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

Dysfunctional neural regulation of lacrimal gland secretion and its role in the pathogenesis of dry eye syndromes

Tears are a complex fluid consisting of three layers, each of which is secreted by a different set of tissues or glands. The aqueous portion of the tear film is produced predominantly by the lacrimal gland. Dry eye syndromes are diseases in which the amount and composition of tears are altered, which can lead to ocular surface damage. There are many causes for dry eye syndromes. One such cause is the alteration in the functions of nerves innervating the lacrimal gland and the ocular surface. The autoimmune disease Sjogren syndrome can deleteriously affect the innervation of the lacrimal gland. Damage to the sensory nerves in the ocular surface, specifically the cornea, as a result of refractive surgery and normal aging, prevents the normal reflex arc to the lacrimal gland. Both defects can result in decreased tear secretion and dry eye syndromes. This review will discuss the current information regarding neurally-stimulated protein, water, and electrolyte secretion from the lacrimal gland and delineate how nerve dysfunction resulting from a variety of causes decreases secretion from this gland.

Inflammation in dry eye

Dry eye is a condition of altered tear composition that results from a diseased or dysfunctional lacrimal functional unit. Evidence suggests that inflammation causes structural alterations and/or functional paralysis of the tear-secreting glands. Changes in tear composition resulting from lacrimal dysfunction, increased evaporation and/or poor clearance have pro-inflammatory effects on the ocular surface. This inflammation is responsible in part for the irritation symptoms, ocular surface epithelial disease, and altered corneal epithelial barrier function in dry eye. Anti-inflammatory therapies for dry eye target one or more of the inflammatory mediators/pathways that have been identified in dry eye.

Anti-inflammatory therapy of dry eye

As tear secretion and tear clearance decrease in the dry eye, an inflammatory response is initiated on the ocular surface that appears to involve both soluble and cellular mediators. Although the traditional approach to treating dry eye is to hydrate and lubricate the ocular surface with artificial tears, symptoms and/or sight-threatening corneal disease may persist in some patients on such aqueous enhancement therapies. In these patients, treatment with anti-inflammatory agents, such as cyclosporin A, corticosteroids, tetracyclines, or autologous serum, may be considered. Results of studies investigating the use of these agents are discussed. During treatment, patients should be conscientiously monitored for adverse effects.

Drainage of tears: impact on the ocular surface and lacrimal system

The human efferent tear ducts are part of the lacrimal system. Because little knowledge exists concerning the physiology of the nasolacrimal system, and hence its patho- physiology, the nasolacrimal system has received almost no consideration as a possible factor in dry eye. The human nasolacrimal ducts consist of the upper and the lower lacrimal canaliculus, the lacrimal sac, and the nasolacrimal duct. As a draining and secretory system, the efferent tear ducts play a role in tear transport and nonspecific immune defense. Moreover, components of tear fluid are absorbed in the nasolacrimal passage and are transported into a surrounding vascular system. This system is similar to a cavernous body that is subject to autonomic control and regulates tear outflow. Tear duct-associated lymphoid tissue (TALT) is present in the efferent tear ducts, displaying the cytomorphological and immunophenotypic features of mucosa-associated lymphoid tissue (MALT). Under normal conditions, tear fluid components are constantly absorbed into the blood vessels of the surrounding cavernous body. These vessels are connected to the blood vessels of the outer eye and could act as a feedback signal for tear fluid production, which ceases if these tear components are not absorbed. In this way, dry eye could be initiated. Defective stimulation of TALT could result in abnormal immune deviation at the ocular surface, leading to an autoimmunological response that causes dry eye pathology.

Evaluation of ocular surface inflammation in the presence of dry eye and allergic conjunctival disease

The ocular inflammatory diseases dry eye and allergic conjunctivitis are mediated by CD4+ T cells. Th1 cells secrete interferon (IFN)-gamma and are implicated in mediating the disease process in dry eye. Allergic conjunctivitis has been classically defined as a Th2 disease because of the predominance of Th2 cytokines interleukin (IL)-4 and IL-13. A multi-hit antigen challenge mouse model of allergic conjunctivitis provides evidence that IFN-gamma, a Th1 cytokine, acts as an endothelium gatekeeper by regulating endothelial expression of vascular adhesion molecule-1 required for inflammatory conjunctival cell infiltration. Current research encourages an in-depth evaluation of the exact role Th1 and Th2 cells play in ocular inflammation.

Variation in the expression of inflammatory markers and neuroreceptors in human conjunctival epithelial cells

The purpose of this research was to investigate the role of neurogenic involvement in the etiopatho-genesis of ocular surface inflammation, with the final goal of identifying new potential anti-inflammatory agents. We describe the presence of two "classic" markers of inflammation (HLA-DR and ICAM-1) and some neuroreceptors in cultured human conjunctival epithelial cells under basal and pro-inflammatory conditions. Two markers of inflammation (HLA-DR, ICAM-1) and several neuroreceptor subtypes (M1-, M2-, and M3-muscarinic; alpha1A-, alpha1B-, alpha1D-, alpha2A-, alpha2B-, alpha2C-, beta1-, beta2-, and beta3-adrenergic) were analyzed in a normal human conjunctival epithelial cell line (IOBA-NHC). These markers were studied in basal conditions and under the influence of two pro-inflammatory cytokines: tumor necrosis factor alpha (TNF-alpha) and/or interferon gamma (IFN-gamma). Immunofluorescence (confocal microscopy), western blotting, or flow cytometry techniques were used. In basal conditions, epithelial cells expressed all inflammatory markers except HLA-DR. The addition of IFN-gamma enhanced expression of HLA-DR, ICAM-1, and M2-muscarinic receptor. TNF-alpha up-regulated the expression of ICAM-1. When epithelial cells were incubated in the presence of both cytokines together, the cell surface expression of HLA-DR, ICAM-1, alpha1B-, and alpha2B-adrenergic receptors was increased. Cultured human conjunctival epithelial cells have been shown to be susceptible to up-regulation of the expression of inflammatory markers and cell membrane expression of some neuroreceptors under pro-inflammatory conditions. Consequently, pharmacologic neuro-modulation could have a role in the comprehensive management of ocular surface inflammation.

Sjogrens syndrome as failed local immunohomeostasis: prospects for cell-based therapy

Sjogrens syndrome has been estimated to affect between 0.2% and 2% or more of the population. It is an autoimmune disease with the hallmark histopathology of focal, periductal, and perivascular CD4(+) cell infiltration of the lacrimal and salivary glands. The immunohistopathology is typically associated with severe lacrimal and salivary dysfunctions, which contribute to debilitating ocular surface and oral symptoms. The quality of life of patients with Sjogrens syndrome often is degraded further by serious, multisystemic manifestations, and they are subject to a forty-fold increased risk of developing B cell lymphomas. In normal lacrimal glands, secretory epithelial cells, autoimmune effector lymphocytes, and regulatory lymphocytes can be seen as collaborating to maintain a local immunohomeostasis. The epithelium contributes by secreting immunomodulatory paracrine factors and also by continuously exposing autoantigens, which thereby become available for uptake by professional antigen presenting cells (APCs). Local or systemic perturbations may initiate autoimmune pathophysiology by impairing the replacement of normally-turning-over regulatory cells, by altering epithelial production of immunomodulatory paracrine factors, by inducing intact epithelial cells to begin secreting previously cryptic epitopes (epitopes that previously were not available to bind to major histocompatibility complex (MHC) molecules and so could not be recognized by T cell antigen receptors), and by inducing epithelial cells to begin expressing MHC Class II molecules and presenting formerly cryptic epitopes directly to CD4(+) cells. This process has been modeled ex vivo with mixed cell reactions comprised of isolated epithelial cells and autologous lymphocytes. This development has occurred as studies of anterior chamber-associated immune deviation (ACAID) and other immunoregulatory phenomena have elucidated the origins and functions of several different kinds of regulatory lymphocytes and shown that regulatory lymphocytes can be generated ex vivo. It now is possible to envision strategies for exploiting each possible mode of epithelial autoantigen exposure to produce therapeutic regulatory cells that might be capable of re-establishing normal immunohomeostasis. Consideration of the hypothetical therapies identifies a number of basic questions that warrant investigation.

