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

Up-regulated gene expression in the conjunctival epithelium of patients with Sjögren's syndrome

PURPOSE

To elucidate the pathogenesis of ocular surface abnormalities in patients with Sjögren's syndrome (SS) by comparing global gene expression patterns in conjunctival epithelial cells from normal individuals and SS patients.

METHODS

The study population consisted of 56 subjects (26 SS patients and 30 normal volunteers). RNA extracted from their conjunctival epithelial cells was subjected to introduced amplified fragment length polymorphism (iAFLP), a competitive PCR-based gene expression assay, to measure gene expression in the 56 samples against 931 genes. Data were analyzed by two-dimensional clustering analysis and discriminant analysis. Disease-related genes were identified and the feasibility of gene expression-based diagnosis of SS was examined.

RESULTS

Two-dimensional clustering- and discriminant analysis clearly distinguished between SS patients and normal subjects. Of 931 genes tested, 34 were significantly up-regulated and 12 were significantly down-regulated in SS (p<0.05). Up-regulated genes included kallikrein 7 (x 15.8) and small proline-rich protein 2A (x 9.6), markers for the terminal differentiation of epidermis, and the inflammation-related genes HLA-DR and IL-6. Monokine-induced-by-gamma-interferon, i.e. c-fos, fibronectin, amphiregulin, defensin beta 2, and keratin 16, -6b and -6c were also up-regulated. Among the 12 down-regulated genes, interferon-gamma receptor 1 was most notable (x1/27.3).

CONCLUSIONS

The up-regulated expression of keratin 6 and -16, small proline-rich protein 2A, and kallikrein 7 in the conjunctival epithelium of SS patients suggests an anomalous keratinization pattern. Epithelial thickening may be due to amphiregulin and/or c-fos-stimulated cell cycle progression. The up-regulation of monokine-induced-by-gamma-interferon, HLA-DR, keratin 6b, -6c, and -16 suggests that in SS, interferon-gamma may play an important role in the altered gene expression in the conjunctival epithelium.

Induction of nitric oxide synthase and over-production of nitric oxide by interleukin-1beta in cultured lacrimal gland acinar cells

PURPOSE

Inflammation of the lacrimal gland is one of the major causative factors in aqueous tear-deficient dry eye syndrome. Pro-inflammatory cytokine production is upregulated in lacrimal gland autoimmune disease (i.e. Sjögren's syndrome) and is associated with cell death. The expression of inducible nitric oxide synthase (iNOS/NOS-2) is known to be induced in the presence of pro-inflammatory cytokines in several secretory epithelial cell types. We hypothesize that pro-inflammatory cytokines, such as interleukin-1beta (IL-1beta), cause a marked increase in nitric oxide (NO) production via induction of iNOS in lacrimal gland epithelial cells and that this may be a significant pathophysiological pathway of dry eye syndrome.

METHODS

Cultured immortalized rabbit lacrimal gland acinar cells were incubated with IL-1beta, iNOS inhibitor, or IL-1 receptor antagonist (IL-1ra). Colorimetric detection of NO(2)(-) and NO(3)(-) in the media, measured by the Griess reaction, was used as an index of NO production. Expression of iNOS was determined by SDS-PAGE and Western blot.

RESULTS

IL-1beta stimulated a concentration-dependent and time-dependent increase in NO production. IL-1beta-induced NO production was significantly antagonized by co-incubation with IL-1ra or the iNOS-specific inhibitor, 1400W. Expression of iNOS protein was greatest at 4hr after addition of IL-1beta, and was nearly undetectable at 12hr. IL-1ra greatly reduced IL-1beta-induced iNOS expression.

CONCLUSIONS

Lacrimal gland acinar cells are able to produce iNOS in response to the pro-inflammatory cytokine IL-1beta. The amount of iNOS expressed and the subsequent levels of NO that are produced by lacrimal cells are far lower than those seen in macrophages, but are consistent with those reported for other cell types in the literature. This pathway of iNOS induction and overproduction of NO may be a factor in lacrimal gland cell death in dry eye syndrome. Inhibitors of iNOS or IL-1 receptor may be beneficial for controlling lacrimal gland inflammation.

The effect of hinge position on corneal sensation and dry eye after LASIK

PURPOSE

To investigate the effect of hinge position on corneal sensation and dry eye syndrome after laser in situ keratomileusis (LASIK).

DESIGN

Prospective, randomized, self-controlled trial.

PARTICIPANTS

Fifty-two patients >/=18 years of age undergoing bilateral LASIK.

INTERVENTION

Patients underwent bilateral LASIK with the superior-hinge Hansatome microkeratome in one eye and the nasal-hinge Amadeus microkeratome in the other eye. In all eyes, the flaps were 160 micro m thick, with a diameter of 9.5 mm.

MAIN OUTCOME MEASURES

Masked Cochet-Bonnet esthesiometry was performed centrally before surgery and at 1 week, 1 month, 3 months, and 6 months after surgery. Dry eye was evaluated at the same time intervals with lissamine green corneal and conjunctival staining, Schirmer testing with anesthesia, and tear-film breakup time. Subjective evaluation of dry eye sensation was performed at 3 and 6 months after surgery.

RESULTS

Corneal sensation was reduced in eyes with either superior- or nasal-hinge corneal flaps at 1 week, 1 month, and 3 months after surgery (P < 0.001). Compared with preoperative values, a significant reduction in corneal sensation remained at 6 months in corneas with superior-hinge flaps (P < 0.001) but not in corneas with nasal-hinge flaps (P = 0.263). Mean corneal sensation was greater in corneas with a nasal-hinge flap compared with corneas with a superior-hinge flap at all postoperative visits (P < 0.001). The loss of sensation was greatest at 1 week and showed improvement at each subsequent time interval up to 6 months. Overall, dry eye signs and symptoms were greatest during the immediate postoperative period and improved at all subsequent time intervals. Dry eye signs and symptoms were generally greatest in the eyes with a superior-hinge flap and milder in eyes with a nasal-hinge flap.

