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

Mucin deficiency causes functional and structural changes of the ocular surface

MUC5AC is the most abundant gel-forming mucin in the ocular system. However, the specific function is unknown. In the present study, a Muc5ac knockout (KO) mouse model was subject to various physiological measurements as compared to its wide-type (WT) control. Interestingly, when KO mice were compared to WT mice, the mean tear break up time (TBUT) values were significantly lower and corneal fluorescein staining scores were significantly higher. But the tear volume was not changed. Despite the lack of Muc5ac expression in the conjunctiva of KO mice, Muc5b expression was significantly increased in these mice. Corneal opacification, varying in location and severity, was found in a few KO mice but not in WT mice. The present results suggest a significant difference in the quality, but not the quantity, of tear fluid in the KO mice compared to WT mice. Dry eye disease is multifactorial and therefore further evaluation of the varying components of the tear film, lacrimal unit and corneal structure of these KO mice may help elucidate the role of mucins in dry eye disease. Because Muc5ac knockout mice have clinical features of dry eye, this mouse model will be extremely useful for further studies regarding the pathophysiology of the ocular surface in dry eye in humans.

PERSIST: Physician's Evaluation of Restasis(®) Satisfaction in Second Trial of topical cyclosporine ophthalmic emulsion 0.05% for dry eye: a retrospective review

Background

Chronic dry eye disease often requires long-term therapy. Tear film alterations in the setting of dry eye may include reduced tear volume as well as an increase in inflammatory cytokines and osmolarity. Topical cyclosporine ophthalmic emulsion 0.05% (Restasis^®; Allergan Inc, Irvine, CA) is indicated to increase tear production in patients with dry eye and reduced tear production presumed to be due to ocular inflammation. This study was designed to evaluate the efficacy of a second trial of topical cyclosporine in patients with dry eye who were previously considered treatment failures.

Materials and methods

This multicenter (three cornea practices) retrospective chart review evaluated clinical outcomes in patients with dry eye who received a second trial of cyclosporine after a prior treatment failure, defined as prior discontinuation of topical cyclosporine after less than 12 weeks.

Results

Thirty-five patients, most of whom were female (71.4%) and Caucasian (62.9%), were identified. Prior discontinuation was most commonly due to burning/stinging (60%). The median duration of second treatment was 10 months (range 1 week to 45 months). Physician education was provided in the second trial in 97.1% of cases. At initiation of the second trial of cyclosporine, 10 (28.6%) patients received courses of topical corticosteroids. Physicians reported on a questionnaire that 80% of patients achieved clinical benefit with a second trial of cyclosporine.

Conclusion

A repeat trial with topical cyclosporine can achieve clinical success. Direct patient education via the physician and staff may be key to success. Proper patient education may overcome adherence issues, particularly with respect to the need for long-term treatment of chronic dry eye. This study has the usual limitations associated with a retrospective chart review, and future prospective studies are warranted.

Comorbidities of dry eye disease: a nationwide population-based study

PURPOSE

To investigate the comorbidities of dry eye disease in a nationwide population-based data in Taiwan.

METHODS

This study features a study group and a comparison group. The study group comprised 12 007 patients who sought ambulatory care for treatment of dry eye in 2005 and 2006. In total, 36 021 randomly selected patients were in the comparison group. Conditional logistic regression analyses conditioned on gender, age, monthly income and level of urbanization of the community in which the patient resided were conducted to calculate the odds ratio (OR) for each of 33 comorbidities among patients with and without dry eye disease.

RESULTS

The regression analyses revealed that compared to patients without dry eye disease, patients with dry eye disease were more likely to have comorbidities of ischaemic heart disease (OR = 1.36), hyperlipidaemia (OR = 1.68), cardiac arrhythmias (OR = 1.55), peripheral vascular disorders (OR = 1.57), stroke (OR = 1.31), migraines (OR = 1.76), myasthenia gravis (OR = 2.85), RA (OR = 2.86), systemic lupus erythematosus (OR = 3.98), asthma (OR = 1.25), pulmonary circulation disorders (OR = 1.37), diabetes with complications (OR = 1.31), hypothyroidism (OR = 1.94), liver diseases (OR = 1.71), peptic ulcers (OR = 1.76), hepatitis B (OR = 1.64), deficiency anaemias (OR = 1.31), depression (OR = 2.11), psychoses (OR = 1.87) and solid tumours without metastasis (OR = 1.41).

CONCLUSIONS

This study demonstrates significantly higher prevalence of medical comorbidities in patients with dry eye disease in Taiwan.

Citation analysis of the dry eye literature

PURPOSE

The purpose of this study was to characterize the literature associated with the dry eye field.

METHODS

An advanced search using Thomson Reuters Web of Science's Science Citation Index yielded 7,225 unique articles related to dry eye disease. All results underwent visual inspection to ensure that the final list included only literature associated with dry eye in some way. The most frequently cited articles were characterized by number of citations, author, institution, country of origin, year of publication, and source title.

RESULTS

The h-index (Hirsch index) of literature associated with dry eye was 100. The two most frequent topics among the top 25 cited articles were lacrimal gland structure and physiology and treatment methods for ocular surface disease. The top-cited author, institution, country, and source title were Kazuo Tsubota, Harvard University, the United States, and Investigative Ophthalmology and Visual Science, respectively. The most highly cited article associated with the dry eye field (n=1, 180) was "Preliminary criteria for the classification of Sjogrens syndrome - Results of a prospective concerted action supported by the European Community," authored in 1993 by C. Vitali.

CONCLUSIONS

This analysis reviewed the citation frequency of the top-cited articles related to dry eye disease. This information aids understanding of the history and development of dry eye research, in addition to the impact and characteristics of the contributors to the field.

