The pathology of dry eye: the interaction between the ocular surface and lacrimal glands

Is the main lacrimal gland indispensable? Contributions of the corneal and conjunctival epithelia

The ocular surface system is responsible for ensuring that the precorneal tear film is sufficient in both quality and quantity to preserve optimal vision. Tear secretion is a complex, multifactorial process, and dysfunction of any component of the ocular surface system can result in tear film instability and hyperosmolarity with resultant dry eye disease. The tear film is primarily composed of lipids, aqueous, and mucins, with aqueous accounting for most of its thickness. The aqueous is produced by the main lacrimal gland, accessory lacrimal glands, and corneal and conjunctival epithelia. Although the main lacrimal gland has long been considered an indispensable source of the aqueous component of tears, there is evidence that adequate tear secretion can exist in the absence of the main lacrimal gland. We review and discuss the basics of tear secretion, the tear secretory capacity of the ocular surface, and emerging treatments for dry eye disease.

Corneal and conjunctival sensitivity in rosacea patients

Purpose

To assess corneal and conjunctival sensitivity in rosacea patients.

Methods

A total of 55 patients with rosacea and 37 control subjects participated in the study. Corneal and conjunctival sensitivity was determined by Cochet-Bonnet esthesiometer. Subjective symptoms of ocular dryness were evaluated using Ocular Surface Disease Index (OSDI). Schirmer’s I test (ST), tear breakup time (tBUT) and ocular surface staining with fluorescein were carried out to measure objective signs.

Results

The mean corneal and conjunctival sensitivity did not differ significantly between rosacea patients and controls (all p > 0.05). Schirmer’s I test and tBUT were significantly reduced (p = 0.004 for OD and p < 0.001 for OS) and grade of ocular surface staining was significantly high (p = 0.018 for OD and p = 0.038 for OS) in rosacea patients. Corneal and conjunctival sensitivity did not show significant correlation with ST, tBUT, ocular surface staining (Oxford Schema), duration of rosacea and OSDI score.

Conclusions

Corneal and conjunctival sensitivity did not change significantly in rosacea.

Corneal Sensitivity and Presence of Pathogenic Organisms Among Participants Who Have Undergone Trichiasis Surgery Differ by Surgical Outcome

PURPOSE

To explore the potential association between reduced corneal sensation and/or conjunctival bacterial colonization and postoperative trichiasis and eyelid contour abnormalities after corrective eyelid surgery among participants with a history of trachomatous trichiasis.

METHODS

As an ancillary study to the Partnership for Rapid Elimination of Trachoma (PRET) Surgery Trial in southern Tanzania, we collected data on 580 PRET participants who had undergone trichiasis surgery 1 year earlier and 200 age-group-matched individuals without trichiasis. Assessments included eyelid status evaluation (presence and severity of postoperative trichiasis and/or eyelid contour abnormality), corneal sensitivity by Cochet-Bonnet aesthesiometer, a questionnaire on symptoms of ocular irritation, and conjunctival microbiology. We divided PRET participants based on their eyelid status and compared results across PRET groups and versus normals.

RESULTS

PRET participants had reduced corneal sensitivity compared with age-matched normals (mean sensitivity ranged from 2.8 to 3.8 cm in PRET participants vs. 5.9 cm in normals), and increasing severity of postoperative trichiasis was associated in a stepwise fashion with reduced corneal sensitivity (mean = 3.5 cm for mild and 2.6 cm for severe postoperative trichiasis). Conjunctival colonization with pathogenic bacteria was also associated with more severe postoperative trichiasis (Cochran-Armitage trend test P = 0.001) and with reduced corneal sensitivity (trend test P < 0.0001). Symptoms of ocular irritation were not associated with previous trichiasis surgery, postoperative trichiasis, or eyelid contour abnormality.

CONCLUSIONS

These findings indicate that reduced corneal sensitivity accompanies trachomatous trichiasis and suggest that reduced corneal sensitivity may play an important role in the harboring of pathogenic bacteria on the ocular surface.

Plasma Rich in Growth Factors for the Treatment of Ocular Surface Diseases

PURPOSE

The purpose of this work is to describe and review the technology of plasma rich in growth factors (PRGF), a novel blood derivative product, in the treatment of ocular surface disorders.

METHODS

To demonstrate the importance of this technology in the treatment of ocular pathologies, a thorough review of the preclinical and clinical literature results obtained following use of the different therapeutic formulations of PRGF was carried out. A literature search for applications of PGRF plasma in the ophthalmology field was carried out using the PubMed database.

RESULTS

PRGF involves the use of patient's own biologically active proteins, growth factors, and biomaterial scaffolds for therapeutic purposes. This procedural technology is gaining interest in regenerative medicine due to its potential to stimulate and accelerate the tissue healing processes. The versatility and biocompatibility of this technology opens the door to a personalized medicine on ocular tissue regeneration. This review discusses the state of the art of the new treatments and technologies developed to promote ocular surface tissue regeneration. The standardized protocol that has been developed to source eye drops from PRGF technology is also described. The preclinical research, together with the most relevant clinical applications are summarized and discussed.

CONCLUSIONS

The preliminary results suggest that the use of PRGF to enhance ocular tissue regeneration is safe and efficient.

Ocular Surface Epithelial Thickness Evaluation in Dry Eye Patients: Clinical Correlations

Purpose. To evaluate the relationship between corneal and conjunctival epithelium thickness and ocular surface clinical tests in dry eye disease (DED) patients. Patients and Methods. Fifty-four patients with DED and 32 control subjects were included. Each patient underwent an ocular surface evaluation using the ocular surface disease index (OSDI), tear film break-up time (TBUT), corneal and conjunctival staining, tear film lipid layer analysis, and Schirmer test. The central corneal (CET), limbal (LET), and bulbar conjunctival epithelium thickness (BET) were acquired using spectral-domain optical coherence tomography (SD-OCT). Results. Compared to control subjects, mean BET was significantly thicker and mean LET was significantly lower in the DED group. There was no significant difference in mean CET between the two groups. The mean LET was correlated with OSDI and TBUT. The inferior LET was correlated with OSDI, Schirmer I test, TBUT, Oxford score, and corneal sensitivity. Mean BET was correlated with OSDI and TBUT, but not with Schirmer I test and Oxford score. Conclusions. In dry eye patients, a thinner limbal epithelium and a thicker bulbar conjunctival epithelium were observed. These changes were correlated to the severity of dry eye symptoms and tear film alterations.

Outcomes of different concentrations of human amniotic fluid in a keratoconjunctivitis sicca-induced mouse model

To compare the effects of different concentrations of topical human amniotic fluid (HAF) in a mouse model of dry eye, forty C57BL/6 mice were divided into 4 treatment groups: 20 % HAF, 50 % HAF, 100 % HAF, and isotonic salt solution (control). Dry eye was induced by an injection of botulinum toxin B into the lacrimal gland. Tear production, ocular surface fluorescein staining, and blink rate were evaluated in each mouse at 5 time points during a 4-week period. Goblet cell density was assessed in stained histological sections. Regarding tear production, 20, 50, and 100 % HAF groups were all different from the control group (P < 0.001) at week 1. However, there were no statistically significant differences between the 20, 50, and 100 % HAF groups. At week 2, 20, 50, and 100 % HAF groups had significant improvement in staining score and were significantly different from the control group (P = 0.047, P = 0.005, and P = 0.001, respectively). No difference in spontaneous blink rate was observed between groups, at any time point. Goblet cell density was significantly decreased in the control group compared to the HAF treatment groups. All tested concentrations of topical HAF were effective and superior than the control in this keratoconjunctivitis sicca-induced mouse model. Further studies are needed to evaluate the effects of HAF on the human ocular surface.