Effect of hinge position on corneal sensation and dry eye after laser in situ keratomileusis using a femtosecond laser

PURPOSE

To determine whether hinge position has an effect on corneal sensation and dry-eye symptoms after myopic laser in situ keratomileusis (LASIK) performed with the IntraLase femtosecond laser (IntraLase Corp.).

SETTING

University-based academic practice, Ann Arbor, Michigan, USA.

METHODS

Sixty-six consecutive eyes of 33 patients were prospectively evaluated in a randomized contralateral-eye study to compare the difference between superior-hinge and temporal-hinge locations after bilateral myopic LASIK with the IntraLase femtosecond laser. Central Cochet-Bonnet esthesiometry, the Ocular Surface Disease Index (OSDI) questionnaire, Schirmer test with anesthesia, tear breakup time (TBUT), corneal fluorescein, and conjunctival lissamine green staining were evaluated preoperatively as well as 1 week and 1, 3, 6, and 12 months after surgery.

RESULTS

Corneal sensation was reduced with both superior-hinged and temporal-hinged LASIK flaps 1 week and 1, 3, 6, and 12 months after surgery (P<.0001). There was no difference in corneal sensation between superior-hinged and temporal-hinged flaps at any time point. The OSDI score was increased in 22.6% of patients at 1 week and 21.9% at 1 month (P<.00001), and corneal fluorescein staining was increased in 18% at 1 week. There were no differences in the OSDI, Schirmer with anesthesia, TBUT, corneal fluorescein, or conjunctival lissamine green staining when preoperative values and hinge location were compared.

CONCLUSIONS

Mild dry-eye disease was present early after myopic LASIK with the IntraLase laser. Hinge position had no effect on central corneal sensation or dry-eye disease.

Eye Dryness Sensations After Refractive Surgery: Impaired Tear Secretion or "Phantom" Cornea?

The cornea is richly innervated by various functional types of sensory nerve fibers. When stimulated, these fibers evoke conscious sensations of different quality including ocular dryness, discomfort, and pain. Refractive surgery involves a variable degree of damage to corneal nerves. This leads to an altered expression of membrane ion channels at the injured and regenerating nerve fibers, giving rise to aberrant spontaneous and stimulus-evoked nerve impulse firing. It is speculated that these abnormal sensory discharges are read by the brain as ocular surface dryness. This would explain the high incidence of eye dryness sensations after photorefractive surgery, which are experienced by a large number of patients despite the often modest disturbance of tear secretion. Therefore, drugs that reduce abnormal activity in injured nerves may represent a therapeutic alternative for eye dryness sensations after refractive surgery.

Impression cytology of the conjunctival epithelial cells in patients with cystic fibrosis

PURPOSE

Cystic fibrosis (CF) is the most frequent lethal autosomal recessive hereditary disorder. The disease affects all secretory epithelia, including the eye, and belongs to the group of ocular surface epithelial diseases, termed keratoconjunctivitis sicca or dry eye syndrome. The aim of this study was to evaluate goblet cell population and conjunctival epithelial morphology in patients with CF.

METHODS

A total of 20 CF patients and 20 controls underwent conjunctival impression cytology.

RESULTS

Impression cytology showed conjunctival squamous metaplasia and goblet cell loss in patients with CF.

CONCLUSION

Reduced goblet cell numbers and squamous metaplasia may be indicative of a higher degree of epithelial damage of conjunctival epithelial cells in CF patients, and the presence of neutrophils is a strong sign for an inflammatory background of this disease.In view of the simple, noninvasive nature of impression cytology, this technique may prove to be an important tool for the diagnosis and monitoring of dry eye changes in CF patients.

Nitric oxide synthase induction and cytotoxic nitrogen-related oxidant formation in conjunctival epithelium of dry eye (Sjögren's syndrome)

Until now, the expression and possible role of nitric oxide and nitrogen related oxidants in the human dry eye have not been investigated. Therefore, we examined immunohistochemically nitric oxide synthase isomers (NOS), enzymes generated nitric oxide, nitrotyrosine, a cytotoxic byproduct of nitric oxide and malondialdehyde, a byproduct of lipid peroxidation, in conjunctival epithelium of patients with dry eye, Sjögren's syndrome (SS). Moreover, in conjunctival epithelium of patients with dry eye (SS) the immunohistochemical staining of some pro-inflammatory cytokines was demonstrated: mature interleukin-1 beta (IL-1beta), interleukin 6 (IL-6), interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha). Conjunctival epithelial cells were obtained by the method of impression cytology. Normal eyes served as controls. In contrast to the normal eyes where endothelial nitric oxide synthase (NOS3) as well as inducible nitric oxide synthase (NOS2) were only slightly expressed in conjunctival epithelium, in dry eye both NOS (mainly NOS2) were gradually expressed along the severity of dry eye symptoms which was in accord with pro-inflammatory cytokine immunodetection (IL-1beta, IL-6, IL-8, TNF-alpha) in dry eye conjunctival cytology samples. This was in contrast to normal eyes where the staining of pro-inflammatory cytokines was weak or completely absent. Peroxynitrite formation (demonstrated by nitrotyrosine residues) and lipid peroxidation (evaluated by increased malondialdehyde staining) were also found in conjunctival epithelium of dry eye with highly pronounced symptoms of dryness. In conclusion, results point to the suggestion that reactive nitrogen species are involved in the pathogenesis or self-propagation of autoimmune dry eye (SS).

Functional Foxp3+ CD4+ CD25(Bright+) "natural" regulatory T cells are abundant in rabbit conjunctiva and suppress virus-specific CD4+ and CD8+ effector T cells during ocular herpes infection

We studied the phenotype and distribution of "naturally" occurring CD4(+) CD25(+) T regulatory cells (CD4(+) CD25(+) nT(reg) cells) resident in rabbit conjunctiva, the main T-cell inductive site of the ocular mucosal immune system, and we investigated their suppressive capacities using herpes simplex virus type 1 (HSV-1)-specific effector T (T(eff)) cells induced during ocular infection. The expression of CD4, CD25, CTLA4, GITR, and Foxp3 was examined by reverse transcription-PCR, Western blotting, and fluorescence-activated cell sorter analysis in CD45(+) pan-leukocytes isolated from conjunctiva, spleen, and peripheral blood monocyte cells (PBMC) of HSV-1-infected and uninfected rabbits. Normal conjunctiva showed a higher frequency of CD4(+) CD25((Bright+)) T cells than did spleen and PBMC. These cells expressed high levels of Foxp3, GITR, and CTLA4 molecules. CD4(+) CD25((Bright+)) T cells were localized continuously along the upper and lower palpebral and bulbar conjunctiva, throughout the epithelium and substantia propria. Conjunctiva-derived CD4(+) CD25((Bright+)) T cells, but not CD4(+) CD25((low)) T cells, efficiently suppressed HSV-specific CD4(+) and CD8(+) T(eff) cells. The CD4(+) CD25((Bright+)) T-cell-mediated suppression was effective on both peripheral blood and conjunctiva infiltrating T(eff) cells and was cell-cell contact dependent but independent of interleukin-10 and transforming growth factor beta. Interestingly, during an ocular herpes infection, there was a selective increase in the frequency and suppressive capacity of Foxp3(+) CD4(+) CD25((Bright+)) T cells in conjunctiva but not in the spleen or in peripheral blood. Altogether, these results provide the first evidence that functional Foxp3(+) CD4(+) CD25((Bright+)) T(reg) cells accumulate in the conjunctiva. It remains to be determined whether conjunctiva CD4(+) CD25(+) nT(reg) cells affect the topical/mucosal delivery of subunit vaccines that stimulate the ocular mucosal immune system.