Tear analysis in ocular surface diseases

The thin layer of tears covering the ocular surface are a complex body fluid containing thousands of molecules of varied form and function of several origins. In this review, we have discussed some key issues in the analysis of tears in the context of understanding and diagnosing eye disease using current technologies of proteomics and metabolomics, and for their potential for clinical application. In the last several years, advances in proteomics/metabolomics/lipidomics technologies have greatly expanded our knowledge of the chemical composition of tear fluid. The quickened pace of studies has shown that tears as a complex extra-cellular fluid of the ocular surface contains a great deal of molecular information useful for the diagnosis, prognosis, and treatment of ocular surface diseases that has the ability to addresses the emphasis on personalized medicine and biomarkers of disease. Future research directions will likely include (1) standardize tear collection, storage, extraction, and sample preparation; (2) quantitative proteomic analysis of tear proteins using multiple reaction monitoring (MRM)-based mass spectrometry; (3) population based studies of human tear proteomics/metabolomics; (4) tear proteomics/metabolomics for systemic diseases; and (5) functional studies of tear proteins.

Spontaneous episodic decreased tear secretion in rats is related to opioidergic signaling pathways

PURPOSE

To elucidate the factors in tear production, this study examined the role of endogenous opioids and opioid receptors in spontaneous episodic reduced tear volume.

METHODS

A model of spontaneous episodic decreases in the quantity of tears was characterized in otherwise normal Sprague-Dawley rats using Schirmer's test. A single eye drop of 10(-5) M naltrexone (NTX), 10(-5) M [Met(5)]-enkephalin, or sterile vehicle was administered to one eye. Tear secretion, corneal sensitivity, and corneal morphology were examined in both eyes.

RESULTS

At any given time period, otherwise normal rats were found to have Schirmer test scores with a bimodal distribution (6.5 mm or less, or 7.0 mm or greater). Decreased tear production was detected in male and female rats aged 4 to 24 weeks at least once per animal. The episodes of reduced tear volume ranged from 1 to 7 days. No changes in corneal sensitivity or corneal morphology were observed in any rat. One drop of NTX given to rats with a decrease in tear volume raised levels of tears to scores of 7.0 mm or greater within 1 hour, and increased tear production persisted for at least 48 hours. NTX had no effect on rats with Schirmer scores of 7.0 mm or higher. Topical application of [Met(5)]-enkephalin depressed tear secretion from baseline scores of 9.8 ± 0.6 mm to as low as 4.5 ± 0.7 mm.

CONCLUSIONS

Normal rats experience fluctuations in tear production that can be modulated by opioidergic signaling pathways.

An overview on dry eye treatment: approaches for cyclosporin a delivery

Dry eye syndrome (DES, Keratoconjunctivitis sicca) is a common disorder of the tear film caused by decreased tear production or increased evaporation. Changes in tear composition also promote inflammation on the ocular surface by various mechanisms. Artificial tear drops, tear retention treatment, stimulation of tear secretion, or anti-inflammatory drugs may be used for dry eye treatment according to the severity of the disease. For untreated patients, the risk of ocular infection increases at considerable level and clinical course of the disease may proceed up to infection, corneal ulcer, and blindness. Artificial tears and/or punctual occlusions are used for tear replacement or preservation. New treatment approaches are designed to modify the underlying disease process. For the treatment of severe dry eye disease, cyclosporin A (CsA), the first one of the new generation immunomodulatory drugs, which has an anti-inflammatory effect, is frequently used. CsA has immunosuppressive effects following systemic application. Following local administration of CsA, it is expected to obtain effective drug concentration at the target area and to avoid the various side effects associated with systemic delivery. Microspheres, implants, and liposomes have been developed for administration of CsA subconjunctivally in order to enhance its efficiency.

Effect of airflow exposure on the tear meniscus

Purpose. To compare the effect of airflow exposure on the tear meniscus and blink frequency in normal and evaporative dry eye subjects. Methods. In 9 normal subjects and 9 short tear breakup time (SBUT) dry eye subjects, lower tear meniscus height (TMH) and area (TMA) and blink frequency were measured with anterior segment optical coherence tomography (OCT) before and after 5 minutes of airflow exposure (1.5 ± 0.5 m/s). Results. In SBUT dry eyes, both TMH and TMA decreased significantly (P = 0.027, P = 0.027) with a significant increase of blink frequency after airflow exposure, while significant increase in TMA was found in normal eyes. Conclusion. Measurement of the tear meniscus with anterior segment OCT seems to be useful as a noninvasive and objective method for evaluating the effect of airflow on tear film.

A Clinical Study of Acupuncture and SSP (Silver Spike Point) Electro-therapy for Dry Eye Syndrome

The present study was designed as a clinical trial to assess the efficacy of acupuncture and silver spike point (SSP) electro-therapy on dry eye syndrome. A total of 43 dry eye syndrome patients participated in the present study. Subjects were divided into control, acupuncture and SSP electro-therapy groups. The three groups were all given artificial tears treatment. Patients in the treatment groups were given two 20-minute treatments of either acupuncture or SSP. Assessment was carried out using the Basal Schirmer test, tear break-up time (BUT), visual analog scale (VAS) and an overall score of eye condition. After four weeks of treatment, both the acupuncture and SSP treatment groups showed improvements over the control group, in Schirmer tests of the left eye and average tearing of both eyes. After 8 weeks of treatment, both treatment groups showed improvements over the control group both in Schirmer tests and VAS. For the right eye, treatment groups showed significant improvements in Schirmer test and VAS versus the control group averages for both eyes. There was no significant difference in BUT at any time. Comparing scores before and after treatment, the acupuncture and SSP groups showed a significant improvement compared to the control group. The acupuncture group showed a greater 8-week improvement in Schirmer tests scores compared to the SSP group. However, the SSP group patients used fewer applications of artificial tears. Acupuncture and SSP electro-therapy were effective in increasing tear secretion in patients with dry eye syndrome. The SSP electro-therapy not only alleviated dry eye syndrome, but also reduced the number of applications of artificial tears necessary.

Ocular surface immunity: homeostatic mechanisms and their disruption in dry eye disease

The tear film, lacrimal glands, corneal and conjunctival epithelia and Meibomian glands work together as a lacrimal functional unit (LFU) to preserve the integrity and function of the ocular surface. The integrity of this unit is necessary for the health and normal function of the eye and visual system. Nervous connections and systemic hormones are well known factors that maintain the homeostasis of the ocular surface. They control the response to internal and external stimuli. Our and others' studies show that immunological mechanisms also play a pivotal role in regulating the ocular surface environment. Our studies demonstrate how anti-inflammatory factors such as the expression of vascular endothelial growth factor receptor-3 (VEGFR-3) in corneal cells, immature corneal resident antigen-presenting cells, and regulatory T cells play an active role in protecting the ocular surface. Dry eye disease (DED) affects millions of people worldwide and negatively influences the quality of life for patients. In its most severe forms, DED may lead to blindness. The etiology and pathogenesis of DED remain largely unclear. Nonetheless, in this review we summarize the role of the disruption of afferent and efferent immunoregulatory mechanisms that are responsible for the chronicity of the disease, its symptoms, and its clinical signs. We illustrate current anti-inflammatory treatments for DED and propose that prevention of the disruption of immunoregulatory mechanisms may represent a promising therapeutic strategy towards controlling ocular surface inflammation.