CONCLUSIONS

The long posterior corneal nerves, which innervate the cornea, enter the eye at 3- and 9-o'clock. A superior-hinge flap transects both arms of the neuroplexus, whereas a nasal hinge transects only the temporal arm. LASIK results in a significant reduction in corneal sensation. Corneal sensation and dry eye signs and symptoms decreased immediately after LASIK and improved at all time periods between 1 week and 6 months in eyes with both a nasal-hinge flap and a superior-hinge flap. However, the loss of corneal sensation and presence of dry eye syndrome were greater in eyes with a superior-hinge flap than in eyes with a nasal-hinge flap.

Corneal nerves: structure, contents and function

This review provides a comprehensive analysis of the structure, neurochemical content, and functions of corneal nerves, with special emphasis on human corneal nerves. A revised interpretation of human corneal nerve architecture is presented based on recent observations obtained by in vivo confocal microscopy (IVCM), immunohistochemistry, and ultrastructural analyses of serial-sectioned human corneas. Current data on the neurotransmitter and neuropeptide contents of corneal nerves are discussed, as are the mechanisms by which corneal neurochemicals and associated neurotrophins modulate corneal physiology, homeostasis and wound healing. The results of recent clinical studies of topically applied neuropeptides and neurotrophins to treat neurotrophic keratitis are reviewed. Recommendations for using IVCM to evaluate corneal nerves in health and disease are presented.

Blood concentrations of cyclosporin a during long-term treatment with cyclosporin a ophthalmic emulsions in patients with moderate to severe dry eye disease

To quantify blood cyclosporin A (CsA) concentrations during treatment with CsA topical ophthalmic emulsions, blood was collected from 128 patients enrolled in a Phase 3, multicenter, double-masked, randomized, parallel-group study of CsA eyedrops for treatment of moderate to severe dry eye disease. Patients received 0.05% CsA, 0.1% CsA, or vehicle b.i.d. for 6 months; vehicle-treated patients then crossed over to 0.1% CsA b.i.d. for 6 months. CsA concentrations were measured using a validated LC/MS-MS assay (quantitation limit = 0.1 ng/mL). No patient receiving 0.05% CsA had any quantifiable CsA in the blood (n = 96 samples). All but 7 of 128 (5.5%) trough blood samples from the 0.1% CsA group were below the quantitation limit for CsA; none exceeded 0.3 ng/mL. CsA was also below the limit of quantitation in 205 of 208 (98.6%) of serial postdose blood samples collected from 26 patients during 1 dosing interval between months 9 and 12. The highest C(max) measured, 0.105 ng/mL at 3 hours postdose, occurred in a 0.1% CsA-treated patient. These results indicate that long-term use of topical CsA ophthalmic emulsions at doses that are clinically efficacious for treating dry eye will not cause any system-wide effects.

Nitric oxide and cyclic GMP-mediated protein secretion from cultured lacrimal gland acinar cells

PURPOSE

Nitric oxide (NO) donors and NO synthase (NOS) substrates were tested for their use to stimulate protein secretion from cultured lacrimal gland acinar cells, through activation of guanylate cyclase.

METHOD

Rabbit lacrimal gland epithelial cells (RLG cells) were incubated with NO donors and/or NOS substrates and the protein released into culture medium was determined with bicinchoninic acid assay. Guanylate cyclase activation by NO precursors was determined by measurement of c-GMP produced.

RESULTS

Both NO donors and NOS substrates were able to stimulate protein release from RLG cells. Among 6 compounds studied, sodium nitroprusside, isosorbide dinitrate and N(a)-benzoyl L-arginine ethyl ester (BAEE) were most potent to release protein over 100% of the basal release. The guanylate cyclase activity was stimulated by these NO precursors and was inhibited by guanylate cyclase inhibitor, [1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ).

CONCLUSION

NO donors and NOS substrates were able to stimulate protein release from RLG cells via activation of guanylate cyclase and c-GMP release, which was blocked by guanylate cyclase inhibitor, ODQ. It indicates that NO donors and NOS substrates could be used for the treatment of dry eye syndrome if the same holds true in dry eye animal models.

Topical cannabinoid agonist, WIN55,212-2, reduces cornea-evoked trigeminal brainstem activity in the rat

Cannabinoids act at receptors on peripheral and central neurons to modulate diverse physiological functions and produce analgesia. Corneal sensory nerves express the CB1 cannabinoid receptor and project to two spatially discrete regions of the lower brainstem, the trigeminal interpolaris/caudalis (Vi/Vc) transition and subnucleus caudalis/upper cervical cord (Vc/C1) junction region. The function of CB1 expression on corneal nerves is not known. To determine if cannabinoid receptors in the anterior eye affect the activity of trigeminal brainstem neurons at the Vi/Vc and Vc/C1 the CB1 agonist, WIN55,212-2 (WIN-2), was applied topically prior to chemical excitation of corneal afferent fibers. In the first series of experiments WIN-2 was applied topically prior to excitation of corneal nociceptors by mustard oil (MO). WIN-2 reduced significantly the number of Fos-like immunoreactive neuronal nuclei (Fos-LI) at the Vi/Vc transition (-46.7+/-8.2%, P<0.05), while smaller non-significant reductions occurred at the Vc/C1 junction region (-20.3+/-7.6%). The selective CB1 antagonist, SR141716A (1mg/kg, i.v.), prevented WIN-2-evoked reduction in Fos-LI after MO. Systemic administration of WIN-2 (1 or 10mg/kg, i.p.) or SR141716A (1mg/kg, i.v.) or topical corneal application of morphine sulfate did not affect Fos-LI produced by MO. In parallel experiments, topical WIN-2 reduced the magnitude of single unit activity recorded at the Vi/Vc transition (-80+/-7%, P<0.025), but not at the Vc/C1 junction region (-34+/-30%) evoked by CO(2) pulses applied to the cornea. Topical morphine did not alter CO(2)-evoked unit activity at either recording location. These results indicated that cannabinoid receptor agonists acted, at least in part, at CB1 receptors in the anterior eye to reduce corneal stimulation-evoked trigeminal brainstem neural activity. Corneal nociceptor-evoked activity at the Vi/Vc transition was reduced significantly by topical WIN-2, while activity at the Vc/C1 junction region displayed only minor decreases. These findings were consistent with the hypothesis that CB1 receptors affect the activity of corneal-responsive neurons that preferentially contribute to homeostasis of the anterior eye and/or reflexive aspects of nociception rather than the sensory-discriminative aspects of corneal nociception.