A single injection of interleukin-1 induces reversible aqueous-tear deficiency, lacrimal gland inflammation, and acinar and ductal cell proliferation

Emerging studies from our laboratory demonstrate that interleukin-1 (IL-1) family members play a major role in impairing lacrimal gland functions. Here we have extended our investigations to observe the effects of IL-1 on aqueous tear production, lacrimal gland secretion, lacrimal gland histology, and acinar and ductal cell proliferation. We demonstrate that a single injection of IL-1 into the lacrimal glands inhibited neurally- as well as agonist-induced protein secretion resulting in decreased tear output. Meanwhile, IL-1 injection induced a severe, but reversible (7-13 days), inflammatory response that led to destruction of lacrimal gland acinar epithelial cells. Finally, we demonstrate that as the inflammatory response subsided and lacrimal gland secretion and tear production returned to normal levels, there was increased proliferation of acinar and ductal epithelial cells. Our work uncovers novel effects of IL-1 on lacrimal gland functions and the potential regenerative capacity of the mouse lacrimal gland.

The use of impression cytology in the follow-up of severe ocular burns

AIMS

To evaluate by impression cytology (IC) the expression of the MHC class II inflammatory marker HLA-DR by the conjunctival epithelium, the cytological modifications of the conjunctival surface according to the Nelson's classification, and the eventual correlation between the two after severe ocular burns.

METHODS

A total of 24 patients (24 eyes) who presented with severe ocular burns underwent IC. We compared them with 18 healthy eyes. HLA-DR expression was studied by flow cytometry as well as the conjunctival histology evaluated with the Nelson's classification from 2-24 months after the onset of burns.

RESULTS

There was a significant upregulation of the expression of HLA-DR in eyes with burns compared to the healthy population at 2 months (p<0.001), 6 months (p<0.001), 12 months (p = 0.019), 18 months (p = 0.0171) and 24 months (p = 0.01766). A significant difference was found between the Nelson grade in the pathological population and those of the healthy population at 2 months (p = 0.0157). HLA-DR upregulation was significantly correlated with the Nelson's grades between 2 months (r = 0.69, p<0.0001) and 6 months (r = 0.61, p = 0.0001).

CONCLUSION

The IC technique can act as a useful tool for following-up ocular surface inflammation after severe ocular burns.

Targeting Contact Lens Induced Dryness and Discomfort: What Properties Will Make Lenses More Comfortable

There are about 35 million contact lens wearers in North America, and about half of them are symptomatic of dryness and discomfort, more commonly experienced at the end of the lens wearing day. Most of these contact lens wearers do not suffer from true dry eye, which is a pervasive and ubiquitous disease or condition that affects many millions of people in North America. It seems fairly clear that the lens causes the eye to become uncomfortable or "dry," and unless it is effectively remedied, the patient will most likely discontinue lens wear. This review describes the dryness and discomfort effects of contact lenses and how contact lens properties with novel solutions have the potential for eliminating or alleviating these symptoms.

The Definition and Classification of Dry Eye Disease: Report of the Definition and Classification Subcommittee of the International Dry Eye Workshop (2007)

The aim of the DEWS Definition and Classification Subcommittee was to provide a contemporary definition of dry eye disease, supported within a comprehensive classification framework. A new definition of dry eye was developed to reflect current understanding of the disease, and the committee recommended a three-part classification system. The first part is etiopathogenic and illustrates the multiple causes of dry eye. The second is mechanistic and shows how each cause of dry eye may act through a common pathway. It is stressed that any form of dry eye can interact with and exacerbate other forms of dry eye, as part of a vicious circle. Finally, a scheme is presented, based on the severity of the dry eye disease, which is expected to provide a rational basis for therapy. These guidelines are not intended to override the clinical assessment and judgment of an expert clinician in individual cases, but they should prove helpful in the conduct of clinical practice and research.

Research in Dry Eye: Report of the Research Subcommittee of the International Dry Eye WorkShop (2007)

Members of the DEWS Research Subcommittee reviewed research into the basic mechanisms underlying dry eye disease. Evidence was evaluated concerning the tear film, lacrimal gland and accessory lacrimal glands, ocular surface epithelia (including cornea and conjunctiva), meibomian glands, lacrimal duct system and the immune system. Consideration was given to both animal and human research data. Results are presented as a series of information matrices, identifying what is known and providing supporting references. An attempt is made to identify areas for further investigation.

Symptomatic dry eye treatment with autologous platelet-rich plasma

BACKGROUND

Autologous platelet-rich plasma (PRP) has been proven to be very effective on tissue regeneration and wound healing. Here we investigate the potential use of PRP in the treatment of symptomatic dry eye.

METHODS

Eighteen consecutive patients with symptomatic dry eye were treated with topical PRP and followed up for 1 month. Disappearance of subjective symptoms, increase in best corrected visual acuity, tear meniscus, tear breakup time, decrease in inflammation, fluorescein staining and improvement in impression cytology were measured.

RESULTS

Symptoms improved significantly in 89% of the patients, 28% improved at least 1 line of best corrected visual acuity. A significant improvement on lachrymal meniscus and conjunctival hyperemia and a decrease or disappearance of corneal fluorescein staining were observed. Impression cytology revealed a significant increase in conjunctival goblet cells.

CONCLUSION

Treatment of patients suffering from significant dry eye symptoms with autologous RPR proved to be very effective, improving both patient symptoms and major clinical signs.

[Ocular surface investigations in dry eye]

Dry eye is a complex clinicopathological entity involving tear film, lacrimal glands, eyelids, and a wide spectrum of ocular surface cells, including epithelial, inflammatory, immune, and goblet cells. From the tightly regulated lacrimal film functions and structure, a large variety of investigations have been developed, including tear meniscus measurements, fluorophotometry, meibometry, interference pattern analysis, evaporation rate, tear osmolarity, and thermography. Dry eye conditions also interfere with the ocular surface, causing corneal irregularities that may be explored using the techniques of videokeratography and in vivo confocal microscopy, or optical impairment, as confirmed by aberrometry. At the level of ocular surface cells, impression cytology remains a standard for assessing cell alterations. It has greatly benefited from new confocal microscopy, molecular biology, and flow cytometry techniques. Biological assessment of tear proteins or other mediators is also useful. Major limits should be acknowledged, however, such as technical issues in tear film collection, especially in dry eyes, and the lack of standardization of most measurements. Tear osmolarity, electrophoresis, and dosage of normal tear proteins, such as lysozyme or lactoferrin, remain the most useful tests. Finally, some extraocular explorations such as accessory gland biopsy or serum antinuclear antibody dosage may be useful for assessing the diagnosis of Sjögren's syndrome.

Effect of an oil-in-water emulsion on the tear physiology of patients with mild to moderate dry eye

PURPOSE

To determine the effect of an oil-in-water emulsion eye drop compared with a conventional dry eye supplement (hypromellose) on tear physiology in dry eye.