Tear dysfunction and the cornea: LXVIII Edward Jackson Memorial Lecture

PURPOSE

To describe the cause and consequence of tear dysfunction-related corneal disease.

DESIGN

Perspective on effects of tear dysfunction on the cornea.

METHODS

Evidence is presented on the effects of tear dysfunction on corneal morphology, function, and health, as well as efficacy of therapies for tear dysfunction-related corneal disease.

RESULTS

Tear dysfunction is a prevalent eye disease and the most frequent cause for superficial corneal epithelial disease that results in corneal barrier disruption, an irregular optical surface, light scattering, optical aberrations, and exposure and sensitization of pain-sensing nerve endings (nociceptors). Tear dysfunction-related corneal disease causes irritation and visual symptoms such as photophobia and blurred and fluctuating vision that may decrease quality of life. Dysfunction of 1 or more components of the lacrimal functional unit results in changes in tear composition, including elevated osmolarity and increased concentrations of matrix metalloproteinases, inflammatory cytokines, and chemokines. These tear compositional changes promote disruption of tight junctions, alter differentiation, and accelerate death of corneal epithelial cells.

CONCLUSIONS

Corneal epithelial disease resulting from tear dysfunction causes eye irritation and decreases visual function. Clinical and basic research has improved understanding of the pathogenesis of tear dysfunction-related corneal epithelial disease, as well as treatment outcomes.

Detection of BrdU-label retaining cells in the lacrimal gland: implications for tissue repair

The purpose of the present study was to determine if the lacrimal gland contains 5-bromo-2'-deoxyuridine (BrdU)-label retaining cells and if they are involved in tissue repair. Animals were pulsed daily with BrdU injections for 7 consecutive days. After a chase period of 2, 4, or 12 weeks, the animals were sacrificed and the lacrimal glands were removed and processed for BrdU immunostaining. In another series of experiments, the lacrimal glands of 12-week chased animals were either left untreated or were injected with interleukin 1 (IL-1) to induce injury. Two and half days post-injection, the lacrimal glands were removed and processed for BrdU immunostaining. After 2 and 4 weeks of chase period, a substantial number of lacrimal gland cells were BrdU(+) (11.98 ± 1.84 and 7.95 ± 1.83 BrdU(+) cells/mm(2), respectively). After 12 weeks of chase, there was a 97% decline in the number of BrdU(+) cells (0.38 ± 0.06 BrdU(+) cells/mm(2)), suggesting that these BrdU-label retaining cells may represent slow-cycling adult stem/progenitor cells. In support of this hypothesis, the number of BrdU labeled cells increased over 7-fold during repair of the lacrimal gland (control: 0.41 ± 0.09 BrdU(+) cells/mm(2); injured: 2.91 ± 0.62 BrdU(+) cells/mm(2)). Furthermore, during repair, among BrdU(+) cells 58.2 ± 3.6 % were acinar cells, 26.4 ± 4.1% were myoepithelial cells, 0.4 ± 0.4% were ductal cells and 15.0 ± 3.0% were stromal cells. We conclude that the murine lacrimal gland contains BrdU-label retaining cells that are mobilized following injury to generate acinar, myoepithelial and ductal cells.

Reversibility of dry eye deceleration after topical cyclosporine 0.05% withdrawal

PURPOSE

To assess the reversibility of clinical benefits of cyclosporine 0.05% (Restasis(®); Allergan, Inc., Irvine, CA) therapy and the therapeutic gain after its delayed use by switching treatment modalities in patients with dry eyes who completed a 1-year course of therapy with artificial tears (Refresh Endura(®); Allergan, Inc., Irvine, CA) or cyclosporine 0.05%.

METHODS

This was a single-center, prospective, investigator-masked, longitudinal extension trial. Patients who had been treated with cyclosporine 0.05% in the first year of study were randomized in a 2:1 ratio to either cyclosporine 0.05% (Cs-Cs; n=20) or artificial tears (Cs-At; n=8), and those who had been originally randomized to artificial tears were switched to cyclosporine 0.05% (At-Cs; n=20) in the second year of study. Patients received study drugs twice daily for 12 months. Disease severity was assessed according to the International Task Force consensus guideline at months 0 and 12. Signs and symptoms were evaluated at baseline (month 0) and months 4, 8, and 12.

RESULTS

At baseline, most patients with Cs-Cs and Cs-At (>90%) had level 2 disease severity, whereas almost half of the patients with At-Cs had level 3 disease severity. At month 12, a significantly higher percentage of patients with Cs-Cs and At-Cs than patients with Cs-At had the same or lower disease severity (P<0.001); whereas half of patients with Cs-At, compared with patients with no Cs-Cs and At-Cs, had disease progression at month 12. Throughout the study, dry eye signs and symptoms continuously improved in patients with Cs-Cs and At-Cs, whereas they constantly worsened in patients with Cs-At. At month 12, patients with Cs-Cs and At-Cs had significantly greater mean percentage improvement from baseline than did patients with Cs-At in Schirmer test scores, tear breakup time, Oxford staining scores, Ocular Surface Disease Index scores, and conjunctival goblet cell density (P<0.001). Overall, sign and symptom scores of patients with At-Cs did not improve as much as they did for patients with Cs-Cs.

CONCLUSIONS

Cyclosporine 0.05% withdrawal led to disease progression, thus indicating the necessity for maintenance therapy. Earlier treatment with cyclosporine 0.05% may result in improved outcomes.

Corneal hysteresis in patients with dry eye

PURPOSE

To measure corneal hysteresis and intraocular pressure (IOP) in patients with dry eye and to compare with normal subjects.