Topical nonsteroidal anti-inflammatory drugs for ophthalmic use: a safety review

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used agents that despite chemically heterogeneity, share similar therapeutic properties and adverse effects. Topical ophthalmic NSAIDs are limited to the relatively water soluble phenylacetic and phenylalkanoic acids as well as indole derivatives, which are more suitable for ophthalmic use. Topical ophthalmic NSAIDs are commonly used in the treatment of post-operative inflammation following cataract extraction and various surgical refractive procedures. They are also used in the prevention and treatment of cystoid macular oedema and for the treatment of allergic conjunctivitis. Absorption of topical ophthalmic NSAIDs through the nasal mucosa results in systemic exposure and the occurrence of adverse systemic events, including exacerbation of bronchial asthma. Local irritant effects of topical ophthalmic NSAIDs include conjunctival hyperaemia, burning, stinging and corneal anaesthesia. A more serious complication involves the association of topical ophthalmic NSAIDs with indolent corneal ulceration and full-thickness corneal melts. Analysis of NSAID-associated corneal events implicates the now defunct generic dicolfenac product, diclofenac sodium ophthalmic solution as the agent primarily responsible. However, these events generated a renewed interest in the safety of ophthalmic NSAIDs and a scrutiny of the pharmacology regarding NSAID action in the eye. An elucidation of possible pharmacodynamic explanations of NSAID-induced corneal injury includes the role of epithelial hypoxia, which not only appears to aid in determining the metabolic destination of arachidonate, it may play a key role in orchestrating a novel inflammatory response unrelated to prostanoid formation. The use of NSAIDs under conditions of corneal hypoxia may therefore not only result in a disappointing therapeutic response, it may result in a paradoxical inflammatory exacerbation. Other potential mechanisms include the relationship between NSAIDs and corneal matrix metalloproteinase and direct toxicity due to cytotoxic excipients such as surfactants, solubilisers and preservatives found in topical NSAID ophthalmic preparations. In general, ophthalmic NSAIDs may be used safely with other ophthalmic pharmaceuticals; however, concurrent use of agents known to adversely effect the corneal epithelium, such as gentamicin, may lead to increased corneal penetration of the NSAID. The concurrent use of NSAIDs with topical corticosteorids in the face of significant pre-existing corneal inflammation has been identified as a risk factor in precipitating corneal erosions and melts and should be undertaken with caution. Until clinical evidence dictates otherwise, data supporting theories of potential pharmacodynamic mechanisms of NSAID injury do not alter the favorable benefit-risk ratio of ophthalmic NSAID use when employed in an appropriate and judicious manner.

Ocular allergy guidelines: a practical treatment algorithm

The treatment of ocular allergy requires a better understanding of the spectrum of clinical disorders involving various components of the immune system, and of interactions at the conjunctival surface. The immune response focuses primarily on the different levels of activity of Th2 lymphocytes and various other immune cells associated with allergic disorders, including mast cells, eosinophils, fibroblasts, and epithelial and endothelial cells. Ocular allergic disorders include seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC), vernal keratoconjunctivitis (VKC), giant papillary conjunctivitis (GPC) and atopic keratoconjunctivitis (AKC), which, through immunopathological and molecular immunological techniques, can all be better appreciated as being part of a larger spectrum of an atopic disease state. In SAC, pathological changes, such as increased mast-cell activation, the presence of migratory inflammatory cells, and early signs of cellular activation at the molecular level, are minimal. In PAC, these changes are more pronounced in line with the increased duration of allergenic stimulation. In more chronic forms of allergic conjunctivitis, such as VKC in children and AKC in adults, the following changes are evident: a persistent state of mast cell, eosinophil and lymphocyte activation; noted switching from connective-tissue to mucosal-type mast cells; increased involvement of corneal pathology; and follicular development and fibrosis. The treatment of acute and more chronic forms of allergic conjunctivitis has focused in the past on symptomatic relief of symptoms, but with a better understanding of the mechanisms involved we can now provide interventional therapeutic strategies and symptomatic relief. Our advances in the basic understanding of these conditions are providing the foundation for guidelines that improve the ocular health of patients with ocular allergies.

Sodium hyaluronate eye drops of different osmolarity for the treatment of dry eye in Sjögren's syndrome patients

AIM

To study the effect of the treatment of dry eye in Sjögren's syndrome patients with hypotonic or isotonic hyaluronate eye drops.

METHODS

40 Sjögren's syndrome patients were divided in two groups and treated as follows: group 1 with hypotonic (150 mOsm/l) 0.4% hyaluronate eye drops; group 2 with isotonic 0.4% hyaluronate eye drops. The eye drops were instilled six times a day for 90 days. Grading of subjective symptoms, break up time (BUT), corneal fluorescein staining, conjunctival rose bengal staining, Schirmer's I test, and conjunctival impression cytology were carried out at 0 and 15, 30, 90 days from the beginning of the study. Patients were examined in a blind fashion. For the statistical analysis the Student's t test, Mann-Whitney U test, and chi(2) test were performed.

RESULTS

Symptoms were statistically significantly improved at day 15 in both groups but group 1 patients had a global score statistically significantly better group 2 (p=0.02). At day 15 group 1 patients had an improvement from baseline values of BUT (p=0.003), fluorescein, and rose bengal score (p=0.000001 and p=0.0004 respectively). Group 2 patients had, at day 15, an improvement of BUT and fluorescein score compared to baseline values (p=0.05 and p=0.0001 respectively). A comparison between the two groups showed better results for group 1 patients at day 15 for rose bengal stain (p=0.01) and for BUT (p=0.05) and fluorescein score (p=0.0003) at day 90. The conjunctival impression cytology showed that group 1 had a statistically significant better total score than group 2 starting from day 15 and lasting throughout the study (p<0.02). Also group 2 patients showed an improvement from baseline values starting from day 30 (p=0.000005).