METHODS

A randomized parallel, longitudinal, and investigator-masked study of the efficacy of 1.25% castor oil emulsion and 0.32% hypromellose solution was carried out. A total of 53 patients with mild to moderate dry eye (27 in emulsion group and 26 in hypromellose group) were recruited for the study. Patients were enrolled if they reported at least 2 symptoms on a McMonnies Dry Eye Questionnaire together with 1 of the following screening tests: noninvasive tear breakup time (5-10 seconds) and Schirmer test without anesthesia (2-5 mm in 5 minutes). Patients were instructed to use the test solutions 3 times a day for 30 days. Tear production, evaporation, lipid layer structure, and osmolality were measured before and 30 days after use of the drops.

RESULTS

A statistically significant decrease was seen after 1 month in tear evaporation rates with both emulsion (7.25 +/- 5.43 g/m2/h) and hypromellose (2.02 +/- 4.75 g/m2/h). However, the decrease with emulsion was significantly greater than with hypromellose (P < 0.001). Lipid layer structure improved from day 1 to day 30 of the study with the emulsion but not with the hypermellose. No significant changes were seen in tear production and osmolality with either of the drops.

CONCLUSIONS

The oil-water emulsion was more effective in reducing tear evaporation than hypromellose after repeated application over a 1-month period. This finding signifies the potential of the emulsion in the management of evaporative dry eye.

Effect of topical cyclosporine on tear functions in tear-deficient dry eyes

We evaluated the efficacy of topical 2% cyclosporine drops in the treatment of tear-deficient dry eye because of acquired primary lachrymal disease (APLD; 15 patients) and Sjögren syndrome (SS; 15 patients). Symptoms of dryness tended to improve in patients with SS. Schirmer score improved in patients with APLD. Topical CsA 2% drops appears to be safe and effective in the treatment of dry eye patients because in patients with APLD and SS, there is trend toward improvement.

Exposure to a dry environment induces strain-specific responses in mice

Most current animal models of dry eye have a single causative mechanism and do not take into consideration the influence of environmental conditions on tear secretion and associated ocular surface signs. Since immunity and inflammation have been implicated in dry eye pathogenesis, and different mouse strains are known to have differentially biased immune responses, we conducted the present study to test the hypothesis that strains with specifically polarized T cell responses (T helper-1 [Th1] vs. T helper-2 [Th2]) develop differential signs of dry eye when exposed to a controlled low humidity setting. Eight to 12-week-old BALB/c (Th2 biased) and C57BL/6 (Th1 biased) mice were placed in a controlled environment chamber (CEC) where relative humidity (RH), temperature (T), and air flow (AF) were continuously regulated and monitored. Mice were exposed to specific environmental controlled conditions (RH=15.5+/-3.8%, AF=15 l/min, T=21-23 degrees C) for 3 to 7 days. Aqueous tear production by means of the cotton thread test, corneal fluorescein staining (NEI grading scheme, score 0-15) and goblet cell density in the superior and inferior conjunctivae were measured by a masked observer. No statistically significant differences between the groups were found at baseline. Statistically significant decreases in tear secretion were seen after exposure to the CEC environment. Mean cotton thread wetting was 1.9+/-0.2 (baseline), 1.4+/-0.3 (day 3), and 0.9+/-0.2 mm (day 7) for BALB/c mice, and 1.7+/-0.3 (baseline), 0.9+/-0.3 (day 3), and 0.4+/-0.2 mm (day 7) for C57BL/6 mice. These mice showed reduced tear secretion as compared to BALB/C at each time point tested (P<.005, t-test). Both BALB/c and C57BL/6 mice showed a significant increase in corneal fluorescein staining at both day 3 and day 7 as compared to baseline. With exposure to the CEC goblet cell density significantly decreased in the superior and inferior conjunctivae in BALB/c mice, while it remained unchanged in C57BL/6 mice. This study indicates that exposure of non-pharmacologically modified mice to a low humidity environment in the CEC can lead to significant alterations in tear secretion, goblet cell density, and acquisition of dry eye-related ocular surface signs which are strain-specific.

PACAP induces neurite outgrowth in cultured trigeminal ganglion cells and recovery of corneal sensitivity after flap surgery in rabbits

PURPOSE

To evaluate the ability of pituitary adenylate cyclase-activating polypeptide (PACAP) to induce growth of neuronal processes in cultured trigeminal ganglion cells, and to accelerate neurite outgrowth and recovery of corneal sensitivity after creation of a corneal flap in a rabbit model of laser-assisted in situ keratomileusis (LASIK) surgery.

DESIGN

Animal study.

METHODS

The cDNA of rabbit PACAP was sequenced, and the expression of PACAP receptors in the trigeminal ganglia from rabbits was quantified by quantitative real-time polymerase chain reaction. Trigeminal ganglion cells were isolated from rabbits and cultured for 48 hours with or without PACAP27 (bioactive N-terminal peptide from PACAP). Cells were stained with antibody against neurofilaments, and neurite outgrowth was quantified by cell counting. In the rabbit LASIK model, a corneal flap with a planned thickness of 130 microm and 8.5 mm diameter was created with a microkeratome. The rabbits then received eyedrops containing PACAP27 four times a day for eight weeks, and corneal sensitivity was measured. Neurite outgrowth was assessed by staining histologic sections of the flap area for cholinesterase.

RESULTS

The deduced amino acid sequence of PACAP in rabbit was identical to that of human. PACAP receptor, PAC1, was highly expressed in trigeminal ganglia from newborn and adult rabbits. PACAP27 at 1 microM induced growth of neuronal processes in cultured primary trigeminal ganglion cells. In the LASIK model, extensions of neuronal processes from amputated nerve trunks in cornea were observed after administration of eyedrops containing 1 or 10 microM PACAP27. The 10 microM PACAP27 treatment also greatly accelerated recovery of corneal sensitivity.

CONCLUSIONS

PACAP may be a candidate drug for ameliorating dry eye after LASIK surgery.

Effect of antibacterial honey on the ocular flora in tear deficiency and meibomian gland disease

PURPOSE

To assess for differences in the ocular flora of patients with dry eye caused by tear deficiency and/or meibomian gland disease and to assess the effect of antibacterial honey on the ocular flora in these forms of dry eye.

METHODS

In this prospective, open-label pilot study, bacteria isolated from the eyelid margin and conjunctiva were identified and quantified before and at 1 and 3 months after initiation of treatment with topical application of antibacterial honey 3 times daily. Subjects had non-Sjogren tear deficiency (n = 20), Sjogren syndrome tear deficiency (n = 11), meibomian gland disease (n = 15), and non-Sjogren tear deficiency with meibomian gland disease (n = 20), and there were 18 non-dry eye subjects.

RESULTS

The total colony-forming units (CFUs) isolated from each of the dry eye subgroups before antibacterial honey use was significantly greater than the total CFU isolated from the non-dry eye group. Antibacterial honey use significantly reduced total CFUs for the eyelids and the conjunctiva of dry eye subjects from baseline at month 1 (eyelids: P = 0.0177, conjunctiva: P = 0.0022) and month 3 (eyelids: P < 0.0001, conjunctiva: P < 0.0001). At month 3, there were reductions in total CFUs for all dry eye subgroups such that the CFUs were not significantly different from those of the non-dry eye group.

CONCLUSION

From these results, there is sufficient preliminary data to warrant further study of the effects of antibacterial honey in chronic ocular surface diseases.