Clinical and Molecular Inflammatory Response in Sjögren Syndrome-Associated Dry Eye Patients Under Desiccating Stress

PURPOSE

To evaluate the response of the lacrimal function unit in Sjögren syndrome (SS)-associated dry eye patients exposed to 2 simulated daily life environmental conditions.

DESIGN

Prospective crossover pilot study.

METHODS

Fourteen female SS dry eye patients were exposed for 2 hours to a controlled normal condition (23 C, 45% relative humidity, and air flow 0.10 m/s) and a controlled adverse condition that simulates desiccating stress (23 C, 5% relative humidity, and air flow 0.10 m/s). The following dry eye tests were performed before and after the exposure: tear osmolarity, phenol red thread test, conjunctival hyperemia, fluorescein tear break-up time, corneal fluorescein staining, conjunctival lissamine green staining, and Schirmer test. Levels of 16 molecules were analyzed in tears by multiplex immunobead analysis.

RESULTS

Clinical evaluation showed lacrimal functional unit impairment after the desiccating stress: significantly increased tear osmolarity (315.7 ± 3.0 vs 327.7 ± 5.1 mOsm/L, P = .03), conjunctival hyperemia (1.3 ± 0.1 vs 1.6 ± 0.1, P = .05), and corneal staining in temporal (3.5 ± 0.5 vs 4.7 ± 0.4, P = .01) and nasal (3.6 ± 0.5 vs 4.5 ± 0.5, P = .04) areas. Tear concentrations increased for interleukin-1 receptor antagonist (16 557.1 ± 4047.8 vs 31 895.3 ± 5916.5 pg/mL, P = .01), interleukin-6 (63.8 ± 20.2 vs 111.5 ± 29.6 pg/mL, P = .02), interleukin-8 (2196.1 ± 737.9 vs 3753.2 ± 1106.0 pg/mL, P = .03), and matrix metalloproteinase-9 (101 515.6 ± 37 088.4 vs 145 867.1 ± 41 651.5 pg/mL, P = .03). After the simulated normal condition, only a significant increase in nasal corneal staining (2.9 ± 0.5 vs 3.6 ± 0.5, P = .03) was observed.

CONCLUSIONS

Even a short exposure to a desiccating environment can produce a significant deterioration of the lacrimal function unit in female SS dry eye patients. The often unnoticed exposure to these conditions during daily life may increase inflammatory activity rapidly, triggering an ocular surface deterioration.

Understanding Neuropathic Corneal Pain--Gaps and Current Therapeutic Approaches

The richly innervated corneal tissue is one of the most powerful pain generators in the body. Corneal neuropathic pain results from dysfunctional nerves causing perceptions such as burning, stinging, eye-ache, and pain. Various inflammatory diseases, neurological diseases, and surgical interventions can be the underlying cause of corneal neuropathic pain. Recent efforts have been made by the scientific community to elucidate the pathophysiology and neurobiology of pain resulting from initially protective physiological reflexes, to a more persistent chronic state. The goal of this clinical review is to briefly summarize the pathophysiology of neuropathic corneal pain, describe how to systematically approach the diagnosis of these patients, and finally summarizing our experience with current therapeutic approaches for the treatment of corneal neuropathic pain.

Wakayama symposium: interface between innate and adaptive immunity in dry eye disease

Although the mechanism of dry eye disease is not clearly understood, it is certain that inflammation and the immune response play a major role in determining the health of the ocular surface in dry eye patients. Accurate ocular surface characterization during the early stages of dry eye disease is critical for successful treatment, because there exists no single standard, objective test to diagnose the early phase of dry eye disease. The treatment target should be direct to prevent the perpetuation of chronic inflammation and immune responses. Numerous studies have categorized dry eye disease as an autoimmune-related inflammatory disease. However, relatively little is known about how innate immune mechanisms act following a local insult, why some patients are particularly vulnerable, and why local inflammation fails to resolve in these patients. Within this review, particular attention will be given to the very early events and corresponding defense mechanism in dry eye disease. The transition from innate to adaptive immunity will also be discussed.

Understanding lymphangiogenesis in knockout models, the cornea, and ocular diseases for the development of therapeutic interventions

A major focus of cancer research for several decades has been understand the ability of tumors to induce new blood vessel formation, a process known as angiogenesis. Unfortunately, only limited success has been achieved in the clinical application of angiogenesis inhibitors. We now know that lymphangiogenesis, the growth of lymphatic vessels, likely also plays a major role in tumor progression. Thus, therapeutic strategies targeting lymphangiogenesis or both lymphangiogenesis and angiogenesis may represent promising approaches for treating cancer and other diseases. Importantly, research progress toward understanding lymphangiogenesis is significantly behind that related to angiogenesis. A PubMed search of "angiogenesis" returns nearly 80,000 articles, whereas a search of "lymphangiogenesis" returns 2,635 articles. This stark contrast can be explained by the lack of molecular markers for identifying the invisible lymphatic vasculature that persisted until less than 2 decades ago, combined with the intensity of research interest in angiogenesis during the past half century. Still, significant strides have been made in developing strategies to modulate lymphangiogenesis, largely using ocular disease models. Here we review the current knowledge of lymphangiogenesis in the context of knockout models, ocular diseases, the biology of activators and inhibitors, and the potential for therapeutic interventions targeting this process.

Meibomian gland dysfunction: hyperkeratinization or atrophy?

Meibomian gland dysfunction (MGD) is the major cause of evaporative dry eye disease (EDED) and dysfunction is widely thought to mechanistically involve ductal hyperkeratinization, plugging and obstruction. This review re-evaluates the role of hyperkeratinization in MGD based on more recent findings from mouse models. In these studies, eyelids from normal young and old mice or mice exposed to desiccating stress were evaluated by immunofluorescent tomography and 3-dimensional reconstruction to evaluate gland volume, expression of hyperkeratinization markers and cell proliferation or stimulated Raman scattering (SRS) microscopy to assess lipid quality. Results indicate that aging mice show dropout of meibomian glands with loss of gland volume and a forward migration of the mucocutaneous junction anterior to the gland orifice; similar age-related changes that are detected in human subjects. Atrophic glands also showed evidence of epithelial plugging of the orifice without the presence of hyperkeratinization. Mice exposed to desiccating stress showed hyperproliferation of the meibomian gland and ductal dilation suggesting a marked increase in lipid synthesis. Lipid quality was also affected in EDED mice with an increase in the protein content of lipid within the duct of the gland. Overall, age-related changes in the mouse show similar structural and functional correlates with that observed in clinical MGD without evidence of hyperkeratinization suggesting that gland atrophy may be a major cause of EDED. The response of the meibomian gland to desiccating stress also suggest that environmental conditions may accelerate or potentiate age-related changes.