METHODS

This cross-sectional study consists of 70 eyes of 40 patients with dry eye (group 1) and 75 eyes of 40 normal subjects (group 2). Eyes were diagnosed as dry eye or normal according to the clinical symptoms, biomicroscopical evaluation, and Schirmer test. Corneal hysteresis (CH), corneal resistance factor (CRF), and cornea-compensated intraocular pressure (IOPcc) were measured by the Ocular Response Analyser (ORA).

RESULTS

Mean CH values were 10.56±0.25 mm Hg and 10.34±0.26 mm Hg, mean CRF values were 10.75±0.28 mm Hg and 10.70±0.28 mm Hg, mean CCT values were 542±3.20 μm and 543±3.89 μm in group 1 and group 2, respectively. There was no statistically significant difference between the groups for these three parameters. IOPcc values measured with ORA were 15.73±0.36 mm Hg in group 1 and 16.60±0.33 mm Hg in group 2, and there was no statistically significant difference between the two groups.

CONCLUSIONS

Corneal biomechanical parameters such as CH and CRF are not influenced in dry eye. Also statistical difference was not found between the two groups according to CCT and IOPcc values.

Interferon-γ exacerbates dry eye-induced apoptosis in conjunctiva through dual apoptotic pathways

PURPOSE

To investigate the role of interferon (IFN)-γ in dry eye-associated conjunctival apoptosis.

METHODS

Desiccating stress (DS) was created in C57BL/6 (B6) and C57BL/6 IFN-γ-knockout (B6γKO) mice. A separate group of mice of both strains also received subconjunctival injections of exogenous IFN-γ or vehicle control (BSA) at days 0, +2, and +4 after DS. Immunoreactivity to active (Ac)-caspase-3, -8, and -9 and terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) were evaluated in cryosections. Goblet cell apoptosis was assessed by MUC5AC and TUNEL double staining. Levels of caspase-3, -8, -9, Fas, and Fas-associated protein with Death Domain (FADD) mRNA in conjunctiva were measured by real-time PCR. The activity of caspase-3, -8, or -9 was measured using fluorometric assay.

RESULTS

Increased Ac-caspase-3 and -8 and TUNEL immunoreactivity were noted in conjunctival epithelia in B6 mice compared with B6γKO mice after DS, and exogenous IFN-γ administration further increased these parameters. DS-induced conjunctival apoptosis was greatest in the goblet cell area and was accompanied by a decrease in MUC5AC expression in the B6 and B6-IFN-γ-injected groups compared with the B6γKO and B6-BSA-injected groups. B6γKO mice were resistant to DS-induced apoptosis; however, B6γKO receiving IFN-γ yielded results similar to those for B6 wild-type. Caspase-9 production and activity were not increased with DS in B6 or B6γKO mice; however, the administration of IFN-γ significantly increased caspase-9 production and activity in both strains compared with vehicle-injected mice.

CONCLUSIONS

IFN-γ plays a pivotal role in exacerbating conjunctival apoptosis through dual apoptotic pathways with DS.

Treatment of chronic dry eye: focus on cyclosporine

To review the current treatment of chronic dry eye syndrome, focusing on cyclosporine A (CsA), a systematic literature search was performed using PubMed databases in two steps. The first step was oriented to articles published for dry eye. The second step was focused on the use of CsA in dry eye. A manual literature search was also undertaken based on citations in the published articles. The knowledge on the pathogenesis of dry eye syndrome has changed dramatically during the last few years. Inflammation and the interruption of the inflammatory cascade seem to be the main focus of the ophthalmologic community in the treatment of dry eye, giving the anti-inflammatory therapy a new critical role. The infiltration of T-cells in the conjuctiva tissue and the presence of cytokines and proteasis in the tear fluid were the main reason introducing the use of immunomodulator agents such as corticosteroids, cyclosporine, and doxycicline in order to treat dry eye syndrome. CsA emulsion is approved by the FDA for the treatment of dry eye, while clinical trials of this agent have demonstrated efficacy and safety of CsA. CsA seems to be a promising treatment against dry eye disease. New agents focused on the inflammatory pathogenesis of this syndrome in combination with CsA may be the future in the quest of treating dry eye. More studies are needed to determine the efficacy, safety, timing, and relative cost/effect of CsA.

A randomized clinical evaluation of the safety of Systane Lubricant Eye Drops for the relief of dry eye symptoms following LASIK refractive surgery

Purpose

To evaluate the safety of Systane^® Lubricant Eye Drops in relieving the symptoms of dry eye following laser-assisted in situ keratomileusis (LASIK) surgery.

Methods

This was a randomized, double-masked, single-center, placebo-controlled, contralateral eye study of 30 patients undergoing LASIK surgery. The mean age of patients was 42.4 ± 10.7 years, and the mean spherical equivalent was −3.29 (range, +1.75 to −7.38). Patients’ right and left eyes were randomized to receive either Systane^® or placebo – a preserved, thimerosal-free saline solution – beginning from the day of surgery and ending 30 days following surgery. Outcome measures included tear film break up time (TFBUT), visual acuity, degree of corneal and conjunctival staining, and treatment-related adverse events.

Results

Preoperatively, placebo-treated eyes had statistically significantly higher sum corneal staining score than Systane^®-treated eyes (p = 0.0464); however, the difference was clinically insignificant (p = 0.27). Two weeks post operatively, the average TFBUT in the Systane^®-treated eyes was 1.23 seconds longer than that of the placebo-treated eyes (p = 0.028). All other evaluated variables were comparable between the two treatments. No adverse events were reported in the study.

Conclusion

Systane^® Lubricant Eye Drops are safe for use following LASIK surgery to relieve the discomfort symptoms of dry eye associated with the procedure.

Inflammation and the nervous system: the connection in the cornea in patients with infectious keratitis

PURPOSE

To study the density and morphologic characteristics of epithelial dendritic cells, as correlated to subbasal corneal nerve alterations in acute infectious keratitis (IK) by in vivo confocal microscopy (IVCM).