CONCLUSION

Hyaluronate eye drops are useful for treating severe dry eye in Sjögren's syndrome patients. The use of a formulation with pronounced hypotonicity showed better effects on corneoconjunctival epithelium than the isotonic solution.

Histologic characteristics and local cellular immunity of the gland of the third eyelid after topical ophthalmic administration of 2% cyclosporine for treatment of dogs with keratoconjunctivitis sicca

OBJECTIVE

To evaluate the efficacy of topical administration of a 2% solution of cyclosporine (CsA) for treatment of dogs with keratoconjunctivitis sicca (KCS) and to correlate results with histopathologic characteristics and local cellular immunity of the gland of the third eyelid.

ANIMALS

24 dogs with bilateral KCS.

PROCEDURE

Lacrimal secretion was measured, using Schirmer tear test (STT) strips. Leukocyte and T-lymphocyte subsets were determined in blood samples. Histopathologic changes as well as CD4+, CD8+, and alpha-naphthyl-acetate esterase-positive (ANAE+) lymphocytes were evaluated.

RESULTS

Clinical signs resolved at the end of 1 month in conjunction with significantly increased STT values, compared with baseline values. Fifteen and 30 days after discontinuation of CsA treatment, a decrease was observed in STT values in both eyes; however, only values for the right eye were significantly different. There was a significant decrease in the number of lymphocytes and ANAE+ lymphocytes 15 and 30 days after discontinuation of CsA treatment, compared with baseline values. Differences were not observed in number of CD4+ lymphocytes among treatment groups. However, there was a significant decrease in number of CD8+ lymphocytes with reversal of the CD4+:CD8+ in both eyes after CsA treatment for 30 days, compared with the control group. Increased secretory activity and decreased lymphocyte infiltration were characteristic histopathologic findings.

CONCLUSIONS AND CLINICAL RELEVANCE

Topical administration of a 2% solution of CsA was effective for the treatment of dogs with KCS. Strict follow-up monitoring is required after the cessation of treatment because of the possibility of recurrence of KCS.

Effect of Laser in situ Keratomileusis for Hyperopia on Tear Film and Ocular Surface

PURPOSE

To examine the effects of laser in situ keratomileusis (LASIK) for hyperopia on the tear film and ocular surface.

METHODS

A retrospective 12-month analysis of 88 eyes (88 participants) who had LASIK for hyperopia was performed. Participants were evaluated before and after (2 weeks, 1, 3, 6, and 12 months) surgery for dry eye symptoms (McMonnies Dry Eye Survey primary symptoms), tear film stability (fluorescein break-up time), tear volume (phenol red thread test), ocular surface staining (fluorescein), and conjunctival goblet cell density.

RESULTS

Chronic dry eye was experienced by 32% of participants; symptoms were significantly associated with female gender, preoperative dry eye symptoms, lower tear film stability after surgery, greater ocular surface staining after surgery, lower tear volume before and after surgery, and lower goblet cell densities after surgery. Regression rate 12 months after surgery was 32% and significantly associated with female gender, chronic dry eye symptoms, lower tear film stability after surgery, greater ocular surface staining before and after surgery, and lower tear volume before and after surgery.

CONCLUSIONS

Dry eye, particularly in females, is problematic after LASIK for hyperopia and is associated with refractive regression. Current methods for managing the tear film and ocular surface may not control LASIK-induced dry eye, particularly in some females during the first 6 months after surgery.

Long term treatment with sodium hyaluronate-containing artificial tears reduces ocular surface damage in patients with dry eye

BACKGROUND/AIMS

Several studies have reported that sodium hyaluronate is able to improve both symptoms and signs in patients with dry eye but none have demonstrated an improvement of conjunctival epithelial cell abnormalities of the ocular surface. The aim of this study was to explore the effect of sodium hyaluronate-containing eye drops on the ocular surface of patients with dry eye during long term treatment.

METHODS

A randomised double blind study was undertaken in 86 patients with medium to severe dry eye (that is, rose bengal and/or fluorescein test score of at least 3, tear film break up time <10 seconds, or Schirmer's test <5.5 mm). Patients were treated with either preservative-free sodium hyaluronate or saline for 3 months at a dose of one drop 4-8 times a day. Bulbar impression cytology, slit lamp examinations, and subjective symptoms were evaluated after 1, 2, and 3 months. Impression cytology was considered the primary efficacy parameter of the study.

RESULTS

The efficacy analysis was performed on a total of 44 patients who were able to fully adhere to the protocol. After 3 months of treatment sodium hyaluronate improved impression cytology score (p = 0.024 v baseline). At the same time also the difference with respect to placebo was statistically significant (p = 0.036). Study medication was well tolerated and no treatment related adverse events occurred during the study.

CONCLUSIONS

Sodium hyaluronate may effectively improve ocular surface damage associated with dry eye syndrome.

Dry eye in the elderly

Dry eye in the elderly population is a condition with a multitude of contributing factors and a wide spectrum of severity. The complex tear film is made up of layers of oil, aqueous and mucin, produced by the meibomian glands, main and accessory lacrimal glands, and by the goblet cells, respectively. Alteration in the normal function of any of these structures by disease, trauma or the environment can cause dysfunction of the tear film and result in the symptoms of dry eye (such as burning, grittiness and blurred vision). Normal lid anatomy and closure is critical to prevent evaporation of the normal tear film. The mainstay of current therapy is augmentation of the tear film with artificial tears and ointment. More severe cases of dry eye may require occlusion of the tear drainage system with plugs or electrocautery scarring. Good lid hygiene is also important for tear film health. A new paradigm of dry eye as a subclinical inflammatory disease has recently been suggested, and preliminary results from treatment with topical cyclosporin formulations are encouraging. The next few years promise exciting advances and relief for patients suffering from this chronic condition.