Effects of Topical Fucosyl-Lactose, a Milk Oligosaccharide, on Dry Eye Model: An Example of Nutraceutical Candidate

Purpose: Colostrum has been proposed to treat severe dryness and problematic eye lesions showing a beneficial effect. The aim of the study was to investigate the effect of 2-fucosyl-lactose, a natural sugar present in the human colostrum, in an experimental dry eye.

Methods: Dry eye was induced in adult male New Zealand albino rabbits by topical administration of 1% atropine. Tear volume (Schirmer’s test), tear film breakup time (TBUT), corneal staining and tear osmolarity were assessed. Fucosyl-lactose eye drops was instilled at different concentrations (0.01, 0.1, and, 1%).

Results: After 24 h from first atropine administration, tear volume and TBUT values were significantly improved in groups treated with 2-fucosyl-lactose in a dose-dependent manner. Tear volume increased from 5.25 to 10.75 mm and TBUT values from 8.75 to 34.5 s with 0.01% or 1% 2-fucosyl-lactose treatment, respectively. No changes were observed in terms of corneal staining among the all groups treated with 2-fucosyl-lactose. Atropine instillation caused an increase of tear osmolarity (428 mOsm/L), which was reversed by topical treatment with 2-fucosyl-lactose at all doses.

Conclusion: The present study demonstrated that 2-fucosyl-lactose, a human milk oligosaccharide, has protective effect on tear film stability.

Relationship between symptoms of dry eye syndrome and occupational characteristics: the Korean National Health and Nutrition Examination Survey 2010-2012

Background

Dry Eye Syndrome (DES) is a broad spectrum of uncomfortable ocular conditions that are caused by reduced production of tears or an increased tear evaporation rate. This study evaluated the relationship between symptoms of DES and occupational characteristics to identify the occupation-dependent differences in the prevalence of symptoms of DES using the Korean National Health and Nutrition Examination Survey V (2010–2012) data.

Methods

A total of 6023 participants were included (3203 men and 2820 women). Questionnaires and physical examinations were used to record clinical characteristics, occupational characteristics and medical history. Odds ratios (ORs) and 95 % confidence intervals (95 % CIs) for symptoms of DES were calculated according to the occupational characteristics.

Results

Among the participants, 963 persons (16.0 %) had symptoms of DES. An increased risk (relative to the green-collar group) was observed for the ordinary white-collar (OR, 1.73; 95 % CI, 1.73–1.41), executive white-collar (OR, 1.40; 95 % CI, 1.02–1.92) and skilled blue-collar (OR, 1.44; 95 % CI, 1.04–2.00) groups. Furthermore, paid workers had a significantly higher risk of dry eye symptoms (OR, 1.21; 95 % CI, 1.02–1.45), compared to self-employed workers.

Conclusion

Our study is the first research to reveal that white-collar workers have a higher risk of symptoms of DES than blue-collar workers, that skilled blue-collar workers have a higher risk than unskilled blue-collar workers, and that paid workers have a higher risk than self-employed workers.

Role of Matrix Metalloproteinases 2 and 9 in Lacrimal Gland Disease in Animal Models of Sjögren's Syndrome

PURPOSE

Chronic inflammation of the lacrimal gland results in changes in the composition of the extracellular matrix (ECM), which is believed to compromise tissue repair. We hypothesized that increased production/activity of matrix metalloproteinases (MMPs), especially MMP-2 and -9, in inflamed lacrimal glands modifies the ECM environment, therefore disrupting tissue repair.

METHODS

The lacrimal glands from female MRL/lpr and male NOD mice along with their respective control strains were harvested and divided into three pieces and processed for histology, immunohistochemistry, zymography, Western blotting, and RNA analyses. In another study, MRL/lpr mice were treated for 5 weeks with a selective MMP2/9 inhibitor peptide or a control peptide. At the end of treatment, the lacrimal glands were excised and the tissue was processed as described above.

RESULTS

There was a 2.5- and 2.7-fold increase in MMP2 gene expression levels in MRL/lpr and NOD mice, respectively. Matrix metalloproteinase 2 and 9 enzymatic activities and protein expression levels were significantly upregulated in the lacrimal glands of MRL/lpr and NOD mice compared to controls. Treatment with the MMP2/9 inhibitor resulted in decreased activity of MMP-2 and -9 both in vitro and in vivo. Importantly, MMP2/9 inhibitor treatment of MRL/lpr mice improved aqueous tear production and resulted in reduced number and size of lymphocytic foci in diseased lacrimal glands.

CONCLUSIONS

We conclude that MMP2/9 expression and activity are elevated in lacrimal glands of two murine models of Sjögren's syndrome, suggesting that manipulation of MMP2/9 activity might be a potential therapeutic target in chronically inflamed lacrimal glands.

Protective Effects of L-Carnitine Against Oxidative Injury by Hyperosmolarity in Human Corneal Epithelial Cells

PURPOSE

L-carnitine suppresses inflammatory responses in human corneal epithelial cells (HCECs) exposed to hyperosmotic stress. In this study, we determined if L-carnitine induces this protective effect through suppression of reactive oxygen species (ROS)-induced oxidative damage in HCECs.

METHODS

Primary HCECs were established from donor limbal explants. A hyperosmolarity dry-eye model was used in which HCECs are cultured in 450 mOsM medium with or without L-carnitine for up to 48 hours. Production of reactive oxygen species (ROS), oxidative damage markers, oxygenases and antioxidative enzymes were analyzed by 2',7'-dichlorofluorescein diacetate (DCFDA) kit, semiquantitative PCR, immunofluorescence, and/or Western blotting.

RESULTS

Reactive oxygen species production increased in HCECs upon substitution of the isotonic medium with the hypertonic medium. L-carnitine supplementation partially suppressed this response. Hyperosmolarity increased cytotoxic membrane lipid peroxidation levels; namely, malondialdehyde (MDA) and hydroxynonenal (HNE), as well as mitochondria DNA release along with an increase in 8-OHdG and aconitase-2. Interestingly, these oxidative markers were significantly decreased by coculture with L-carnitine. Hyperosmotic stress also increased the mRNA expression and/or protein production of heme oxygenase-1 (HMOX1) and cyclooxygenase-2 (COX2), but inhibited the levels of antioxidant enzymes, superoxide dismutase-1 (SOD1), glutathione peroxidase-1 (GPX1), and peroxiredoxin-4 (PRDX4). However, L-carnitine partially reversed this altered imbalance between oxygenases and antioxidant enzymes induced by hyperosmolarity.

CONCLUSIONS

Our findings demonstrate for the first time that L-carnitine protects HCECs from oxidative stress by lessening the declines in antioxidant enzymes and suppressing ROS production. Such suppression reduces membrane lipid oxidative damage markers and mitochondrial DNA damage.

Corneal Sensitivity and Dry Eye Symptoms in Patients with Keratoconus

PURPOSE

To investigate corneal sensitivity to selective mechanical, chemical, and thermal stimulation and to evaluate their relation to dry eye symptoms in patients with keratoconus.