METHODS

IVCM of the central cornea was performed prospectively in 53 eyes with acute bacterial (n = 23), fungal (n = 13), and Acanthamoeba (n = 17) keratitis, and in 20 normal eyes, by using laser in vivo confocal microscopy. Density and morphology of dendritic-shaped cells (DCs) of the central cornea, corneal nerve density, nerve numbers, branching, and tortuosity were assessed and correlated. It should be noted that due to the "in vivo" nature of the study, the exact identity of these DCs cannot be specified, as they could be monocytes or tissue macrophages, but most likely dendritic cells.

RESULTS

IVCM revealed the presence of central corneal DCs in all patients and controls. The mean DC density was significantly higher in patients with bacterial (441.1 ± 320.5 cells/mm(2); P < 0.0001), fungal (608.9 ± 812.5 cells/mm(2); P < 0.0001), and Acanthamoeba keratitis (1000.2 ± 1090.3 cells/mm(2); P < 0.0001) compared with controls (49.3 ± 39.6 cells/mm(2)). DCs had an increased size and dendrites in patients with IK. Corneal nerves were significantly reduced in eyes with IK compared with controls across all subgroups, including nerve density (674.2 ± 976.1 vs. 3913.9 ± 507.4 μm/frame), total nerve numbers (2.7 ± 3.9 vs. 20.2 ± 3.3), main trunks (1.5 ± 2.2 vs. 6.9 ± 1.1), and branching (1.2 ± 2.0 vs. 13.5 ± 3.1; P < 0.0001). A strong association between the diminishment of corneal nerves and the increase of DC density was observed (r = -0.44; P < 0.0005).

CONCLUSIONS

IVCM reveals an increased density and morphologic changes of central epithelial DCs in infectious keratitis. There is a strong and significant correlation between the increase in DC numbers and the decreased subbasal corneal nerves, suggesting a potential interaction between the immune and nervous system in the cornea.

Tear analysis and lens-tear interactions: part II. Ocular lipids-nature and fate of meibomian gland phospholipids

PURPOSE

Published data indicate that the polar lipid content of human meibomian gland secretions (MGS) could be anything between 0.5% and 13% of the total lipid. The tear film phospholipid composition has not been studied in great detail and it has been understood that the relative proportions of lipids in MGS would be maintained in the tear film. The purpose of this work was to determine the concentration of phospholipids in the human tear film.

METHODS

Liquid chromatography mass spectrometry (LCMS) and thin layer chromatography (TLC) were used to determine the concentration of phospholipid in the tear film. Additionally, an Amplex Red phosphatidylcholine-specific phospholipase C (PLC) assay kit was used for determination of the activity of PLC in the tear film.

RESULTS

Phospholipids were not detected in any of the tested human tear samples with the low limit of detection being 1.3 μg/mL for TLC and 4 μg/mL for liquid chromatography mass spectrometry. TLC indicated that diacylglycerol (DAG) may be present in the tear film. PLC was in the tear film with an activity determined at approximately 15 mU/mL, equivalent to the removal of head groups from phosphatidylcholine at a rate of approximately 15 μM/min.

CONCLUSIONS

This work shows that phospholipid was not detected in any of the tested human tear samples (above the lower limits of detection as described) and suggests the presence of DAG in the tear film. DAG is known to be at low concentrations in MGS. These observations indicate that PLC may play a role in modulating the tear film phospholipid concentration.

Resolvin E1 improves tear production and decreases inflammation in a dry eye mouse model

PURPOSE

Dry eye (DE) is a common ocular surface disease, particularly among women and the elderly, with chronic symptoms of eye irritation and, in severe cases, blurred vision. Several studies have shown that there is an inflammatory component in DE, although the pathogenesis is not thoroughly understood. Resolvin E1 (RvE1; RX-10001) is an endogenous mediator derived from the omega-3 polyunsaturated fatty acid eicosapentaenoic acid and is involved in inflammation resolution and tissue protection. Here we investigated the role of RvE1 in a DE mouse model.

METHODS

Thirteen- to 14-week-old female BALB/C mice were exposed to desiccating conditions. One week after DE exposure, animals were treated topically with drug or vehicle 4 times per day for an additional week. Controls were nontreated animals placed in a normal environment. Schirmer's test was performed before treatment initiation and at days 2 and 4 after treatment. Density of corneal epithelial cells was analyzed in vivo using the Rostock Cornea Module of the Heidelberg Retina Tomograph (HRT-II). Corneas were processed using Western blot analysis and immunofluorescence examination.

RESULTS

Schirmer's test showed a significant decrease in tear production in DE compared with controls. There was no change at 2 and 4 days after treatment with the vehicle, but a significant increase was observed at 2 and 4 days in the RvE1-treated group. The density of the superficial epithelial cells showed a significant decrease after DE compared with controls, which increased after 7 days of RvE1 treatment. Western blot analysis showed that α-smooth muscle actin and cyclooxygenase-2 (COX-2) expression were strongly upregulated after DE and decreased after 7 days of RvE1 treatment. Immunofluorescence confirmed strong positive staining of α-smooth muscle actin and COX-2 in stroma and/or in epithelia after DE, which decreased with RvE1 treatment. The percentage of infiltrating CD⁴+ T cells and CD11b+ cells decreased after RvE1 treatment when compared with DE.

CONCLUSION

RvE1 promotes tear production, corneal epithelial integrity, and a decrease in inflammatory inducible COX-2. In the stroma, RvE1 inhibits keratocyte transformation to myofibroblasts and lowers the number of monocytes/macrophages in this DE mouse model. These results suggest that RvE1 and similar resolvin analogs have therapeutic potential in the treatment of DE.

An investigation of the efficacy of a novel ocular lubricant

OBJECTIVE

To investigate the efficacy of a novel ocular lubricant compared with a commercially marketed ocular lubricant in a group of noncontact lens wearers currently using over-the-counter products for the management of symptoms of moderate to severe dry eye.

METHODS

This was a prospective, double-masked study that randomized 110 subjects in a ratio of 1:1 to receive a novel ocular lubricant (test group) or a marketed ocular lubricant (control group). Subjects were instructed to instill the lubricant eye drops at least three times daily. After enrollment, subjects were evaluated at baseline and at 7 and 30 days. They were also required to complete a series of home-based subjective questionnaires after 15 days. Main outcomes were subjective symptoms and objective clinical assessment at 7 and 30 days.