Prevalence of treated dry eye disease in a managed care population

BACKGROUND

Survey studies are of limited utility in estimating the prevalence of treated dry eye. The use of claims data, which include only individuals who have a diagnosis of the disorder, provides a better estimation of the clinical significance of dry eye symptoms and appraisal of community needs.

OBJECTIVE

The purpose of this paper is to estimate the prevalence of treated dry eye disease using a nonsurvey methodology.

METHODS

Patients with dry eye diagnoses or who underwent punctal occlusion procedures were identified from PharMetrics' Integrated Outcomes database of medical claims for approximately 10 million patients enrolled in managed care plans. Prevalence estimates were calculated for 1997 and 1998.

RESULTS

The prevalence of dry eye was 0.48% in 1997 and 0.39% in 1998, representing 25,180 and 27,289 cases, respectively. Patients aged > or = 65 years were approximately 4 times as likely as those aged < 65 years to be diagnosed with keratoconjunctivitis sicca or tear film insufficiency. In 1997, dry eye was diagnosed or treated in 0.65% of women compared with 0.26% of men (P < 0.001). Rates of dry eye disease in 1998 were highest among women aged 75 to 79 years (2.02%) and men aged 80 to 84 years (1.30%). Women tended to receive a diagnosis at a younger age than did men. The most common diagnosis was tear film insufficiency (73.96% and 73.41% of dry eye patients in 1997 and 1998, respectively). The most common procedure was lacrimal punctal occlusion by plug (7.78% and 8.74% of dry eye patients in 1997 and 1998, respectively).

CONCLUSION

The prevalence of treated dry eye disease is 0.4% to 0.5% and is highest among women and the elderly.

Sjögren's syndrome as seen by an ophthalmologist

Ocular surface involvement is a frequent feature of Sjögren syndrome characterized by the presence of typical symptoms such as burning and foreign body sensation and by wide spread epithelial damage of the cornea and on the conjunctiva. There is now evidence that local inflammatory changes and lacrymal gland-derived tear-borne pro-inflammatory agents have an important role in the build up and the maintenance, of ocular surface damage by the instauration of self maintaining vicious cycles. Inflammation causing decreased ocular surface sensation, resulting in further decreased tear secretion and decreased tear clearance, with growing concentration of pro inflammatory agents on the ocular surface. From the anatomic pathological point of view there is a not clarified discrepancy between the early highly depressed tear fluid production and the limited extension of involvement of the lacrymal gland. Proper gland stimulatory agents and control of inflammation could result in a better treatment than the palliative therapy available to day.

Chitosan nanoparticles: a new vehicle for the improvement of the delivery of drugs to the ocular surface. Application to cyclosporin A

Present limitations in the management of extraocular diseases include the inability to provide long-term extraocular drug delivery without compromising intraocular structures and/or systemic drug exposure. In the present study, the potential of chitosan (CS) nanoparticles as a new vehicle for the improvement of the delivery of drugs to the ocular mucosa was investigated. Cyclosporin A (CyA) was chosen as a model compound because of its potential usefulness for the treatment of these local diseases. An ionic gelation technique was conveniently modified in order to produce CyA-loaded CS nanoparticles. These nanoparticles had a mean size of 293 nm, a zeta potential of +37 mV and high CyA association efficiency and loading (73 and 9%, respectively). In vitro release studies, performed under sink conditions, revealed a fast release during the first hour followed by a more gradual drug release during a 24-h period. In vivo experiments showed that, following topical instillation of CyA-loaded CS nanoparticles to rabbits, it was possible to achieve therapeutic concentrations in external ocular tissues (i.e., cornea and conjunctiva) during at least 48 h while maintaining negligible or undetectable CyA levels in inner ocular structures (i.e., iris/ciliary body and aqueous humour), blood and plasma. These levels were significantly higher than those obtained following instillation of a CS solution containing CyA and an aqueous CyA suspension. From these results, we can conclude that CS nanoparticles may represent an interesting vehicle in order to enhance the therapeutic index of clinically challenging drugs with potential application at extraocular level.

Dry eye after refractive surgery

Photorefractive keratectomy and laser in situ keratomileusis can induce or exacerbate dry eye after surgery. This manifests as an increase in degree and frequency of symptoms, corneal findings, such as superficial punctate keratopathy, and abnormal results of dry eye tests, such as the Schirmer test and tear break-up time. The cause mainly involves decreased corneal sensation, resulting in decreased feedback to the lacrimal gland and reduced tear production. Other causes may include increased evaporation, inflammation, or toxicity of medications. Dry eye may result infrequently in impaired wound healing and decreased optical quality of the cornea, but it is transient, lasting from a few weeks up to 1 year. Patients should be warned about this distressing complication. During a period of dry eye, artificial tears and punctal plugs are helpful in preventing or alleviating patient discomfort.

Effects of laser in situ keratomileusis on tear production, clearance, and the ocular surface

PURPOSE

To evaluate components of the integrated ocular surface/lacrimal gland unit in a series of patients before and after undergoing bilateral laser in situ keratomileusis (LASIK).

DESIGN

Prospective, noncomparative case series.

PARTICIPANTS

Forty-eight eyes of 14 men and 34 women (age range, 26-54; mean, 39.2 years) who underwent bilateral LASIK for myopia or myopic astigmatism.

METHODS

LASIK was performed using a VISX Star Excimer Laser (Santa Clara, CA). Patients completed a questionnaire containing 11 questions that evaluated the character and severity of ocular irritation symptoms. Snellen visual acuity, tear fluorescein clearance, corneal fluorescein staining, aqueous tear production by the Schirmer 1 test, and corneal and conjunctival sensitivity were measured in each eye. Corneal surface regularity (SRI) was evaluated with the Tomey TMS-1 (Tomey, Cambridge, MA) topography instrument. Each randomly chosen eye was evaluated 1 to 2 days (T0) before LASIK and 7 days (T1), 1 (T2), 2 (T3), 6 (T4), 12 (T5), and 16 (T6) months postoperatively. A Wilcoxon test, two-tailed paired t test, Friedman test, or analysis of variance were used for statistical comparisons.