Lymphocytic infiltration and goblet cell marker alteration in the conjunctiva of the MRL/MpJ-Fas(lpr) mouse model of Sjögren's syndrome

Sjögren's syndrome is an autoimmune disorder characterized by a progressive, immune-mediated destruction of mucosal tissues such as the lacrimal and salivary glands, leading to ocular and oral dryness. The MRL/MpJ-Fas(lpr) mouse is one of the animal models used to study this disease. However, little is known about the potential alterations in the conjunctiva in this murine model. The purpose of this study was to determine: (1) whether the conjunctiva is infiltrated by T lymphocytes, (2) characterize the type, amount and temporal sequence of the inflammatory infiltrates, and (3) investigate whether the amount of conjunctival goblet cells is altered in this murine model of Sjögren's syndrome. Female 4-, 9-, 13-, 16-, and 18-/20-wk-old MRL/MpJ-Fas(lpr) (lpr, diseased) and congenic MRL/MpJ (+/+, control) mice were used. Right eyes were either fixed, frozen, cryosectioned, and studied by immunofluorescence microscopy or the conjunctiva was removed, homogenized and analyzed by electrophoresis and Western blot analysis. The following antibodies were used: anti-CD3 (specific T lymphocyte marker), anti-cytokeratin 7 (CK-7), anti-PKD (formerly known as PKCmu, both markers of goblet cell bodies), anti-PGP 9.5 (pan-neuronal marker), anti-VIP and TH (markers for parasympathetic and sympathetic nerves, respectively), anti-adrenergic (alpha(1) and beta(1-3)) and muscarinic (M(1)-M(3)) receptor subtypes (markers for neurotransmitter receptors of the sympathetic and parasympathetic pathways, respectively). Left eyes were fixed, embedded, sectioned, and stained. Hematoxylin/eosin, Giemsa, or alcian blue/periodic acid Schiff's reagent were used to study lymphocyte infiltration; to determine the presence of eosinophils, neutrophils, and mast cells; and to count the number of goblet cells, respectively. By immunofluorescence microscopy, lymphocytes were detected in the conjunctiva of 9-wk-old lpr, but not +/+, mice. The lymphocytic infiltration became more extensive as the animals aged, with 16- and 18-/20-wk lpr mice appearing to have a greater lymphocytic infiltration than +/+ mice at the same age. By Western blot analysis, the amount of CD3 was enhanced in lpr compared to +/+ mice by the 16th wk, but not by the 9th wk. No major differences in the presence of eosinophils, neutrophils and degranulated mast cells between lpr and +/+ mice were observed. By light microscopy, a significant increase in goblet cell number was found in lpr mice compared to +/+ mice at 16 wks on. By Western blotting, the amount of CK-7 was significantly increased at 9 wks on and the amount of PKD was significantly increased at 16 wks. By immunofluorescence microscopy, there were no major differences in distribution of sympathetic and parasympathetic nerves present in the lpr conjunctiva compared to that of +/+ mice at any ages, although slight differences were observed with increased age. Muscarinic receptor expression was decreased, as less M(3) receptor subtype-associated immunofluorescence was detected in older lpr mice compared to +/+ mice and confirmed by Western blot analysis. No differences in the localization or the amount of alpha(1)- or beta(1-3)-adrenergic receptor immunodetection were observed between lpr and +/+ mice. We conclude that the conjunctiva is a target tissue in Sjögren's syndrome-related inflammation in this murine model.

Pathophysiology of Sjögren's syndrome

The term Sjögren's syndrome refers to keratoconjunctivitis sicca and xerostomia due to lymphocytic infiltrates of lachrymal and salivary glands. The current used criteria for diagnosis of primary Sjögren's syndrome is the American-European consensus. Primary Sjögren's syndrome is an autoimmune disorder characterized by lymphocytic infiltrates and destruction of the salivary and lachrymal glands and systemic production of autoantibodies to the ribonucleoprotein particles SS-A/Ro and SS-B/La. The infiltrating cells (T- and B-cells, dendritic cells) interfere with glandular function at several points: destruction of glandular elements by cell-mediated mechanisms; secretion of cytokines that activate pathways bearing the signature of type 1 and 2 interferons; production of autoantibodies that interfere with muscarinic receptors; and secretion of metalloproteinases (MMPs) that interfere with the interaction of the glandular cell with its extracellular matrix, which is necessary for efficient glandular function. As the process progresses, the mucosal surfaces become sites of chronic inflammation and the start of a vicious circle. Despite extensive study of the underlying cause of Sjögren's syndrome, the pathogenesis remains obscure. In broad terms, pathogenesis is multifactorial; environmental factors are thought to trigger inflammation in individuals with a genetic predisposition to the disorder.

Long-term Resolution of Chronic Dry Eye Symptoms and Signs after Topical Cyclosporine Treatment

PURPOSE

To report the resolution of symptoms and signs of chronic dry eye for at least 1 year after completion of a minimum 6-month course of topical 0.05% cyclosporine in a subgroup of patients from 2 practices.

DESIGN

Retrospective case series.

PARTICIPANTS

Eight patients who had had chronic dry eye disease for 3 to 20 years were treated with topical cyclosporine for 6 to 72 months, and then remained free of symptoms or signs of disease for at least 1 year (range, 16-29 months; mean, 21 months) after stopping treatment.

INTERVENTION

Treatment with topical 0.05% cyclosporine with or without topical corticosteroids twice a day along with nonpreserved artificial tears. Tests performed were patient history, slit-lamp examination, rose bengal and fluorescein staining of the ocular surface, tear breakup time, and Schirmer's test with anesthesia.

MAIN OUTCOME MEASURES

Resolution of all symptoms and signs of dry eye disease after a minimum 6-month course of topical 0.05% cyclosporine.

RESULTS

Eight patients, including approximately 4% of the total patients with chronic dry eye treated with 0.05% cyclosporine in one author's practice, were free of signs or symptoms of dry eye disease a minimum of 1 year after completing a 6- to 72-month course of therapy. There were no parameters noted that distinguished these patients from others who required maintenance topical cyclosporine or who did not appear to respond to topical cyclosporine.

CONCLUSIONS

Topical cyclosporine treatment appears to be associated with a cure of symptoms and signs in a subgroup of chronic dry eye patients. In such patients, presumably there is effective elimination of inflammatory processes underlying chronic dry eye disease. Such patients should be monitored long term because a return of disease may be noted. These results suggest that topical cyclosporine treatment halts progression of chronic dry eye in some patients.

Is it safe to use topical NSAIDs for corneal sensitivity in Sjögren’s syndrome patients?

Sjögren's syndrome dry eye is an inflammatory disease accompanied by an impairment of the autonomous nervous system of the ocular surface. The therapy for this condition is shifting from the mere tear replacement to a more complex approach including an anti-inflammatory treatment. Clinical trials have evidenced that the use of NSAIDs is followed by a reduction of the ocular discomfort symptoms in dry-eye patients. However, sporadic case reports of corneal melting in dry-eye subjects who underwent surgical procedures has brought attention to the possible effect that NSAIDs may have on corneal sensitivity. Therefore, the effect of NSAID treatment on corneal sensitivity in normal subjects and in patients with dry eye was studied. The results of these trials seem to demonstrate that some NSAIDs, diclofenac in particular, have the effect of reducing corneal sensitivity both in normal subjects and in patients with dry eye. Therefore, NSAIDs should be used with caution in Sjögren's syndrome patients.

Prevalence of Dry Eye in Bangkok, Thailand

PURPOSE

To estimate the prevalence of dry eye in the adult population of Bangkok, Thailand.

METHODS

Five hundred fifty volunteers 40 years of age or more who presented to the Ramathibodi Hospital for annual eye examinations were enrolled. Interviewers administered a dry eye symptoms questionnaire. Slit-lamp examination and objective dry eye assessment consisting of tear film breakup time (TBUT), fluorescein corneal staining, Schirmer tests, and meibomian gland evaluation were performed. Outcome measures included frequency of symptoms and positive dry eye tests.