METHODS

Corneal sensitivity to mechanical, chemical, and thermal thresholds were determined using a gas esthesiometer in 19 patients with keratoconus (KC group) and in 20 age-matched healthy subjects (control group). Tear film dynamics was assessed by Schirmer I test and by the non-invasive tear film breakup time (NI-BUT). All eyes were examined with a rotating Scheimpflug camera to assess keratoconus severity.

RESULTS

KC patients had significatly decreased tear secretion and significantly higher ocular surface disease index (OSDI) scores compared to controls (5.3±2.2 vs. 13.2±2.0 mm and 26.8±15.8 vs. 8.1±2.3; p<0.001). There was no significant difference in NI-BUT between the two groups (KC: 9.8±4.8 vs. control: 10.7±3.8; p>0.05). The mean threshold for selective mechanical (KC: 139.2±25.8 vs. control: 109.1±24.0 ml/min), chemical (KC: 39.4±3.9 vs. control: 35.2±1.9%CO2), heat (KC: 0.91±0.32 vs. control: 0.54±0.26 Δ°C) and cold (KC: 1.28±0.27 vs. control: 0.98±0.25 Δ°C) stimulation in the KC patients were significantly higher than in the control subjects (p<0.001, for all parameters). No correlation was found between age and mechanical, chemical, heat or cold thresholds in the patients with KC (p>0.05), whereas in the control subjects both mechanical (r = 0.52, p = 0.02), chemical (r = 0.47, p = 0.04), heat (r = 0.26, p = 0.04) and cold threshold (r = 0.40, p = 0.03) increased with age. In the KC group, neither corneal thickness nor tear flow, NI-BUT or OSDI correlated significantly with mechanical, chemical, heat or cold thresholds (p>0.05 for all variables).

CONCLUSIONS

Corneal sensitivity to different types of stimuli is decreased in patients with keratoconus independently of age and disease severity. The reduction of the sensory input from corneal nerves may contribute to the onset of unpleasant sensations in these patients and might lead to the impaired tear film dynamics.

Age-Related Conjunctival Disease in the C57BL/6.NOD-Aec1Aec2 Mouse Model of Sjögren Syndrome Develops Independent of Lacrimal Dysfunction

PURPOSE

To investigate parameters of ocular surface disease in C57BL/6.NOD-Aec1Aec2 (Aec) mice with aging and their correlation with development of Sjögren syndrome (SS)-like lacrimal gland (LG) disease.

METHODS

Aec and C57BL/6 wild-type (B6) female mice were evaluated at 4, 12, and 20 weeks of age. Whole LG and eyes and adnexa were excised for histology and gene expression analysis and evaluated by flow cytometry and immunohistochemistry. Tear volume and goblet cell density was measured. Quantitative PCR evaluated T-cell-related cytokine expression in cornea and conjunctiva.

RESULTS

Both strains showed age-related conjunctival goblet cell loss that was more pronounced in the Aec strain and significantly greater than in B6 mice at 12 weeks. This was accompanied by CD4+ T-cell infiltration of the conjunctiva that was greater in Aec strain at 20 weeks. Aec mice had higher levels of IL-17A, IL-17R, IL-1α, IL-1β, and TNF-α in the conjunctiva, and they significantly increase with aging. Aec mice had greater lymphocytic infiltration of the LG and conjunctiva at 20 weeks that consisted of a mixture of CD4+ and CD8+ cells. Flow cytometry showed a significant increase in CD4+ T cells in Aec LG compared to B6 mice. Tear volume was significantly increased in both strains at 20 weeks.

CONCLUSIONS

Aec mice developed greater conjunctival goblet cell loss associated with lymphocytic infiltration of the LG and conjunctiva with aging. Increased expression of certain T helper or inflammatory cytokines in these tissues was observed in Aec mice. The conjunctival disease appeared to be due to inflammation and not a decrease in tear volume.

Degeneration and Regeneration of Subbasal Corneal Nerves after Infectious Keratitis: A Longitudinal In Vivo Confocal Microscopy Study

PURPOSE

To investigate the longitudinal alterations of subbasal corneal nerves in patients with infectious keratitis (IK) during the acute phase, cessation of treatment, and the recovery phase by in vivo confocal microscopy (IVCM).

DESIGN

Prospective, longitudinal, case-control, single-center study.

PARTICIPANTS

Fifty-six eyes of 56 patients with the diagnosis of bacterial (n=28), fungal (n=15), or Acanthamoeba (n=13) keratitis were included in the study. Thirty eyes of 30 normal volunteers constituted the control group.

METHODS

Corneal sensation and serial IVCM of the central cornea were performed prospectively using the Heidelberg Retina Tomograph 3/Rostock Cornea Module (Heidelberg Engineering, Heidelberg, Germany). The IVCM images were assessed at 3 time points: at the acute phase (first visit to the cornea service), at cessation of antimicrobial treatment, and up to 6 months after the resolution of infection.

MAIN OUTCOME MEASURES

Total nerve number and length, main nerve trunks, branching, and corneal sensation were assessed during the follow-up period.

RESULTS

Corneal nerves were reduced significantly during the acute phase in eyes with IK compared with controls across all subgroups, with total nerve length of 5.47±0.69 mm/mm2 versus 20.59±1.06 mm/mm2 (P<0.0001). At the cessation of treatment, corneal nerves in patients with IK had regenerated, including total nerve length (8.49±0.94 mm/mm2; P=0.02) and nerve branch length (4.80±0.37 mm/mm2; P=0.005). During the recovery phase, after resolution of infection, corneal nerves regenerated further, including total nerve length (12.13±1.97 mm/mm2; P=0.005), main nerve trunk length (5.80±1.00 mm/mm2; P=0.01), and nerve branch length (6.33±0.76 mm/mm2; P=0.003) as compared with the acute phase, but were still significantly lower when compared with controls (P<0.05 for all parameters). Corneal degeneration and regeneration correlated with corneal sensation (r=0.47; P=0.0009).

CONCLUSIONS

Patients with IK who sustain profound loss of corneal nerves during the acute phase of infection demonstrate increased corneal nerve density during the first 6 months after the resolution of infection. However, despite significant nerve regeneration, corneal nerve density does not recover fully and remains low compared to controls. By providing an objective methodology to monitor corneal re-innervation, IVCM adds potentially important findings that may have implications for clinical management and surgical planning.

The role of nanotechnology in control of human diseases: perspectives in ocular surface diseases

Nanotechnology is the creation and use of materials and devices on the same scale as molecules and intracellular structures, typically less than 100 nm in size. It is an emerging science and has made its way into pharmaceuticals to significantly improve the delivery and efficacy of drugs in a number of therapeutic areas, due to development of various nanoparticle-based products. In recent years, there has been increasing evidence that nanotechnology can help to overcome many of the ocular diseases and hence researchers are keenly interested in this science. Nanomedicines offer promise as viable alternatives to conventional drops, gels or ointments to improve drug delivery to the eye. Because of their small size, they are well tolerated, thus preventing washout, increase bioavailability and also help in specific drug delivery. This review describes the application of nanotechnology in the control of human diseases with special emphasis on various eye and ocular surfaces diseases.