RESULTS

The test group had higher overall comfort ratings than the control group (P = 0.012). Seventy-one percent of the test group and 57% of the control group said the drops used "somewhat" or "definitely" improved ocular comfort; 62% of the test group had greater end-of-day comfort compared with 45% of the control group (P = 0.015). There were no between-group differences in visual acuity, tear quality or quantity, corneal staining, conjunctival staining, or bulbar and limbal conjunctival hyperemia.

CONCLUSIONS

The novel ocular lubricant offers equivalent or superior comfort compared with a marketed lubricant eye drop. Objective clinical outcomes were not statistically significantly different between the two groups.

Association between unilateral quiescent stromal herpetic keratitis and bilateral dry eyes

PURPOSE

According to our clinical observation, patients with quiescent herpes simplex virus (HSV) stromal keratitis often seem to present with signs of dry eye in the contralateral eye. Our goal was to compare dry eye signs and symptoms in both eyes of patients with quiescent HSV stromal keratitis with those of age- and sex-matched control subjects with healthy corneas.

METHODS

A case-control study with 24 subjects per group.

RESULTS

The average age of 10 men and 14 women in each group was 58 years. The HSV eye of cases was first compared with the contralateral eye with a healthy cornea. As expected, the HSV eye had a significantly lower corneal sensation threshold (P = 0.001); no significant difference was however found for Schirmer tests done with anesthesia (basal tear secretion) and without anesthesia, tear breakup time, mucus and debris in the tear film, and eyelid margin redness or swelling. Then, the HSV eye of cases was compared with the right eye of controls, whereas the healthy eye of cases was compared with the left eye of controls. Patients with unilateral quiescent HSV stromal keratitis had significantly lower bilateral Schirmer tests both with anesthesia (P = 0.001) and without anesthesia (P = 0.02). Dry eye symptoms of the healthy cornea of cases and those of controls did not differ significantly.

CONCLUSIONS

Both eyes of patients with quiescent HSV stromal keratitis in our population were dry even if many patients with HSV stromal keratitis did not have symptoms in their fellow eye.

Dry eye disease as an inflammatory disorder

PURPOSE

Dry eye disease (DED) is a prevalent inflammatory disorder of the lacrimal functional unit of multifactorial origin leading to chronic ocular surface disease, impaired quality of vision, and a wide range of complications, eventually causing a reduction in quality of life. It still is a frustrating disease because of the present scarcity of therapies that can reverse, or at least stop, its progression.

METHODS

A comprehensive literature survey of English-written scientific publications on the role of inflammation in DED.

RESULTS

New investigations have demonstrated that a chronic inflammatory response plays a key role in the pathogenesis of human DED. Additionally, correlations between inflammatory molecules and clinical data suggest that inflammation can be responsible for some of the clinical symptoms and signs.

CONCLUSIONS

Research efforts to clarify its pathophysiology are leading to a better understanding of DED, demonstrating that inflammation, in addition to many other factors, plays a relevant role.

A comparison of cyclosporine 0.05% ophthalmic emulsion versus vehicle in Chinese patients with moderate to severe dry eye disease: an eight-week, multicenter, randomized, double-blind, parallel-group trial

PURPOSE

The goals of this study were to compare the efficacy and safety profile of topical cyclosporine 0.05% versus vehicle in Chinese patients with moderate to severe dry eye disease.

METHODS

In this multicenter, randomized, double-blind, vehicle-controlled, parallel-group study, 233 dry eye patients were allocated to receive either cyclosporine 0.05% or vehicle twice daily for 8 weeks. Primary outcome was the difference between groups, in total score of 4 symptoms and 4 signs change from baseline at weeks 2, 4, and 8. Changes in symptoms (ocular dryness, foreign body sensation, photophobia and burning) and signs (conjunctival hyperemia, Schirmer test, tear Break-up time (BUT), and corneal punctate fluorescein staining) at weeks 2, 4, and 8 as well as frequency of administration of concomitant artificial tears, were considered as secondary outcomes. The safety profile was evaluated by examining adverse events, changes in visual acuity, and ocular tolerance.

RESULTS

Greater improvements of the total score were seen in cyclosporine 0.05% group than in the vehicle group at all follow-up times (P < 0.01). Improvements in ocular dryness at week 8 (P = 0.040) and foreign body sensation during weeks 4 and 8 (P < 0.020) were significantly greater with cyclosporine. In addition, compared with the vehicle, cyclosporine significantly improved 2 objective dry eye disease signs: corneal staining at weeks 4 (P = 0.025) and 8 (P = 0.050) and the Schirmer test at week 4 (P = 0.035). However, no between-group difference approached statistical significance in photophobia, burning, BUT value, conjunctival hyperemia and frequency of administration of concomitant artificial tears at any follow-up times (P > 0.05).The cumulative frequency of adverse events did not significantly differ between the groups (P = 0.519), which were 11.21% and 8.55%, respectively. There were no patients who experienced reduced visual acuity.

CONCLUSION

Cyclosporine 0.05% ophthalmic emulsion is an effective and safe treatment for Chinese patients with moderate to severe dry eye disease.

Pharmacotherapy of dry eye

INTRODUCTION

based on data from the largest studies of dry eye to date - the Women's Health Study (WHS) and the Physicians' Health Study (PHS) - and other studies, it has been estimated that about 3.23 million women and 1.68 million men, for a total of 4.91 million Americans aged ≥ 50 years, have dry eye. Tens of millions more have less severe symptoms and probably a more episodic manifestation of the disease that is notable only during contact with some adverse contributing factor(s), such as low humidity or contact lens wear. Dry eye disease is a common yet frequently under-recognized public health problem whose etiology and management challenge clinicians and researchers involved in this field.

AREAS COVERED

advances in the understanding of the disease have been made over the past 10 years in areas of epidemiology, pathogenesis, clinical manifestation, and possible therapy. Historical aspects and recent information in relation to the use of artificial tear substitutes and anti-inflammatory agents in dry eye disease, including topical cyclosporin and corticosteroids, autologous serum, tetracyclines and systemic immunosuppressants, are covered in this review. The reader will gain insight into the recent views on the pharmacological menu of treatments for dry eyes following the recommendations of the 2007 International Dry Eye Workshop.