RESULTS

Thirty-four percent reported significant symptoms, which were defined as having one or more symptoms often or all of the time (95% confidence interval, 28.1-40.6). Approximately one half had meibomian gland disease (MGD) or pingueculum/pterygium (46.2 and 53.8%, respectively). Individuals with significant symptoms tended to be women (83.4%, P = 0.024), had MGD (63.6%, P = 0.006), had current artificial tear use (33.2%, P = 0.024), and had positive TBUT (80.7%, P = 0.000) and fluorescein staining (16.6%, P = 0.013.) The presence of pingueculum/pterygium and MGD were significantly associated with positive dry eye tests.

CONCLUSION

This is the first report of prevalence of dry eye inclusive of signs and symptoms in an elderly Thai population. The prevalence of disease diagnosed on the basis of symptoms and dry eye tests was approximately 2 to 3 times higher than reported in whites. Women were more likely to report symptoms. Positive associations with dry eye tests were found in subjects with pingueculum/pterygium and MGD.

Effect of Topical Ophthalmic Epinastine and Olopatadine on Tear Volume in Mice

PURPOSE

To investigate the effects of topical epinastine and olopatadine on tear volume by using a mouse model.

METHODS

Eighty-five C57BL6 mice (170 eyes) were treated twice daily with topical ophthalmic epinastine 0.05%, olopatadine 0.1%, or atropine 1% or served as untreated controls. A thread-wetting assay was used to measure tear volume at baseline and 15, 45, 90, 120, and 240 minutes after the last instillation of the drug on days 2 and 4 of treatment.

RESULTS

After 2 days of treatment, epinastine-treated mice showed greater mean tear volumes than olopatadine-treated mice did at 15, 45, 90, and 240 minutes, with statistical significance at 15 and 45 minutes (P<0.001). Olopatadine significantly reduced tear volume versus untreated controls at 15 and 45 minutes (P<0.001). After 4 days, tear volumes with epinastine treatment exceeded those with olopatadine treatment at all time points, with statistical significance at 45 minutes (P<0.05). Atropine rendered tears undetectable at 15, 45, and 90 minutes; tear volume returned to baseline levels at 240 minutes.

CONCLUSIONS

Topical epinastine did not inhibit tear secretion, whereas olopatadine caused a significant decrease in tear volume. Because of its neutral impact on the lacrimal functional unit, epinastine may be an especially good choice for the treatment of allergic conjunctivitis in patients with dry eye disease or in those who are at risk for developing dry eye.

Development of immortalized rat conjunctival epithelial cell lines: an in vitro model to examine transepithelial antigen delivery

The objective of these studies was to develop conjunctival epithelial cell lines for investigation of antigen translocation across a mucosal barrier. Conjunctival epithelial cells from Fischer 344 rats were immortalized with pSV3(neo) resulting in two cell lines--CJ4.1A and CJ4.3C. Each formed confluent cell layers with epithelial morphology when grown on permeable membrane filters. They expressed the SV40 T antigen, the conjunctiva-specific cytokeratin 4, the goblet cell-specific cytokeratin 7 and were negative for the corneal epithelial cell-specific cytokeratin 12. The cell lines have been in culture for over 60 passages, and the population doubling times were 22+/-7h for CJ4.1A and 23+/-9h for CJ4.3C. When grown on Transwell membranes, each cell line achieved a transepithelial electrical resistance of 600-800 Omega cm2 by 3-4 days and maintained a high resistance for several days. Both cell lines expressed zona occludens-1 at confluence. At 24h following addition of 250 microg of FITC-labeled ovalbumin to the apical chambers, 15+/-6 microg could be detected in the basal chamber of CJ4.1A and 6+/-1 microg in the basal medium of CJ4.3C. In contrast, 82+/-6 microg was detected in the lower chambers of cell-free Transwells. Similarly, Transwells containing confluent CJ4.1A or CJ4.3C cells impeded passage of 0.1 microm diameter polystyrene microspheres (5+/-1% and 4+/-1%, respectively, of the apical input), compared to 26+/-6% of the input microspheres recovered from the basal chambers of cell-free Transwells. Pretreatment with 4mM EGTA for 10 min caused an increase in OVA-FITC translocation across CJ4.3C cells. Incubation in the presence of 4mM EGTA significantly increased OVA-FITC translocation across both cell lines, relative to untreated cell layers. Morphological and functional characterization indicates that these cells provide a useful experimental tool to assess strategies for enhancing transepithelial antigen uptake.

Increasing importance of dry eye syndrome and the ideal artificial tear: consensus views from a roundtable discussion

BACKGROUND

Dry eye syndrome is a highly prevalent, yet largely under diagnosed, condition that can substantially affect quality of life. Left untreated, dry eye is associated with chronic eye pain and increased risk of ocular surface disease. Current demographic changes and lifestyle factors indicate that the dry eye syndrome patient population will increase significantly, ensuring that general practitioners and ophthalmic clinicians alike will experience more patients presenting with dry eye symptoms. Greater public and practitioner awareness of emerging research, technologies, and therapies is crucial to ensuring appropriate interventions to meet specific patient needs and result in clinically favorable outcomes.

ROUNDTABLE ASSEMBLY

In August 2005, a team of ocular surface experts convened for a 1-day roundtable session to discuss the latest information on diagnosing and treating dry eye syndrome and real-world issues in artificial tear therapy, including preservative use.

ROUNDTABLE DISCUSSION

The discussion centered on the mild to moderate dry eye patient and critical features of the ideal artificial tear, which are preservative-free formulation, protection from microbial contamination, cost-effective, non-blurring, and easy to use. Products that match this profile have the advantage of being able to benefit the myriad of patients who comprise the dry eye syndrome population. Ocular surface health should always remain a top priority. Preferred Practice Pattern Dry Eye Syndrome Medical Treatment guidelines should be modified to recommend the use of preservative-free formula artificial tear products for all levels of dry eye conditions in consideration of the medical benefit they offer to dry eye syndrome sufferers.

CONCLUSION

The growing prevalence of dry eye syndrome demands increased attention. Further research, enhanced diagnostic tests, increased use of preservative-free artificial tear formulations as first-line therapy, greater patient-practitioner interaction, and patient education are warranted.

Conjunctival changes induced by LASIK suction ring in a rabbit model

PURPOSE

To study histopathological changes in rabbit conjunctiva after suction ring application.

METHODS

A suction ring was applied to adult albino rabbit eyes (n = 30) with a vacuum pressure of 508 mm Hg for 40 s. Three rabbits were sacrificed at 3 h (3-hour group), 6 h (6-hour group), 1 day (1-day group), 3 days (3-day group), and 7 days (7-day group) after the suction ring application. Histopathological examinations included hematoxylin and eosin, Alcian blue pH 2.5-periodic acid-Schiff (AB2.5-PAS), and Alcian blue pH 1.0-periodic acid-Schiff (AB1.0-PAS) staining. TdT-dUTP-terminal nick-end labeling (TUNEL) assay and immunohistochemical staining for p65 were also performed.

RESULTS

The site of suction ring application and adjacent areas did not show transient inflammation. AB2.5-PAS staining revealed that the percentage of neutral mucin was significantly different between 54.5 +/- 1.6% in the control group and 22.3 +/- 1.3% in the 7-day group (p = 0.04). Apoptosis occurred not only at the site of suction ring application, but also in adjacent regions. At all time points, conjunctival epithelium showed no positive staining for p65.

CONCLUSION

The transient elevation of pressure induced by a suction ring is sufficient to cause conjunctival damage. These histological results support the finding that conjunctival damage caused by suction ring application is one of many etiologies of dry eye syndrome following laser in situ keratomileusis.