FTY720 ameliorates Dry Eye Disease in NOD mice: Involvement of leukocytes inhibition and goblet cells regeneration in ocular surface tissue

FTY720 is a promising drug in attenuating multiple sclerosis, prolonging survival of organ allograft, and many other protective effects. Its mechanism of action is considered to be mediated by the internalization of sphingosine 1-phosphate receptors (S1PRs). In the current study, we investigated the efficacy of FTY720 in Non-Obese Diabetic (NOD) mice, serving as a model of Dry Eye Disease (DED). NOD mice were divided into six study groups, i.e., FTY720-treated groups with 3 concentrations of FTY720 (0.05%, 0.005%, and 0.001%), 0.05% Cyclosporin A (CsA) treated group, normal saline treated group, and no treatment control group. FTY720 was reconstituted with normal saline and prepared as eye drop. The stability and production of tear film was measured by Tear Break up Time test (TBUT) and phenol red cotton thread test (PRCTT), respectively. Tear fluid washings were collected and assessed by ELISA. Cytokines were detected in lacrimal glands by RT-PCR. Inflammation in conjunctiva was assessed by immunohistochemistry, goblet cells and conjunctival epithelia were examined and evaluated by impression cytology. Our results indicated that FTY720 had a significantly therapeutic effect in NOD mice. After FTY720 intervention, TBUT and PRCTT data were greatly improved (p < 0.01), the interleukin 1β (IL-1β) level was markedly decreased in tear fluid washings compared to control and normal saline groups after 2 weeks (

CONTROL

1.06 ± 0.12, Normal saline:0.97 ± 0.09 pg/ml, CsA:0.22 ± 0.02 pg/ml, 0.001% FTY720:0.23 ± 0.02 pg/ml, 0.005% FTY720:0.14 ± 0.03 pg/ml, 0.05% FTY720: 0.18 ± 0.03 pg/ml. CsA group and 3 FTY720 groups VS. control group and normal saline groups: p < 0.01). Proinflammatory factors were greatly decreased in lacrimal glands (p < 0.01). Leukocytes were identified and markedly decreased in conujnctiva (p < 0.01), inflammatory reaction of DED was greatly relieved. More importantly, the goblet cells were largely restored and ocular surface lesions were significantly ameliorated (p < 0.01). Thus, we observed FTY720 alleviated DED in NOD mice by inhibiting leukocytes, the function of ocular surface tissue in NOD mice was partially restored via inhibiting ocular surface inflammation and increasing the density of goblet cells and conjunctival epithelia. FTY720 may offer a novel strategy for the treatment of inflammatory disorders in the ocular surface.

Thrombospondin-1 as a Regulator of Corneal Inflammation and Lymphangiogenesis: Effects on Dry Eye Disease and Corneal Graft Immunology

Thrombospondin-1 (TSP-1) is a matricellular glycoprotein that belongs to a family of evolutionary highly conserved calcium-binding proteins consisting of 5 members (TSP-1-TSP-5). In the eye, TSP-1 is expressed by several ocular cell types and is also detectable in the aqueous humor and the vitreous body. So far, TSP-1 is one of the major activators of TGFβ, suggesting a strong influence on various important cellular functions and interactions such as differentiation, migration, and wound healing. TSP-1 is also a key endogenous inhibitor of hem- and lymphangiogenesis. Several lines of evidence indicate a crucial role of TSP-1 in maintaining the ocular immune and angiogenic privilege, for example, by regulating T lymphocytes and the tolerance-promoting properties of ocular antigen-presenting cells. This review discusses the role of TSP-1 in dry eye disease and corneal graft rejection through its effects on hem- and lymphangiogenesis, as well as on the underlying immune responses. Recent work will be reviewed showing by which molecular mechanism TSP-1 modulates inflammatory processes during ocular diseases. This opens potential new treatment avenues in inflammatory and (lymph)angiogenic ocular diseases.

Effects of Dry Eye Therapies on Environmentally Induced Ocular Surface Disease

PURPOSE

To evaluate the effectiveness of artificial tears and corticosteroids on mitigating the acute ocular surface response to low-humidity environments.

DESIGN

Single-group, crossover clinical trial.

METHODS

Twenty subjects with aqueous deficient dry eye were enrolled. Subjects meeting inclusion criteria at visit 1 were exposed to a baseline 90-minute low-humidity environment at visit 2. They then used artificial tears for 2 weeks prior to low-humidity exposure at visit 3, followed by 0.1% dexamethasone for 2 weeks prior to the final low-humidity exposure at visit 4. Outcome measures included corneal and conjunctival staining, blink rate, and irritation symptoms before and after each low-humidity exposure. Digital polymerase chain reaction (PCR) was performed to measure HLA-DR RNA transcripts in conjunctival cells taken by impression cytology at each visit.

RESULTS

There was significantly less corneal and conjunctival epitheliopathy after the low-humidity exposure at visit 4 compared to after the low-humidity exposure at visit 3 (P = .003). Subjects reported significantly less eye irritation during the low-humidity exposure after using the dexamethasone (visit 4) compared to artificial tears (visit 3) (P = .01). HLA-DR transcripts significantly decreased after the stress at visit 4 (post dexamethasone) compared to visit 2.

CONCLUSION

Our study demonstrates that corticosteroid eye drops mitigate the acute adverse effects of an experimental low-humidity challenge, likely owing to suppression of stress-activated inflammatory pathways. While extended use of corticosteroids is not indicated, other anti-inflammatory therapies with activity against stress-activated pathways may prove as effective.

Liposomal voriconazole (VOR) formulation for improved ocular delivery

Treating infectious eye diseases topically requires a drug delivery system capable of overcoming the eye's defense mechanisms, which efficiently reduce the drug residence time right after its administration, therefore reducing absorption. In order to try to surpass such administration issues and improve life quality for patients with fungal keratitis, liposomal voriconazol (VOR) formulations were prepared. Formulations were composed of soy phosphatidylcholine (PC) containing or not 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and cholesterol. Liposomes were characterized by their drug entrapment efficiency (EE), drug recovery (DR), average diameter (size) and polydispersivity index (PdI). In vitro mucosal interaction and irritancy levels, ex vivo permeation, as well as the short-term stability were also assessed. Liposomal VOR formulation produced with 7.2:40mM VOR:PC showed to be the most promising formulation: mean size of 116.6±5.9nm, narrow PdI (0.17±0.06), negative zeta potential (∼-7mV) and over 80% of EE and yield, remaining stable for at least 30 days in solution and 90 days after lyophilization. This formulation was classified as 'non-irritant' after HET-CAM's test and was able to deliver about 47.85±5.72μg/cm(2) of VOR into porcine cornea after 30min of permeation test. Such drug levels are higher than the minimal inhibitory concentrations (MIC) of several fungi species isolated from clinical cases of corneal keratitis. Overall results suggest VOR can be effectively incorporated in liposomes for potential topical treatment of fungal keratitis.