MAIN OUTCOME MEASURES

Components of the integrated ocular surface/lacrimal gland unit.

RESULTS

Both corneal and conjunctival sensitivity were noted to be significantly decreased from preoperative levels at 1week, 1 month, 12 months, and 16 months postoperatively (P < 0.0002 at each time point). Symptom severity scores were significantly increased at 1 week, 12 months, and 16 months postoperatively (P < 0.007 at all time points). The mean Schirmer 1 test scores were 24 +/- 14 mm preoperatively, and they decreased to 18 +/- 14 mm by 1 month postoperatively (P < 0.001). Tear fluorescein clearance showed a linear increase postoperatively and was significantly greater than baseline (P < 0.001) at each time point. There was a significant increase in punctate corneal fluorescein staining at 1 week postoperatively (P < 0.0001), but staining returned to baseline by 12 months. There was a statistically significant increase in SRI 1 week postoperatively (P < 0.007) with return to baseline levels by 6 months.

CONCLUSIONS

Sensory denervation of the ocular surface after bilateral LASIK disrupts ocular surface tear dynamics and causes irritation symptoms. Patients undergoing LASIK should be informed of these risks.

The pathology of dry eye

Homeostasis of the tear film involves delicate hormonal and neuronal regulatory mechanisms. The eye appears to be a target organ for sex hormones, particularly the androgens, as they modulate the immune system and trophic functions of the lacrimal glands and the functioning of the meibomian glands. The cornea, lacrimal glands, mucous cells, and meibomian glands are all richly innervated, indicating the importance of nervous regulation in their function. Parasympathetic, sympathetic, and sensory innervation play complex stimulatory or inhibitory roles, and neuronal pathways interact via complex surface results cascades. Abnormalities at any point in these pathways can cause overall dysregulation of lacrimal function. Whatever the initial causes of dry eye, chronic dryness of the ocular surface results in inflammatory reactions and gradual destruction of the lacrimal glands and conjunctival epithelium. Once dry eye disease has developed, inflammation is the key mechanism of ocular surface injury, as both the cause and consequence of cell damage. In practice, dry eye can be associated with Sjögren's syndrome, allergies, infection, blepharitis, and preservative-containing eye drops.

The ocular surface and tear film and their dysfunction in dry eye disease

The ocular surface, tear film, lacrimal glands, and eyelids act as a functional unit to preserve the quality of the refractive surface of the eye and to resist injury and protect the eye against changing bodily and environmental conditions. Events that disturb the homeostasis of this functional unit can result in a vicious cycle of ocular surface disease. The tear film is the most dynamic structure of the functional unit, and its production and turnover is essential to maintaining the health of the ocular surface. Classically, the tear film is reported to be composed of three layers: the mucin, aqueous, and lipid layers. The boundaries and real thickness of such layers is still under discussion. A dysfunction of any of these layers can result in dry eye disease.

Dry eye disease: the scale of the problem

Dry eye disease, or keratoconjunctivitis sicca, is among the most frequently established diagnoses in ophthalmology; in Germany, one in four patients consulting an ophthalmologist complains of the symptoms of dry eye. Although epidemiological studies investigating the prevalence of dry eye disease are rare, published studies indicate that up to 20% of adults aged 45 years or more experience dry eye symptoms. Recent studies have shown that immunologic changes play a role in the pathogenesis of dry eye, not only in Sjögren's syndrome, but also in postinfectious and age-related conditions. Despite increasing understanding of the pathogenic factors involved in dry eye disease, there has been a lack of consensus on diagnostic criteria, classification of disease states, and the aims and interpretation of specific diagnostic tests. There is a need, therefore, for standardization of disease terminology and diagnostic tests in order to improve the usefulness of epidemiological and clinical investigation of this important ocular disorder.

The treatment of dry eye

The most widely used therapy for dry eye disease is tear replacement by topical artificial tears. Punctal occlusion to prevent the drainage of natural or artificial tears is the most common non-pharmacological treatment. These and other traditional therapies for dry eye disease are only palliative, however, as they replace or conserve the tears without necessarily correcting the underlying disease process. As our understanding of the pathology of dry eye disease improves, new treatment strategies are being developed. Topical anti-inflammatory and immunomodulatory agents, such as cyclosporin A, are under investigation in the treatment of dry eye, as it is anticipated that they will correct the vicious cycle of inflammation and cell damage on the ocular surface and lacrimal glands.

Dry eye: an update on clinical diagnosis, management and promising new treatments

Dry eye conditions are prevalent with one in four to five patients presenting to eye care practitioners having dry eye signs and/or symptoms. An intimate relationship exists between the ocular surface and the tear film. The cycle of tear film instability and ocular surface damage characteristic of dry eye conditions suggests that dry eye represents a dysfunction of an integrated ocular surface-lacrimal gland unit. Therefore, dry eye is a multifactorial condition and an approach based on clinical subtypes is required for diagnosis and management. There is increasing evidence that inflammation is a contributing and exacerbating factor in dry eye conditions and anti-inflammatory or immunomodulatory therapy for chronic dry eye conditions may facilitate ocular surface healing. Other promising new treatments for dry eye include new generation artificial tear polymers and preservative systems, secretagogues, topical androgen supplements and surgical techniques for ocular surface reconstruction.

Decrease in tear secretion and corneal sensitivity after laser in situ keratomileusis

PURPOSE

To evaluate tear secretion and corneal sensitivity after laser in situ keratomileusis (LASIK) for the correction of myopia.

METHODS

In a prospective study, 48 consecutive eyes (24 patients) underwent LASIK to correct myopia ranging from -3.5 to -12.25 diopters. Tear secretion tested by the tear function index and corneal sensitivity tested using the Cochet-Bonnet esthesiometer were evaluated preoperatively and 1 week and 1, 3, 6, and 9 months postoperatively.