[Sjögren's syndrome. Current aspects from a rheumatological point of view]

Sjögren's syndrome is an autoimmune disease of the exocrine glands characterized by the leading symptoms of keratoconjunctivitis and stomatitis sicca based on a complex pathogenesis. The prevalence is about 0.5-1%; primary Sjögren's syndrome is differentiated from secondary Sjögren's syndrome associated with other autoimmune disorders. The diagnosis is established by the presence of subjective complaints and objective evidence of sicca symptoms, anti-Ro(SSA)/La(SSB) antibodies, and/or focal lymphocytic infiltration of the glandular tissue. In addition to the typical sicca symptomatology, which is managed symptomatically by substitution and stimulation therapy, some patients exhibit extraglandular manifestations. Complaints involving the musculoskeletal system and inner ear dominate and are treated by the rheumatologist. The indication for base therapy is tailored to individual needs, but the efficacy of this approach has not been established in studies. About 5-10% of the patients with primary Sjögren's syndrome develop a B-cell non-Hodgkin's lymphoma. The disease requires interdisciplinary management including, among others, ophthalmologists, dentists, and otorhinolaryngologists, depending on the clinical picture.

Muscarinic receptors in the ocular surface

PURPOSE OF REVIEW

A wide distribution of the eye's muscarinic receptor system has been found and several roles for the muscarinic system in the eye proposed, although functional consequences of muscarinic receptor activation are not always fully characterized. The present paper reviews current knowledge about the presence of muscarinic receptors in the ocular surface and the implication of alterations on their expression and/or functioning in eye diseases.

RECENT FINDINGS

Several authors have described alterations in muscarinic receptor subtype expression in the eye under pathological conditions. In conjunctiva of vernal keratoconjunctivitis patients, the expression of muscarinic receptor subtypes is altered in both the epithelium and stroma. Under proinflammatory conditions, M2-muscarinic receptor expression is upregulated in conjunctival epithelial cells in vitro. M3-muscarinic receptor altered distribution has been found in the lacrimal gland of NOD mice.

SUMMARY

The cholinergic muscarinic system plays diverse roles. Alteration in the expression and/or functioning of muscarinic receptors may be implicated in the etiopathogenesis of some ocular diseases. Their pharmacological regulation may therefore have therapeutic value. Knowledge of the specific receptor subtypes expressed in each tissue may help to avoid some undesired secondary side effects in some cases when muscarinic agonists or antagonists are used.

A clinical study of the efficacy of topical corticosteroids on dry eye

OBJECTIVE

To evaluate the effect of topical corticosteroid for treatment of moderate or severe dry eye.

METHODS

Sixty eyes of 30 patients with moderate or severe dry eye, who were not sensitive to artificial tears, were treated with 0.1% fluorometholone eye drops. Subjective symptom and objective tests were used to evaluate the efficacy of treatment before and after application of 0.1% fluorometholone eye drops for 1 week and 1 month. Side effects were also evaluated.

RESULTS

After 1 week of treatment, subjective symptoms were improved in all dry eye patients; objective tests were improved in all dry eye patients 1 month after treatment, and the difference was significant.

CONCLUSION

Topical corticosteroid drops can rapidly and effectively relieve the symptoms and signs of moderate or severe dry eye.

Efficacy of topical cyclosporine 0.05% for prevention of cornea transplant rejection episodes

PURPOSE

To assess the incidence of immunologic corneal graft rejection episodes in a prospective case series of patients treated 4 times a day with topical cyclosporine 0.05%.

DESIGN

Prospective, single-center, institutional review board-approved study.

PARTICIPANTS

Fifty-two cornea transplant recipients considered low risk for graft rejection.

METHODS

Primary indications for transplantation were keratoconus, Fuchs' dystrophy, or nonherpetic, nonvascularized scars. Subjects completely tapered off prednisolone acetate 1% by 13 weeks after transplantation and used topical cyclosporine 0.05% 4 times a day, beginning either 1 or 10 weeks posttransplant, with use continued until 1 year posttransplant. One subgroup supplemented cyclosporine use with pulsed prednisolone acetate 1% dosing, 4 times a day for 4 days every 6 weeks. The incidence of immunologic corneal graft rejection episodes was compared with that in Fuchs' and keratoconus historical control subjects, who used topical steroids a median of 7 months after penetrating keratoplasty.

MAIN OUTCOME MEASURE

Incidence of immunologic graft rejection episodes.

RESULTS

Graft rejection episodes occurred earlier and with higher incidence in subjects using cyclosporine 0.05% compared with historical control subjects who used steroids for a longer period of time (P<0.0001). Cyclosporine subjects who pulse-dosed prednisolone had a significantly higher incidence of graft rejection compared with those who did not pulse steroids (P = 0.04).

CONCLUSION

The results suggest that 4 times daily dosing with topical cyclosporine 0.05% is not as effective as use of topical prednisolone acetate 1% for prevention of graft rejection episodes in low-risk corneal transplants, and that periodic pulsing with corticosteroids may increase the risk of rejection episodes.

Safety and efficacy of cyclosporine 0.05% drops versus unpreserved artificial tears in dry-eye patients having laser in situ keratomileusis

PURPOSE

To evaluate dry-eye signs, symptoms, and refractive outcomes in patients with dry-eye disease having laser in situ keratomileusis (LASIK).

METHODS

In this randomized parallel double-masked prospective clinical trial, 42 eyes of 21 myopic patients (mean spherical equivalent -4.3 diopters [D], range -1.00 to -10.63 D) with dry-eye disease were treated with unpreserved artificial tears or cyclosporine 0.05% ophthalmic emulsion twice a day beginning 1 month before LASIK. Treatment with the study drug was discontinued for 48 hours post surgery and then resumed for 3 additional months. Both groups used additional artificial tears as needed. Study visits occurred pretreatment (baseline), before surgery, and at 1 week and 1, 3, 6, and 12 months after surgery.

RESULTS

Statistically significant increases from baseline were found in Schirmer scores for artificial tears at 1 month (P = .036) and for cyclosporine 0.05% before surgery and 1 week, 1 month, and 6 months after surgery (P<.018). There were no significant differences from baseline or between groups in responses to the Ocular Surface Disease Index questionnaire or best corrected visual acuity (BCVA), nor were there significant between-group differences in superficial punctate keratitis or uncorrected visual acuity. Mean refractive spherical equivalent in cyclosporine-treated eyes was significantly closer to the intended target at 3 and 6 months after surgery than in artificial-tears-treated eyes (P = .007). A greater percentage of cyclosporine eyes was within +/-0.5 D of the refractive target 3 months after surgery than artificial tears eyes (P = .015).

CONCLUSION

Successful outcomes after LASIK were achieved for dry-eye disease patients. Treatment with cyclosporine 0.05% provided greater refractive predictability 3 and 6 months after surgery than unpreserved artificial tears.

Mucins and TFF peptides of the tear film and lacrimal apparatus

The three-dimensional organization of the tear film, which is produced and drained by the different structures of the ocular adnexa, is essential for maintainance and protection of the ocular surface. This is facilitated by a class of large, highly glycosylated, hydrophilic glycoproteins, the mucins, which are usually expressed in association with a class of peptides having a well-defined, structurally conserved trefoil domain, the mammalian trefoil factor family (TFF) peptides. In this review, the latest information regarding mucin and TFF peptide function and regulation in the human lacrimal system, the tear film and the ocular surface is summarized with regard to mucous epithelia integrity, rheological and antimicrobial properties of the tear film and tear outflow, age-related changes and certain disease states such as dry eye, dacryostenosis and dacryolith formation.

Sensory denervation modulates eIF-2 alpha kinase expression in the rabbit lacrimal gland

PURPOSE

To investigate the hypothesis that sensory denervation of the rabbit lacrimal gland results in dysregulation of protein synthesis. We used differential display of mRNA to identify genes associated with protein synthesis and secretion that may be altered in this situation.