EXPERT OPINION

dry eye is a visually disabling disease, the treatment of which needs tailoring according to the type and severity of dry eye disease.

Topical loteprednol pretreatment reduces cyclosporine stinging in chronic dry eye disease

PURPOSE

This retrospective, clinical comparative analysis describes differences in clinical signs and symptoms and medication tolerability between those patients who receive topical corticosteroids prior to initiation of topical cyclosporine 0.5% emulsion (tCSA) therapy for chronic dry eye disease (CDED) and those who received tCSA and were not first induced with corticosteroid drops. tCSA is the only approved medication for CDED. Stinging is the most common side effect of tCSA and reason for tCSA discontinuation. This analysis describes an effective pharmacologic means to reduce tCSA stinging and subsequent discontinuation.

METHODS

Thirty-six consecutive patients were initially treated with loteprednol etabonate (LE) 0.5% (Lotemax; Bausch & Lomb) for a period ranging from 2 to 16 months prior to institution of concomitant tCSA (Restasis™; Allergan). Clinical parameters (fluorescein staining, conjunctival redness, tear meniscus) were compared over a period of 6 months to a second cohort of 36 consecutive patients who were initially prescribed continuous tCSA without concomitant LE pretreatment. Patients in the LE pretreatment group discontinued LE after 3-6 months of concomitant therapy while continuing tCSA therapy.

RESULTS

Of the 36 LE pretreatment patients, only 2 developed significant stinging (5.5%) and 1 discontinued the use of tCSA because of stinging (2.8%). Of the patients without LE pretreatment, 8 developed stinging (22%) and 3 discontinued tCSA as a result (8.3%). The intergroup P value was significant for severe stinging (<0.02) and for tCSA discontinuation because of severe stinging (<0.04). Patients in the LE pretreatment group had no statistically significant differences in preenrollment disease severity or demographics (P range from 0.19 to 0.59) compared with the group without pretreatment.

CONCLUSION

Topical corticosteroid preparation of the ocular surface in CDED with LE induction therapy may reduce discomfort from subsequent long-term maintenance topical medications, particularly tCSA. This analysis describes a readily available induction and maintenance pharmacologic strategy to reduce tCSA stinging and subsequent discontinuation.

Cytokine and chemokine levels in tears from healthy subjects

PURPOSE

There is growing evidence for the existence of an 'immune tone' in normal tears. The aim of this study was to determine the levels of a large panel of cytokines and chemokines in tears obtained from healthy subjects. These levels can then serve as baseline values for comparison with patients suffering from ocular surface diseases.

SUBJECTS AND METHODS

Nine healthy subjects participated in this study, and normal ocular surface health was documented by the results of a dry eye questionnaire, Schirmer strip wetting, and vital staining of the cornea. Four microliters of tears were collected from each eye and analysed separately with multiplex bead-based assays for the concentration of 30 cytokines and chemokines.

RESULTS

Twenty-five cytokines/chemokines were detected. CCL11/Eotaxin1, GM-CSF, G-CSF, IFN-γ, IL-2, IL-3, IL-4, IL-5, IL-10, IL-13, IL-12p70, IL-15, CX3CL1/Fractalkine, TNF-α, epidermal growth factor, and CCL4/MIP-1β were present at 5-100 pg/ml. IL-1β, IL-6, IL-7A, CXCL8/IL-8, and CCL2/MCP-1 were present at 100-400 pg/ml. IL-1Ra, CXCL10/IP-10 and vascular endothelial growth factor were present at more than 1000 pg/ml.

CONCLUSION

Multiplex bead-based assays are convenient for cytokine/chemokine detection in tears. Fracktalkine has been detected in human healthy tears for the first time. The knowledge of cytokine/chemokine concentrations in tears from normal subjects is an important reference for further comparison with patients suffering from ocular surface diseases. Variability in their levels can reflect a phenomenon of potential importance for the understanding of the ocular surface cytokine pattern.

Altered morphology and function of the lacrimal functional unit in protein kinase C{alpha} knockout mice

PURPOSE

Protein kinase C (PKC) α plays a major role in the parasympathetic neural stimulation of lacrimal gland (LG) secretion. It also has been reported to have antiapoptotic properties and to promote cell survival. Therefore, the hypothesis for the present study was that PKCα knockout ((-/-)) mice have impaired ocular surface-lacrimal gland signaling, rendering them susceptible to desiccating stress and impaired corneal epithelial wound healing. In this study, the lacrimal function unit (LFU) and the stressed wound-healing response were examined in PKCα(-/-) mice.

METHODS

In PKCα(+/+) control mice and PKCα(-/-) mice, tear production, osmolarity, and clearance rate were evaluated before and after experimental desiccating stress. Histology and immunofluorescent staining of PKC and epidermal growth factor were performed in tissues of the LFU. Cornified envelope (CE) precursor protein expression and cell proliferation were evaluated. The time course of healing and degree of neutrophil infiltration was evaluated after corneal epithelial wounding.

RESULTS

Compared with the PKCα(+/+) mice, the PKCα(-/-) mice were noted to have significantly increased lacrimal gland weight, with enlarged, carbohydrate-rich, PAS-positive acinar cells; increased corneal epithelia permeability, with reduced CE expression; and larger conjunctival epithelial goblet cells. The PKCα(-/-) mice showed more rapid corneal epithelial healing, with less neutrophil infiltration and fewer proliferating cells than did the PKCα(+/+) mice.

CONCLUSIONS

The PKCα(-/-) mice showed lower tear production, which appeared to be caused by impaired secretion by the LG and conjunctival goblet cells. Despite their altered tear dynamics, the PKCα(-/-) mice demonstrated more rapid corneal epithelial wound healing, perhaps due to decreased neutrophil infiltration.

Dry eye disease

Dry eye (DED) is a multifactorial disease that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface, accompanied by increased osmolarity of the tear film and inflammation. DED is a common clinical problem and is among the most frequent diagnoses in ophthalmology. It substantially affects quality of life because of the constant ocular discomfort and decrease in visual function. This review discusses the etiology, classification, diagnosis procedures, clinical, and surgical treatments of dry eye.

