prevalence of ocular surface disorders was more in ventilator supported patients. CONCLUSIONS Ocular examination should be a part of routine examination in an intensive care unit setting, because the risk of microbial keratitis can be reduced by preventing exposure keratopathy with the help of meticulous eye care. KEYWORDS Ocular Surface Disorders, Intensive Care Unit, Ventilator Support, Microbial Keratitis, Eye Care

Clinical profile, ocular morbidity and visual loss in psoriasis: Experience in a multispeciality hospital

To analyse various ocular abnormalities and visual morbidity in patients with psoriasis and to detect ocular complications following psoriasis treatment. A prospective observational study was conducted among 120 psoriasis patients. All patients underwent slit lamp examination, indirect ophthalmoscopy, Schirmer’s test, Tear breakup time and Rose Bengal staining and ancillary investigations when required. Among 120 patients, the prevalence of ocular manifestation was 57%, of whom 22% were symptomatic. Ocular features were most common in scalp psoriasis and pustular psoriasis. Disease duration was not found to have any impact on the severity of ocular manifestation. The most common ophthalmic feature was ocular surface disorder (46%), followed by cataract (30%), meibomitis (17%) and blepharitis in 16%. Correlation between tests was calculated using kappa coefficient and statistical significance was found in the pattern of conjunctival staining with a p value of 0.02. Out of 9 patients with psoriatic arthritis, 3% showed signs of chronic uveitis. Steroid induced glaucoma was seen in 27% and ocular hypertension in 21%. Corticosteroid used in systemic management frequently caused visual morbidity. Ocular signs and symptoms in psoriasis may be subtle and overlooked, hence complete ophthalmic examination is recommended for early detection of ocular abnormalities. Early treatment for dry eye is important to prevent irreversible ocular surface changes. Regular monitoring prevents steroid induced cataract and steroid induced glaucoma. As multisystem involvement is seen in psoriasis, a multidisciplinary approach reduces ocular morbidity.

Long-term outcomes of Boston keratoprosthesis type I: the Chinese People’s Liberation Army General Hospital experience

PurposeTo report the long-term outcomes of Boston keratoprosthesis type I (B-KPro type I) implantation in the management of severe ocular surface disorders.MethodsRetrospective case series. Patients who underwent B-KPro type I...

Dexmedetomidine and Tear Production: Evaluation in Dogs as Spontaneous Model for Ocular Surface Disorders.

Simple SummaryThe general anesthesia or sedation reduces both the tear production and the stability of tear film that protect corneal surface, predisposing itself to the exposure keratopathy. The aim of the present study was to evaluate the effects of intramuscular dexmedetomidine (DEX) on canine tear production, measured by standardized Schirmer Tear Test 1 (STT-1) strips, for the 8 h following sedation, in dogs. A significant effect of time on canine tear production was found, highlighting that dexmedetomidine sedative protocol significantly affects tear production in dogs. It is recommended to treat the canine eyes with tear substitutes to protect ocular surface health and the welfare of the dogs. The ocular lubrication should be performed during and up to 12 h after sedation. The present report could provide preliminary information to better understand the effect of DEX on the tear film dynamics. Tear film provides lubrication and protection to the ocular surface. The sedation reduces tear production, often leading to perioperative exposure keratopathy. The aim of the present study was to report the effects of intramuscular dexmedetomidine on canine tear production, measured by STT-1, for an experimental period of 8 h after sedation. Ten dogs who underwent sedation for routine radiologic assessment were recruited for the study. In all animals, tear production in right and left eyes was measured 15 min before sedation (T0: basal values) and 20 min (T20), 1 h (T1), 2 h (T2), 4 h (T4) and 8 h (T8) after drug administration. Analysis of variance and post hoc Bonferroni test (p < 0.05) were performed. A significant effect of time on canine tear production was found. The tear production returned to basal values at T8. So, it is recommended to treat the canine eyes with tear substitutes during and up to 12 h after sedation.

Limbal Stem Cells on Bacterial Nanocellulose Carriers for Ocular Surface Regeneration.