METHODS

New Zealand white rabbits underwent unilateral sensory denervation by the ablation of the trigeminal ganglion. After 7 days, the denervated and contralateral control lacrimal glands were removed. The effects of denervation on gene expression were carried out using differential mRNA display. Northern and Western blot analyses were used to verify differential gene expression.

RESULTS

Differential mRNA display identified the gene heme-regulated inhibitor eukaryotic initiation factor-2 alpha kinase (HRI eIF-2a kinase) in the lacrimal gland, the expression of which was reduced in the denervated lacrimal gland. The sequenced fragment from differential display showed 94% identity to rabbit HRI eIF-2a kinase. The decreased expression of HRI eIF-2a kinase was confirmed by Northern and Western blots, and measurement of HRI eIF-2a kinase phosphorylation activity in the lacrimal gland after ablation of sensory neurons showed that it was significantly decreased compared with that of normal and control lacrimal glands.

CONCLUSIONS

The results suggest that loss of sensory innervation has a role in the lacrimal gland, contributing to the expression of HRI eIF-2a kinase, a pivotal negative regulator of protein synthesis. A reduction in control of protein synthesis may lead to the translation of repressed messages associated with cell stress responses.

Proteomic analysis of human meibomian gland secretions

BACKGROUND/AIM

Human tears contain hundreds of proteins that may exert a significant influence on tear film stability, ocular surface integrity, and visual function. The authors hypothesise that many of these proteins originate from the meibomian gland. This study's aim was to begin to develop the proteomic methodology to permit the testing of their hypothesis.

METHODS

Meibomian gland secretions were collected from the lower eyelids of adult volunteers and placed in a chloroform-methanol mixture. Samples were partitioned in a biphasic system and non-lipid phase materials were reduced, alkylated, and trypsin digested to obtain peptides for protein identification. This peptide mixture was separated by micro-capillary reverse phase chromatography and the effluent examined by nano-electrospray MS and data dependent MS/MS. SEQUEST software was used to identify proteins from the MS/MS spectra.

RESULTS

The methodological approach to date has permitted the identification of more than 90 proteins in human meibomian gland secretions. Proteins include the alpha2-macroglobulin receptor, IgA alpha chain, farnesoid X activated receptor, interferon regulatory factor 3, lacritin precursor, lactotransferrin, lipocalin 1, lysozyme C precursor, potential phospholipid transporting ATPase IK, seven transmembrane helix receptor (also termed somatostatin receptor type 4), testes development related NYD-SP21 (also termed high affinity IgE receptor beta subunit), and TrkC tyrosine kinase.

CONCLUSIONS

These findings indicate that the meibomian gland secretes a number of proteins into the tear film. It is quite possible that these proteins contribute to the dynamics of the tear film in both health and disease.

The Th1/Th2 paradigm in ocular allergy

PURPOSE OF REVIEW

The paradigm that diseases are either Th1 mediated or Th2 mediated has recently been challenged in a number of classical ocular diseases. The objective of this article is to highlight the importance of understanding the exact mechanisms of Th1 and Th2 cells in the pathology of ocular allergy.

RECENT FINDINGS

Current research of Th1 and Th2 cytokines in an animal model of ocular allergy demonstrates the intricate complex regulation by both subsets of cytokines of the disease process. Th2 prone BALB/c wild type mice sensitized and topically challenged with short ragweed for seven consecutive days (multi-hit) developed a sustained, chronic conjunctival inflammation. Significantly, IFN-gamma knockout mice in the multi-hit antigen challenge model had a reduced conjunctival cellular infiltrate. Evaluation of adhesion molecules that actively regulate cellular infiltration into the conjunctiva revealed a lack of vascular cell adhesion molecule-1 in multi-hit antigen challenged IFN-gamma knockout mice.

SUMMARY

Recent ocular allergy studies question the Th1/Th2 paradigm. These studies encourage further understanding of the intricate interactions of Th1 and Th2 cytokines in ocular inflammatory disease. The following components of Th1 and Th2 cells in the development of chronic inflammation associated with allergic conjunctivitis will be discussed: T helper subsets Th1 and Th2 in ocular inflammation, activation of T cells in the lymph node, and the role of IFN-gamma as the endothelium gatekeeper in the pathology of Th2-mediated allergic conjunctivitis.

Desiccating Stress Induces T Cell-Mediated Sjögren’s Syndrome-Like Lacrimal Keratoconjunctivitis

Chronic dry eye syndrome affects over 10 million people in the United States; it is associated with inflammation of the lacrimal gland (LG) and in some cases involves T cell infiltration of the conjunctiva. We demonstrate that environmental desiccating stress (DS) elicits T cell-mediated inflammation of the cornea, conjunctiva, and LG, but not other organs in mice. The lacrimal keratoconjunctivitis (LKC) was mediated by CD4(+) T cells, which, when adoptively transferred to T cell-deficient nude mice, produced inflammation in the LG, cornea, and conjunctiva, but not in any other organ. Adoptively transferred CD4(+) T cells produced LKC even though recipients were not exposed to DS. LKC was exacerbated in euthymic mice depleted of CD4(+)CD25(+)forkhead/winged helix transcription factor(+) regulatory T cells. The results suggest that DS exposes shared epitopes in the cornea, conjunctiva, and LG that induce pathogenic CD4(+) T cells that produce LKC, which under normal circumstances is restrained by CD4(+)CD25(+)forkhead/winged helix transcription factor(+) regulatory T cells.

Changes in corneal and conjunctival sensitivity, tear film stability, and tear secretion after strabismus surgery

PURPOSE

Some patients complain of a foreign body sensation, a burning sensation, or dryness after strabismus surgery. We prospectively investigated the changes in corneal and conjunctival sensitivity, tear film stability, and tear secretion after strabismus surgery.

PATIENTS AND METHODS

Corneal and conjunctival sensitivity were assessed with an esthesiometer, tear film breakup time was measured, and the Schirmer test was performed prospectively (preoperatively and 1 week, 1 month, and 3 months postoperatively) in 83 patients (124 eyes) who underwent strabismus surgery at our institution.

RESULTS

There were no significant changes in corneal sensitivity, tear film stability, or tear secretion after strabismus surgery (P > .05). Conjunctival sensitivity decreased significantly after strabismus surgery (P < .05).

CONCLUSION

Discomfort and dryness after strabismus surgery do not seem to be related to changes in corneal sensitivity, tear film stability, or tear secretion.

Cell and molecular biology of human lacrimal gland and nasolacrimal duct mucins

The old concept that the lacrimal gland is only a serous gland has been superseded by the finding that lacrimal acinar cells are able to produce mucins--high-molecular-weight proteins--the major mass being carbohydrates with the common feature of tandem repeats of amino acids rich in serine, threonine, and proline in the central domain of the mucin core peptide. At the ocular surface, maintenance of the tear film, lubrication, and provision of a pathogen barrier on the epithelia, conjunctiva, and cornea have been shown to be facilitated by mucins that are present in membrane-anchored (lining epithelial cells) or secreted (goblet cells) form. Also in the lacrimal gland, both membrane-anchored (MUCs 1, 4, and 16) and secreted (MUCs 5B and 7) mucins have been identified. The lacrimal gland is the main contributor to the aqueous portion of the tear film. It is part of the lacrimal apparatus that comprises, together with the lacrimal gland, the paired lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, which collects the tear fluid and conveys it into the nasal cavity. In this review, the latest information regarding mucin function in the human lacrimal gland and the human efferent tear ducts is summarized with regard to mucous epithelia integrity, rheological and antimicrobial properties of the tear film and tear outflow, age-related changes, and certain disease states such as the pathogenesis of dry eye, dacryostenosis, and dacryolith formation.