RESULTS

Tear secretion and corneal sensitivity after LASIK were reduced during the first 3 months after surgery (p<0.001). Tear secretion returned to its preoperative values only after 9 months. Tear secretion and corneal sensitivity were more depressed in long-term contact lens wearers preoperatively and 6 months after surgery (p<0.05).

CONCLUSION

In the correction of myopia, tear secretion was depressed after LASIK during the first 6 months after surgery.

The conjunctival epithelium in dry eye subtypes: effect of preserved and non-preserved topical treatments

PURPOSE

To determine the effect of topical treatments on the conjunctiva in dry eye.

METHODS

N = 134 dry eye subjects were diagnosed using a protocol of McMonnies dry eye symptom survey score > 14, fluorescein break up time (FBUT) < 10 s and presence of rose Bengal staining. Differential diagnosis of dry eye subtypes was based on biomicroscopic signs and ocular/medical history. Superficial perilimbal bulbar conjunctival epithelial samples were collected using impression cytology. The nucleo-cytoplasmic ratio (N/C), goblet cell density (GCD) and expression of monoclonal antibodies HLA DR and CD23 were determined. The ocular surface characteristics of untreated subjects, those receiving preserved dry eye treatments and those receiving non-preserved treatments were compared with each other and with controls. Ocular surface characteristics of dry eye subtypes were also examined.

RESULTS

An increase in N/C (p = 0.011), reduction in GCD (p = 0.0001) and increase in expression of HLA DR (p = 0.0001) and CD23 (p = 0.0001) were detected in the untreated group compared to controls. No significant differences were found between the group receiving non-preserved dry eye treatments and untreated dry eye group. The group receiving preserved treatments had a reduced GCD (p = 0.0003) and increased expression of HLA DR (p = 0.0003) and CD23 (p = 0.0001) compared to the group receiving non-preserved treatments. Dry eye subtype specific differences in HLA DR and CD23 expression were noted.

CONCLUSIONS

The conjunctival inflammation and reduced goblet cell density of dry eye is exacerbated by use of preserved topical agents, and is not significantly improved by use of non-preserved artificial tear supplements alone. Therapeutic strategies for dry eye should aim to increase goblet cell density and control ocular surface inflammation.

Immunohistochemical detection of estrogen and progesterone receptor in human cornea

OBJECTIVE

For treatment of postmenopausal keratoconjunctivitis sicca hormone therapy is favored by some clinicians. The likely morphological basis assessing the hormone receptor status in the human cornea has not been performed. Immunohistochemical staining methods provide the opportunity to evaluate the hormone receptor content within the histologic compartments of the cornea. The aim of our study was to assess and localize immunohistochemical hormone receptor staining in the human cornea.

METHODS

Formalin-fixed and paraffin-embedded specimens of three pre- and three postmenopausal women were assessed for localization of estrogen receptor (ER) and progesterone receptor (PR) expression with established immunohistochemical hormone receptor staining methods.

RESULTS

No nuclear staining reaction was found in the epi- and endothelial layers of the corneas. The stroma of the corneas showed no immunohistochemical staining reaction in all cases. We found cytoplasmatic PR staining of the endothelial layer in two cases.

CONCLUSIONS

We found no morphological basis in the human cornea for the use of topical steroid hormone treatment in postmenopausal keratoconjunctivitis sicca. Hormone receptor expression in the conjunctiva or in the lacrimal gland may have an impact in some patients showing relief of symptoms in postmenopausal dry eye syndrome.

Flow cytometric analysis of conjunctival epithelium in ocular rosacea and keratoconjunctivitis sicca

PURPOSE

To investigate by flow cytometry and impression cytology (IC) specimens the inflammatory status of the conjunctival epithelium and goblet cell density in two series of patients with rosacea and dry eye syndrome compared with a population of healthy subjects.

DESIGN

Nonrandomized, prospective, comparative case series.

PARTICIPANTS

Twenty-six eyes of 13 patients with rosacea, 26 eyes of 13 patients with dry eye syndrome, and 24 eyes of 12 control subjects were included in this study.

METHODS

IC specimens were collected after clinical examination of the ocular surface and analyzed by flow cytometry, using antibodies directed to human lymphocyte antigen-DR (HLA-DR), intercellular adhesion molecule-1 (ICAM-1) (CD 54), and the peptidic core of the conjunctival mucin (M1/MUC5AC). The percentage of positive cells was calculated and levels of fluorescence expression quantified and compared with those obtained in a series of 12 healthy subjects.

MAIN OUTCOME MEASURES

Tear break-up time (TBUT), Schirmer test, fluorescein and lissamin green stainings, and IC were realized in this study.

RESULTS

A significant increase of HLA-DR and ICAM-1 expressions by epithelial cells was consistently found in the two pathologic groups compared with levels calculated in normal eyes. The two markers were well correlated with each other and inversely with TBUT and Schirmer test. The percentage of goblet cells was significantly decreased in rosacea patients and in dry eye patients compared with the normal group with a significant negative correlation with both HLA DR and ICAM-1 markers.

CONCLUSIONS

Ocular rosacea and keratoconjunctivitis sicca were associated with severe ocular surface changes, such as an overexpression of inflammatory markers and a significant decrease in the number of goblet cells.

The diagnosis and management of dry eye: a twenty-five-year review

PURPOSE

To review the advances in the diagnosis, pathogenesis, and management of dry eye disease in the past 25 years.

METHODS

Literature review.

RESULTS

The preocular tear film is a hydrated mucus gel that contains soluble antimicrobial proteins and growth factors that protect and support the ocular surface. The final common pathway in dry eye is a perturbation of the integrated ocular surface/lacrimal gland reflex unit. Diagnostic tests evaluating tear composition and clearance appear to show stronger correlation with the severity of ocular irritation symptoms and keratoconjunctivitis sicca (KCS) than the conventional Schirmer tests. KCS is a condition of abnormal differentiation and mucus production by the ocular surface epithelium that results in a poorly lubricated, abnormally permeable ocular surface that has increased susceptibility to environmental insults. Chronic subclinical ocular surface inflammation appears to play a key role in the pathogenesis of KCS. New therapeutic strategies are aimed at reducing the ocular surface inflammation of dry eye disease.