Dry eye after laser in-situ keratomileusis

Laser-assisted in-situ keratomileusis (LASIK) is one of the most commonly performed refractive procedures with excellent visual outcomes. Dry eye syndrome is one of the most frequently seen complications after LASIK, with most patients developing at least some mild dry eye symptoms postoperatively. To achieve improved visual outcomes and greater patient satisfaction, it is essential to identify patients prone to dry eyes preoperatively, and initiate treatment early in the course. Enhanced understanding of the pathophysiology of post-LASIK dry eye will help advance our approach to its management.

Extraorbital lacrimal gland excision: a reproducible model of severe aqueous tear-deficient dry eye disease

PURPOSE

The aim of this study was to establish and characterize extraorbital lacrimal gland excision (LGE) as a model of aqueous tear-deficient dry eye disease in mice.

METHODS

Female C57BL/6 mice at 6 to 8 weeks of age were randomized to extraorbital LGE, sham surgery, or scopolamine groups. Mice that underwent extraorbital LGE or sham surgery were housed in the standard vivarium. Scopolamine-treated mice were housed in a controlled environment chamber that allowed for the continuous regulation of airflow (15 L/min), relative humidity (30%), and temperature (21-23°C). Clinical disease severity was assessed over the course of 14 days using the phenol red thread test and corneal fluorescein staining. Real-time polymerase chain reaction was performed to assess corneal mRNA expression of interleukin 1β, tumor necrosis factor α, and matrix metalloproteinase 9. Flow cytometry was used to assess T helper cell frequencies in the conjunctivae and draining lymph nodes.

RESULTS

Extraorbital LGE markedly reduced aqueous tear secretion as compared with the sham procedure and induced a more consistent decrease in aqueous tear secretion than was observed in mice that received scopolamine while housed in the controlled environment chamber. Extraorbital LGE significantly increased corneal fluorescein staining scores as compared with those of both the sham surgery and scopolamine-treated groups. Extraorbital LGE significantly increased the corneal expression of interleukin 1β, tumor necrosis factor α, and matrix metalloproteinase 9. Further, extraorbital LGE increased T helper 17-cell frequencies in the conjunctivae and draining lymph nodes.

CONCLUSIONS

Extraorbital LGE induces aqueous tear-deficient dry eye disease in mice as evidenced by decreased aqueous tear secretion, increased corneal epitheliopathy, and induced ocular surface inflammation and immunity.

Efficacy and Safety of Topical 0.05% Cyclosporine Eye Drops in the Treatment of Dry Eye Syndrome: A Systematic Review and Meta-analysis

A systematic review was performed to evaluate the safety and efficacy of topical 0.05% cyclosporine in treating patients with dry eye syndrome (DES). Twelve qualified randomized-controlled trials incorporating 1367 patients were analyzed. In comparison to controls, patients who were on topical 0.05% cyclosporine eye drops had lower Ocular Surface Disease Index scores (mean difference [MD]=4.10, 95% CI: 0.25-7.96, P=.04), longer tear film breakup time (MD=2.30 seconds, 95% CI: 0.75-3.86, P=.004), improved Schirmer I scores (MD=2.77 mm/5min, 95% CI: 1.63-3.91, P=.00001), reduced corneal fluorescein staining (standardized mean difference [SMD]=0.61, 95% CI: 0.07-1.15, P=.03), and higher goblet cell densities (SMD=1.68, 95% CI: 0.54-2.81, P=.004). However, there were more adverse effects in the cyclosporine patient group (odds ratio=1.64, 95% CI: 1.17-2.30, P=.004). Topical 0.05% cyclosporine eye drops twice daily significantly improved both the objective and subjective outcomes in DES patients. The study limitations in the clinical, methodological and statistical heterogeneities are discussed.

Corneal nerve structure and function after long-term wear of fluid-filled scleral lens

PURPOSE

The aim of this study was to determine whether long-term wear of a fluid-filled scleral lens alters basal tear production, corneal sensation, corneal nerve density, and corneal nerve morphology in 2 disease categories.

METHODS

Patients recruited from the Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) treatment program at the Weill Cornell Medical College were categorized into 2 groups: distorted corneas (DC) or ocular surface disease (OSD). We measured tear production, central corneal sensation, subbasal nerve density and tortuosity, and stromal nerve thickness before and after long-term wear of the prosthetic device used in PROSE treatment, defined as at least 60 days of wear for a minimum of 8 hours a day.

RESULTS

Twenty patients were included in the study. After long-term wear of the prosthetic device, tear production decreased in patients with DC (21.2 ± 8.5 to 10.4 ± 4.6 mm; P < 0.0001) but did not change in patients with OSD (7.5 ± 5.2 to 8.7 ± 7.2 mm; P = 0.71). Corneal sensation increased in the DC group (45.6 ± 9.2 to 55.0 ± 5.6 mm; P < 0.05). There was no significant change in sensation in patients with OSD (45.0 ± 8.7 to 49.1 ± 14.8 mm; P = 0.37). Subbasal nerve density, subbasal nerve tortuosity, and stromal nerve thickness remained unchanged in both DC and OSD groups after long-term wear (P > 0.05).

CONCLUSIONS

Patients with DC had significantly reduced basal tear production and increased corneal sensation after long-term wear of the scleral lens, but patients with OSD did not show any changes in tear production or corneal sensation.

Efficacy of the mineral oil and hyaluronic acid mixture eye drops in murine dry eye

Purpose

To investigate the therapeutic effects of mineral oil (MO) and hyaluronic acid (HA) mixture eye drops on the tear film and ocular surface in a mouse model of experimental dry eye (EDE).

Methods

Eye drops consisting of 0.1% HA alone or mixed with 0.1%, 0.5%, or 5.0% MO were applied to desiccating stress-induced murine dry eyes. Tear volume, corneal irregularity score, tear film break-up time (TBUT), and corneal fluorescein staining scores were measured at 5 and 10 days after treatment. Ten days after treatment, goblet cells in the conjunctiva were counted after Periodic acid-Schiff staining.

Results

There was no significant difference in the tear volume between desiccating stress-induced groups. The corneal irregularity score was lower in the 0.5% MO group compared with the EDE and HA groups. The 0.5% and 5.0% MO groups showed a significant improvement in TBUT compared with the EDE group. Mice treated with 0.1% and 0.5% MO mixture eye drops showed a significant improvement in fluorescein staining scores compared with the EDE group and the HA group. The conjunctival goblet cell count was higher in the 0.5% MO group compared with the EDE group and HA group.

Conclusions

The MO and HA mixture eye drops had a beneficial effect on the tear films and ocular surface of murine dry eye. The application of 0.5% MO and 0.1% HA mixture eye drops could improve corneal irregularity, the corneal fluorescein staining score, and conjunctival goblet cell count compared with 0.1% HA eye drops in the treatment of EDE.

Botulinum toxin injection for the treatment of epiphora in lacrimal outflow obstruction

PURPOSE

To describe our experience with the use of botulinum toxin (BoNTA) for the symptomatic treatment of lacrimal outflow obstruction.

METHODS

We retrospectively reviewed the case notes of patients with epiphora due to lacrimal outflow obstruction who chose to have injections of botulinum toxin into the palpebral lobe of the lacrimal gland instead of surgery between 2009 and 2014. Epiphora was graded subjectively with Munk scores obtained before and after treatment as well as qualitative degree of improvement reported by the patients. Severity and duration of side effects were also noted.