Novel hydroxypropyl-guar gellable lubricant eye drops for treatment of dry eye

OBJECTIVE|: The objective of this review is to evaluate the safety and efficacy of polyethylene glycol 400/propylene glycol/hydroxypropyl-guar (Systane® Ultra [PEG/PG with HP-guar], Alcon Laboratories, Inc., Fort Worth, TX, USA) lubricant eye drops in reducing the signs and symptoms of dry-eye disease. METHODS|: A systematic literature search utilizing MEDLINE was conducted to identify peer-reviewed articles related to dry-eye disease and PEG/PG with HP-guar lubricant eye drops. The search covered the period prior to October 2009. Additionally, a manual search based on citations in the published literature was conducted. RESULTS|: The PEG/PG with HP-guar artificial tears shows in-vitro viscoelastic properties with pH optimization. The pH of the solution adjusts to the pH of the ocular surface upon instillation, which results in tear film elasticity and viscosity similar to that of subjects without dry-eye disease. The reviewed literature demonstrated that this delivery system showed a reduction in corneal and conjunctival staining in dryeye disease, an improvement in tear film stability, a low coefficient of friction in an in-vitro model, and improved maintenance of best-corrected visual acuity over time. CONCLUSION|: A few small-sized studies with short-term follow-up demonstrated that PEG/PG with HP-guar is a safe and effective lubricant eye drops for the treatment of dry-eye disease. Larger studies with longer duration are warranted to assess the long-term safety and efficacy of this formulation in patients with dry.eye disease.

Topical cyclosporine 0.05% for the prevention of dry eye disease progression

PURPOSE

To assess the prognosis of dry eye in patients treated with cyclosporine 0.05% or artificial tears by using the International Task Force (ITF) guidelines.

METHODS

This was a single-center, investigator-masked, prospective, randomized, longitudinal trial. Dry eye patients received twice-daily treatment with either cyclosporine 0.05% (Restasis; Allergan, Inc., Irvine, CA; n = 36) or artificial tears (Refresh Endura; Allergan, Inc., Irvine, CA; n = 22) for 12 months. Disease severity was determined at baseline and month 12 according to the consensus guidelines developed by the ITF. Dry eye signs and symptoms were evaluated at baseline and months 4, 8, and 12.

RESULTS

Baseline sign and symptom scores and the proportion of patients with the disease severity level 2 or 3 were comparable in both groups (P > 0.05). At month 12, 34 of 36 cyclosporine patients (94%) and 15 of 22 artificial tear patients (68%) experienced improvements or no change in their disease severity (P = 0.007) while 2 of 36 cyclosporine patients (6%) and 7 of 22 artificial tears patients (32%) had disease progression (P < 0.01). Cyclosporine 0.05% improved Schirmer test scores, tear breakup time, and Ocular Surface Disease Index scores throughout the study, with significant (P < 0.01) differences compared with artificial tears being observed at months 8 and 12.

CONCLUSIONS

Treatment with cyclosporine 0.05% may slow or prevent disease progression in patients with dry eye at severity levels 2 or 3.

In vivo confocal microscopy of corneal nerves: analysis and clinical correlation

Corneal confocal microscopy is a growing technique for the study of the cornea at the cellular level, providing images comparable to ex vivo histochemical methods. In vivo confocal microscopy (IVCM) has an enormous potential, being a noninvasive procedure that images the living cornea, to study both its physiological and pathological states. Corneal nerves are of great interest to clinicians and scientists due to their important roles in regulating corneal sensation, epithelial integrity, proliferation, wound healing, and for their protective functions. IVCM enables the noninvasive examination of corneal nerves, allowing the study of nerve alterations in different ocular diseases, after corneal surgery, and in systemic diseases. To date, the correlation of sub-basal corneal nerves and their function has been studied in normal eyes, keratoconus, dry eye, contact lens wearers, and in neurotrophic keratopathy, among others. Further, the effect of corneal surgery on nerves has been studied, demonstrating the regenerative capacity of corneal nerves and the recovery of sensation. Moreover, IVCM has been applied in the diagnosis of peripheral diabetic neuropathy and the assessment of progression in this systemic disease. The purpose of this review is to describe the principles, applications, and clinical correlation of IVCM in the study of corneal nerves in different ocular and systemic diseases.

Autoimmunity at the ocular surface: pathogenesis and regulation

A healthy ocular surface environment is essential to preserve visual function, and as such the eye has evolved a complex network of mechanisms to maintain homeostasis. Fundamental to the health of the ocular surface is the immune system, designed to respond rapidly to environmental and microbial insults, whereas maintaining tolerance to self-antigens and commensal microbes. To this end, activation of the innate and adaptive immune response is tightly regulated to limit bystander tissue damage. However, aberrant activation of the immune system can result in autoimmunity to self-antigens localized to the ocular surface and associated tissues. Environmental, microbial and endogenous stress, antigen localization, and genetic factors provide the triggers underlying the immunological events that shape the outcome of the diverse spectrum of autoimmune-based ocular surface disorders.

Advancements in anti-inflammatory therapy for dry eye syndrome

PURPOSE

The goal of this literature review is to discuss recent discoveries in the pathophysiology of dry eye and the subsequent evolution of diagnostic and management techniques. The mechanisms of various anti-inflammatory treatments are reviewed, and the efficacy of common pharmacologic agents is assessed. Anti-inflammatory therapy is evaluated in terms of its primary indications, target population, and utility within a clinical setting.

METHODS

The Medline PubMed database and the World Wide Web were searched for current information regarding dry eye prevalence, pathogenesis, diagnosis, and management. After an analysis of the literature, major concepts were integrated to generate an updated portrayal of the status of dry eye syndrome.

RESULTS

Inflammation appears to play a key role in perpetuating and sustaining dry eye. Discoveries of inflammatory markers found within the corneal and conjunctival epithelium of dry eye patients have triggered recent advancements in therapy. Pharmacologic anti-inflammatory therapy for dry eye includes 2 major categories: corticosteroids and immunomodulatory agents. Fatty acid and androgen supplementation and oral antibiotics have also shown promise in dry eye therapy because of their anti-inflammatory effects.

CONCLUSIONS

Anti-inflammatory pharmacologic agents have shown great success in patients with moderate to severe dry eye when compared with alternative treatment modalities. A deeper understanding of the link between inflammation and dry eye validates the utilization of anti-inflammatory therapy in everyday optometric practice.