CONCLUSIONS

There has been a tremendous increase in knowledge regarding dry eye disease in the past 25 years that has resulted in improved diagnostic classification and new targeted therapies.

Interleukin-6 levels in the conjunctival epithelium of patients with dry eye disease treated with cyclosporine ophthalmic emulsion

PURPOSE

To evaluate interleukin-6 (IL-6) levels in the conjunctival epithelium of patients with moderate to severe dry eye disease before and after treatment with cyclosporin A ophthalmic emulsion (CsA) or its vehicle.

METHODS

Conjunctival cytology specimens were obtained from a subset of patients enrolled in a 6-month randomized, double-masked clinical trial of the efficacy and safety of topical CsA at baseline and after 3 and 6 months of B.I.D. treatment with 0.05% cyclosporine emulsion (n = 13), 0.1% cyclosporine emulsion (n = 8), or vehicle (n = 10). RNA was extracted and a competitive reverse transcriptase polymerase chain reaction (RT-PCR) was used to evaluate the levels of mRNA encoding the inflammatory cytokine IL-6 and a housekeeping gene, G3PDH. Levels of IL-6 and G3PDH were measured and compared.

RESULTS

There was no change from baseline in the level of G3PDH after 3 or 6 months in any group. IL-6 normalized for G3PDH (IL-6/G3PDH ratio) was not different from baseline at 3 months but showed a significant decrease from baseline in the group treated with 0.05% CsA (p = 0.048) at 6 months. No significant between-group differences were noted and no correlation was observed between the change in IL-6/G3PDH and corneal fluorescein staining.

CONCLUSIONS

This preliminary, small-cohort study showed a decrease in IL-6 in the conjunctival epithelium of moderate to severe dry eye patients treated with 0.05% CsA for 6 months. The observed decrease suggests that dry eye disease involves immune-mediated inflammatory processes that may be decreased by treatment with topical ophthalmic cyclosporine.

Frequency of dry eye diagnostic test procedures used in various modes of ophthalmic practice

PURPOSE

There are many suggested dry eye diagnostic test batteries in the literature. However, clinicians use a wide variety of dry eye diagnostic tests in clinical practice due to a number of factors, including time constraints. In addition, there has been no systematic description of the standard of care in diagnosing dry eye in the literature. The purpose of this study is to determine the type and frequency of dry eye diagnostic tests used in various modes of ophthalmic practice across a spectrum of dry eye severity.

METHODS

A total of 467 patient charts (patients with a previous dry eye diagnosis) were reviewed retrospectively to determine diagnostic test frequency. In reviewing patient charts, the following tests were identified as performed or not performed: symptom assessment, fluorescein staining, tear break-up time (TBUT), Schirmer test, rose bengal staining, and "tear assessment" (including quantity and quality of the tear meniscus).

RESULTS

Dry eye diagnostic tests were used in the following frequencies across all modes of practice: symptom assessment (82.8%), fluorescein staining (55.5%), TBUT (40.7%), tear assessment (22.2%), Schirmer test (8.5%), and rose bengal staining (4.9%). When the clinics are pooled, two test procedures were used with the highest frequency (38.9%). The most commonly performed two-test procedure combination was a symptom assessment combined with fluorescein staining of the cornea (43.7%).

CONCLUSIONS

Symptom assessment plays a large role in the diagnosis of dry eye. The current clinical standard of care for dry eye diagnosis includes the performance of at least one test procedure in addition to a symptom assessment.

Two multicenter, randomized studies of the efficacy and safety of cyclosporine ophthalmic emulsion in moderate to severe dry eye disease. CsA Phase 3 Study Group

OBJECTIVE

To compare the efficacy and safety of cyclosporin A ([CsA] 0.05% and 0.1% ophthalmic emulsions) to vehicle in patients with moderate to severe dry eye disease.

DESIGN

Multicenter, randomized, double-masked, parallel-group, 6-month, vehicle-controlled.

PARTICIPANTS

A total of 877 patients with defined moderate to severe dry eye disease (292 to 293 in each treatment group).

METHODS

Two identical clinical trials; patients were treated twice daily with either CsA, 0.05% or 0.1%, or vehicle. The results of these two trials were combined for analysis.

MAIN OUTCOME MEASURES

EFFICACY

corneal and interpalpebral dye staining, Schirmer tear test (with and without anesthesia), tear break-up time, Ocular Surface Disease Index (OSDI), facial expression, patient subjective rating scale, symptoms of dry eye, investigator's evaluation of global response to treatment, treatment success, and daily use of artificial tears.

SAFETY

occurrence of adverse events, best-corrected visual acuity, intraocular pressure, biomicroscopy, and blood trough CsA concentrations.

RESULTS

Treatment with CsA, 0.05% or 0.1%, gave significantly (P < or = 0.05) greater improvements than vehicle in two objective signs of dry eye disease (corneal staining and categorized Schirmer values). CsA 0.05% treatment also gave significantly greater improvements (P < 0.05) in three subjective measures of dry eye disease (blurred vision, need for concomitant artificial tears, and the physician's evaluation of global response to treatment). There was no dose-response effect. Both CsA treatments exhibited an excellent safety profile, and there were no significant topical or systemic adverse safety findings.

CONCLUSIONS

The novel ophthalmic formulations CsA 0.05% and 0.1% were safe and effective in the treatment of moderate to severe dry eye disease yielding improvements in both objective and subjective measures. Topical CsA represents a new pharmacologically based treatment for dry eye disease that may provide significant patient benefits.

A new look at dry eye disease and its treatment

This review examines the impact of moderate to severe dry eye disease on daily life and medical-resource utilization. The results suggest that current treatment paradigms can lead to unacceptable costs in both quality of life and progressive use of healthcare resources. Evidence linking this disease to T-cell-mediated inflammatory processes lays the foundation for understanding the clinical benefits of topical cyclosporine, an immunomodulatory and anti-inflammatory agent.