RESULTS

Seventeen patients (22 eyes, mean age 70.3, 4 males and 13 females) were identified. A mean of 3.5 (range; 1-10) injections of BoNTA (Botox, Allergan; 1.25-7.5 units) were given per eye. The mean interval between injections was 3.9 months (range 3-6). The mean Munk score (3.4, range 2-4) improved significantly after treatment to 1.6 (range: 0-3, P=0.0001 paired two-tailed t-test). Epiphora completely resolved in a fifth, improved by up to 60-90% in a half and only 'a little better' in a further fifth. Temporary bruising and diplopia (lasting 2 weeks) was reported in 12% (2/17).

CONCLUSION

We report our outcomes for BoNTA to the palpebral lobe of the lacrimal gland in patients with lacrimal outflow obstruction epiphora seeking alternatives to surgery. This data provide further evidence for informed consent and for commissioning organisations considering the funding of this treatment.

Effect of non-invasive tear stability assessment on tear meniscus height

PURPOSE

To investigate the effect of non-invasive tear stability assessment with forced eye opening on the lower tear meniscus.

METHODS

Twenty-three eyes of 23 patients with aqueous-deficient dry eye and 23 eyes of 23 normal subjects were enrolled. All subjects underwent imaging with a Keratograph 5M equipped with a modified tear film scanning function. Lower tear meniscus images were captured, and tear meniscus height (TMH) was measured with an integrated ruler before and after non-invasive Keratograph break-up time (NIKBUT) measurements in each subject. Subjects were instructed to keep their eyes open as long as possible during NIKBUT measurements, and the recording was discontinued at the next blink.

RESULTS

The TMH values of the normal and dry eye groups were 0.20±0.05 mm and 0.14±0.03 mm, respectively, at baseline. The TMH values of dry eyes were significantly smaller than those of normal eyes (p<0.001). Significant increases in TMH values were observed in both normal (0.10±0.12 mm) and dry eyes (0.04±0.09 mm) with the NIKBUT measurement (p<0.001, p=0.039). A moderate negative correlation was observed between increased TMH and baseline TMH in dry eyes (r=-0.44, p=0.03), whereas no correlation was observed in normal eyes (r=0.04, p=0.85).

CONCLUSIONS

Forced eye opening required for the non-invasive tear stability assessment influences the TMH measurement possibly due to reflex tear secretion, even in patients with aqueous-deficient dry eye. TMH should be assessed before tests that require forced eye opening.

Neurostimulation of the lacrimal nerve for enhanced tear production

PURPOSE

To design a proof-of-concept study to assess the effect of lacrimal nerve stimulation (LNS) with an implantable pulse generator (IPG) to increase aqueous tear production.

METHODS

Experimental animal study design of 6 Dutch Belted rabbits. Ultra high-resolution optical coherence tomography (UHR-OCT) quantified tear production by measuring the baseline tear volume of each rabbit's OD and OS. A neurostimulator was implanted adjacent to the right lacrimal nerve. After 2 minutes of LNS (100 μs, 1.6 mA, 20 Hz, 5-8 V), the tear volumes were measured with UHR-OCT. The change in tear volume was quantified and compared with the nonstimulated OS. Three rabbits underwent chronic LNS (100 μs, 1.6 mA, 10 Hz, 2 V) and their lacrimal glands were harvested for histopathologic analysis.

RESULTS

The UHR-OCT imaging of the OD tear volume showed a 441% average increase in tear production after LNS as a percent of baseline. After stimulation, OD had statistically significant greater increase in tear volumes than OS (p = 0.028, Wilcoxon test). Poststimulation OD tear volumes were significantly greater compared with baseline (p = 0.028, Wilcoxon test). Histopathologic examination of the lacrimal glands showed no discernible tissue damage from chronic neurostimulation. In addition, there were no gross adverse effects on the general well-being of the animals due to chronic stimulation.

CONCLUSIONS

LNS with an IPG appears to increase aqueous tear production. Chronic LNS showed no histopathologic lacrimal gland damage. This study suggests that LNS is a promising new treatment strategy to increase aqueous tear production.

Topical cyclosporine a for treatment of dry eye due to chronic mustard gas injury

Purpose:

To evaluate the efficacy of topical cyclosporine A (tCsA) for treatment of dry eye disease in patients suffering from chronic ocular complications of mustard gas (MG) injury.

Methods:

This interventional case series included patients with MG injury suffering from severe dry eye despite receiving artificial tears and punctal plugs. Patients were administered tCsA 0.05% twice daily for 3 months. Severity of the condition was evaluated by measuring tear osmolarity, ocular surface disease index (OSDI), tear break-up time (TBUT), and Schirmer's test at baseline and at the end of study.

Results:

A total of 34 patients with chronic MG injury and mean age of 47.1 ± 6.5 years were studied. Compared to baseline values, tear osmolarity (301.7 ± 11.5 vs. 286.3 ± 7.9 mOsmol/L, P < 0.001) and OSDI (47.5 ± 7.2 vs. 42.7 ± 7.1, P < 0.001) were significantly improved. Likewise, Schirmer's test (4.6 ± 1.3 vs. 5 ± 1.3 mm, P < 0.001) and TBUT (1.9 ± 1.4 vs. 2.7 ± 1.5 s, P < 0.001) also significantly recovered at the end of the study.

Conclusion:

TCsA 0.05% reduces tear osmolarity and improves dry eye symptoms and can serve as an efficacious treatment for ocular complications in patients with chronic MG injury.

Fourier-domain optical coherence tomography for monitoring the lower tear meniscus in dry eye after acupuncture treatment

Dry eye is highly prevalent and has a significant impact on quality of life. Acupuncture was found to be effective to treat dry eye. However, little was known about the effect of acupuncture on different subtypes of dry eye. The objective of this study was to investigate the applicability of tear meniscus assessment by Fourier-domain optical coherence tomography in the evaluation of acupuncture treatment response in dry eye patients and to explore the effect of acupuncture on different subtypes of dry eye compared with artificial tear treatment. A total of 108 dry eye patients were randomized into acupuncture or artificial tear group. Each group was divided into three subgroups including lipid tear deficiency (LTD), Sjögren syndrome dry eye (SSDE), and non-Sjögren syndrome dry eye (Non-SSDE) for data analysis. After 4-week treatment, the low tear meniscus parameters including tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA) in the acupuncture group increased significantly for the LTD and Non-SSDE subgroups compared with both the baseline and the control groups (all P values < 0.05), but not for the SSDE. Acupuncture provided a measurable improvement of the tear meniscus dimensions for the Non-SSDE and LTD patients, but not for the SSDE patients.