Limbal stem cells (LSCs) are already used in cell-based treatments for ocular surface disorders. Clinical translation of LSCs-based therapies critically depends on the successful delivery, survival, and retention of these therapeutic cells to the desired region. Such a major bottleneck could be overcome by using an appropriate carrier to provide anchoring sites and structural support to LSC culture and transplantation. Bacterial nanocellulose (BNC) is an appealing, yet unexplored, candidate for this application because of its biocompatibility, animal-free origin and mechanical stability. Here, BNC as a vehicle for human embryonic stem cells-derived LSC (hESC-LSC) are investigated. To enhance cell-biomaterial interactions, a plasma activation followed by a Collagen IV and Laminin coating of the BNC substrates is implemented. This surface functionalization with human extracellular matrix proteins greatly improved the attachment and survival of hESC-LSC without compromising the flexible, robust and semi-transparent nature of the BNC. The surface characteristics of the BNC substrates are described and a preliminary ex vivo test in simulated transplantation scenarios is provided. Importantly, it is shown that hESC-LSC retain their self-renewal and stemness characteristics up to 21 days on BNC substrates. These results open the door for future research on hESC-LSC/BNC constructs to treat severe ocular surface pathologies.

Nano-Scale Modifications of Amniotic Membrane Induced by UV and Antibiotic Treatment: Histological, AFM and FTIR Spectroscopy Evidence.

The efficiency of amniotic membrane (AM) transplantation in different types of ocular surface disorders is due to its outstanding properties such as antifibrotic, antibacterial, anti-inflammatory and antiangiogenic, working as a versatile scaffold to promote corneal tissue epithelialization. A proper preparation, preservation and clinical application are crucial for the best outcomes in the treatment of different severe ocular disorders, taking into account its fragility. In this context, by combining high-sensitivity tools such as atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy with histological and immunohistochemical examination, we aimed to investigate the ultrastructural modifications of the amniotic membrane (AM) upon UV exposure and/or antibiotic treatment, with relevance for clinical applications in ocular surface surgery. From the morphological point of view, we noticed a loss of cuboidal cells in the basal membrane, accompanied by the splitting of collagen fibers upon UV and/or gentamicin treatment, while structural alteration of proteins was evidenced by the FTIR quantitative analysis of the secondary structure. A decrease in α-helix and β-sheet content, accompanied by increased content in less ordered structures (turns, random and side chains), was noticed after all the treatments. At the nano-scale, AFM details showed modifications of collagen fibrils in terms of their thickness and network compaction upon gentamicin and/or UV treatment. The enzymatic digestion assay demonstrated that UV exposure significantly reduces the degradation rate of the AM, while gentamicin treatment promotes an accelerated enzymatic digestion upon UV exposure. In order to highlight the clinical impact of the research, a clinical case is presented showing the relevance of amniotic membrane transplantation in pterygium surgery.

Formulation Considerations for the Management of Dry Eye Disease.

Dry eye disease (DED) is one of the most common ocular surface disorders characterised by a deficiency in quality and/or quantity of the tear fluid. Due to its multifactorial nature involving several inter-related underlying pathologies, it can rapidly accelerate to become a chronic refractory condition. Therefore, several therapeutic interventions are often simultaneously recommended to manage DED efficiently. Typically, artificial tear supplements are the first line of treatment, followed by topical application of medicated eyedrops. However, the bioavailability of topical eyedrops is generally low as the well-developed protective mechanisms of the eye ensure their rapid clearance from the precorneal space, thus limiting ocular penetration of the incorporated drug. Moreover, excipients commonly used in eyedrops can potentially exhibit ocular toxicity and further exacerbate the signs and symptoms of DED. Therefore, formulation development of topical eyedrops is rather challenging. This review highlights the challenges typically faced in eyedrop development, in particular, those intended for the management of DED. Firstly, various artificial tear supplements currently on the market, their mechanisms of action, as well as their application, are discussed. Furthermore, formulation strategies generally used to enhance ocular drug delivery, their advantages and limitations, as well as their application in commercially available DED eyedrops are described.