Evidence for TRPA1 involvement in central neural mechanisms in a rat model of dry eye

Dry eye (DE) disease is commonly associated with ocular surface inflammation, an unstable tear film and symptoms of irritation. However, little is known about the role of central neural mechanisms in DE. This study used a model for persistent aqueous tear deficiency, exorbital gland removal, to assess the effects of mustard oil (MO), a transient receptor potential ankyrin (TRPA1) agonist, on eyeblink and eyewipe behavior and Fos-like immunoreactivity (Fos-LI) in the trigeminal brainstem of male rats. Spontaneous tear secretion was reduced by about 50% and spontaneous eyeblinks were increased more than 100% in DE rats compared to sham rats. MO (0.02-0.2%) caused dose-related increases in eyeblink and forelimb eyewipe behavior in DE and sham rats. Exorbital gland removal alone was sufficient to increase Fos-LI at the ventrolateral pole of trigeminal interpolaris/caudalis (Vi/Vc) transition region, but not at more caudal regions of the trigeminal brainstem. Under barbiturate anesthesia ocular surface application of MO (2-20%) produced Fos-LI in the Vi/Vc transition, in the mid-portions of Vc and in the trigeminal caudalis/upper cervical spinal cord (Vc/C1) region that was significantly greater in DE rats than in sham controls. MO caused an increase in Fos-LI ipsilaterally in superficial laminae at the mid-Vc and Vc/C1 regions in a dose-dependent manner. Smaller, but significant, increases in Fos-LI also were seen in the contralateral Vc/C1 region in DE rats. TRPA1 protein levels in trigeminal ganglia from DE rats ipsilateral and contralateral to gland removal were similar. Persistent tear reduction enhanced the behavioral and trigeminal brainstem neural responses to ocular surface stimulation by MO. These results suggested that TRPA1 mechanisms play a significant role in the sensitization of ocular-responsive trigeminal brainstem neurons in this model for tear deficient DE.

Efficacy of hypotonic 0.18% sodium hyaluronate eye drops in patients with dry eye disease

PURPOSE

The aim of this study was to evaluate the efficacy of hypotonic 0.18% sodium hyaluronate (SH) eye drops under the clinical settings of the dry eye workshop treatment guideline for mild dry eye disease (DED).

METHODS

This analysis included 60 patients with DED. Patients with level 1 DED were treated with either isotonic 0.1% SH (group 1) or with hypotonic 0.18% SH eye drops (group 2). Patients with level 2 DED were treated with 0.1% fluorometholone, 0.05% cyclosporine A, and either isotonic 0.1% SH (group 3) or hypotonic 0.18% SH (group 4) eye drops. Tear film breakup time (TBUT), Schirmer test, corneal staining with fluorescein, and ocular surface disease index score were recorded at baseline, 1 month, and 3 months after treatment.

RESULTS

In group 2, TBUT at 3 months (P = 0.03) and corneal staining scores at 1 and 3 months (P ≤ 0.03) were significantly improved after the treatment compared with baseline scores, whereas these parameters were not changed during the follow-up period in group 1. In groups 3 and 4, TBUT and corneal staining scores at 1 and 3 months, and ocular surface disease index score and Schirmer test results at 3 months after the treatment showed significant improvements compared with the baseline score (P < 0.05). Group 4 patients showed an extended TBUT and an improved corneal staining score (P ≤ 0.01) at 3 months after treatment, compared with the values of group 3.

CONCLUSIONS

Hypotonic 0.18% SH eye drops seemed to be effective in improving tear film stability and ocular surface integrity compared with isotonic 0.1% SH eye drops in patients with mild DED.

Dynamic ocular surface and lacrimal gland changes induced in experimental murine dry eye

Dry eye disease can be a consequence of lacrimal gland insufficiency in Sjögren’s Syndrome or increased tear film evaporation despite normal lacrimal gland function. To determine if there is a correlation between severity effects in these models and underlying pathophysiological responses, we compared the time dependent changes in each of these parameters that occur during a 6 week period. Dry eye was induced in 6-week-old female C57BL/6 mice by exposing them to an Intelligently Controlled Environmental System (ICES). Sixty mice were housed in ICES for 1, 2, 4 and 6 weeks respectively. Twelve were raised in normal environment and received subcutaneous injections of scopolamine hydrobromide (SCOP) 3 times daily for 5 days. Another sixty mice were housed in a normal environment and received no treatment. Corneal fluorescein staining along with corneal MMP-9 and caspase-3 level measurements were performed in parallel with the TUNEL assay. Interleukin-17(IL-17), IL-23, IL-6, IL-1, TNF-α, IFN-γ and TGF-β2 levels were estimated by real-time PCR measurements of conjunctival and lacrimal gland samples (LGs). Immunohistochemistry of excised LGs along with flow cytometry in cervical lymph nodes evaluated immune cell infiltration. Light and transmission electron microscopy studies evaluated LGs cytoarchitectural changes. ICES induced corneal epithelial destruction and apoptosis peaked at 2 weeks and kept stable in the following 4 weeks. In the ICES group, lacrimal gland proinflammatory cytokine level increases were much lower than those in the SCOP group. In accord with the lower proinflammatory cytokine levels, in the ICES group, lacrimal gland cytosolic vesicular density and size exceeded that in the SCOP group. ICES and SCOP induced murine dry eye effects became progressively more severe over a two week period. Subsequently, the disease process stabilized for the next four weeks. ICES induced local effects in the ocular surface, but failed to elicit lacrimal gland inflammation and cytoarchitectural changes, which accounts for less dry eye severity in the ICES model than that in the SCOP model.

Topical cyclosporine A in the treatment of dry eye: a systematic review and meta-analysis

PURPOSE

Cyclosporine A (CsA) is considered a potentially effective treatment for dry eye syndrome (DES), which is now one of the most common ocular problems whose exact mechanism is unknown. Because randomized controlled trials (RCTs) reported to date have shown varying results in the efficacy and safety of CsA in different types of DES, we conducted a systematic review and meta-analysis of RCTs on CsA versus placebo in treating DES to evaluate the treatment efficacy and safety of CsA.

METHODS

We searched for RCTs published after 1990, in MEDLINE, EMBASE, the Cochrane library, and ClinicalTrials.gov. The RCTs that were included compared topical CsA and placebo for DES treatment by evaluating scores of ocular surface disease index, tear break-up time, or Schirmer test. Cochrane risk of bias tool was used for assessing the risk of bias.

RESULTS

We included 12 RCTs involving 3034 eyes of 1660 participants. We observed statistically significant improvements on scores of break-up time (standardized mean difference [SMD], 0.80; 95% confidence interval [CI], 0.13-1.46; I = 95%) and scores of Schirmer test with anesthesia (SMD, 0.78; 95% CI, 0.09-1.46; I = 97%) after treatment with topical CsA. Scores of ocular surface disease index (SMD, 0.77; 95% CI, -1.05 to 2.58; I = 98%) and scores of Schirmer test without anesthesia (SMD, 0.08; 95% CI, -0.11 to 0.27; I = 0%) were not improved. Adverse events (odds ratio [OR], 1.61; 95% CI, 1.28-2.02; I = 21%) were observed.

CONCLUSIONS

Topical CsA could be an effective treatment for DES, especially for DES associated with conjunctival injury. Further RCTs with larger sample sizes for different clinical types of DES are warranted to determine the efficacy and limitation for different clinical types of DES.

[Ocular surface system integrity]

The interplay of different structures belonging to either the anterior segment of the eye or its accessory visual apparatus, which all share common embryological, anatomical, functional, and physiological features, is discussed. Explanation of such terms, as ocular surface, lacrimal functional unit, and ocular surface system, is provided.