Current opinion of immunotherapy for ocular allergy

ICON: Diagnosis and management of allergic conjunctivitis

Ocular allergy (OA), interchangeably known as allergic conjunctivitis, is a common immunological hypersensitivity disorder affecting up to 40% of the population. Ocular allergy has been increasing in frequency, with symptoms of itching, redness, and swelling that significantly impacts an individual's quality of life (QOL). Ocular allergy is an often underdiagnosed and undertreated health problem, because only 10% of patients with OA symptoms seek medical attention, whereas most patients manage with over-the-counter medications and complementary nonpharmacological remedies. The clinical course, duration, severity, and co-morbidities are varied and depend, in part, on the specific ocular tissues that are affected and on immunologic mechanism(s) involved, both local and systemic. It is frequently associated with allergic rhinitis (commonly recognized as allergic rhino conjunctivitis), and with other allergic comorbidities. The predominance of self-management increases the risk of suboptimal therapy that leads to recurrent exacerbations and the potential for development of more chronic conditions that can lead to corneal complications and interference with the visual axis. Multiple, often co-existing causes are seen, and a broad differential diagnosis for OA, increasing the difficulty of arriving at the correct diagnosis(es). Ocular allergy commonly overlaps with other anterior ocular disease disorders, including infectious disorders and dry eye syndromes. Therefore, successful management includes overcoming the challenges of underdiagnosis and even misdiagnosis by a better understanding of the subtleties of an in-depth patient history, ophthalmologic examination techniques, and diagnostic procedures, which are of paramount importance in making an accurate diagnosis of OA. Appropriate cross-referral between specialists (allergists and eyecare specialists) would maximize patient care and outcomes. This would significantly improve OA management and overcome the unmet needs in global health.

Clinical implications of mast cell involvement in allergic conjunctivitis

The conjunctiva is a common site for the allergic inflammatory response due to it being highly vascularized, having constant exposure to environmental pollutants and allergenic pollens and having a unique conjunctival associated lymphoid tissue. The primary morbidity of anterior surface conjunctival disorders that include allergic conjunctivitis and tear film disorders is associated with its high frequency of involvement rather than its severity, although the more chronic forms can involve the cornea and lead to sight-threatening conditions. Ocular allergy is associated with IgE-mediated mast cell activation in conjunctival tissue leading to the release of preformed mediators including histamine and proteases and subsequent de novo formation of lipid-derived mediators and cytokines that trigger a cascade of cellular and molecular events leading to extensive migration and infiltration of inflammatory cells to the ocular surface. The trafficking of neutrophils, eosinophils, and lymphocytes to the ocular surface is due to establishing various chemokine gradients (mainly CCL11, CCL24, CCL5, MCP-3, and MCP-4), cell surface expression of adhesion molecules (such as VCAM-1 the ligand for VLA-4), and leukocyte adhesion to vascular endothelium. The release of preformed mediators underlies the acute ocular surface response while the secondary influx of inflammatory cells leading to the recruitment and activation of eosinophils and the subsequent activation of Th2 and Th1 lymphocytes at the level of the conjunctiva reflects the late-phase reaction.

Component-resolved diagnostics in vernal conjunctivitis

BACKGROUND

Conventional diagnostic tests in allergy are insufficient to clarify the origin of vernal conjunctivitis (VC).

OBJECTIVES

To evaluate IgE-mediated hypersensitivity by component-resolved diagnosis (CRD) in tears and serum from patients with VC and to evaluate how to treat patients with identified triggering allergens by specific immunotherapy.

METHODS

Patients were divided into 3 groups: (1) patients with VC (25 patients), (2) patients allergic to grass pollen with seasonal allergic conjunctivitis (AC) (50 patients), and (3) healthy blood donors (50 patients). If triggering allergens were detected, specific conventional immunotherapy was administered for 1 year.

RESULTS

Twenty-five patients with VC were evaluated. The identified triggering allergens were n Lol p 1 (11 patients), n Cyn d 1 (8 patients), group 4 and 6 grasses (6 patients), and group 5 grasses (5 patients). Prick test and pollen IgE test results were positive in one patient. Clinical improvement was observed in 13 of the 25 patients with VC after 1 year of specific immunotherapy.

CONCLUSION

CRD seems to be a more sensitive diagnostic tool compared with prick test and IgE detection. Specific CRD-led immunotherapy may achieve clinical improvements in patients with VC.

Management of seasonal allergic conjunctivitis: guide to therapy

Seasonal allergic conjunctivitis (SAC) is an inflammatory response of the conjunctiva triggered by exposure to seasonal allergens. Treatment options for SAC include artificial tears, antihistamines, decongestants, mast cell stabilizers, nonsteroidal anti-inflammatory drugs, dual antihistamine/mast cell stabilizers, immunotherapy and corticosteroids. Topical, intranasal and systemic formulations of corticosteroids have traditionally provided the most effective relief of the inflammation and signs and symptoms associated with severe, acute exacerbations of SAC. However, steroid-induced ocular and systemic side-effects have limited the prescribing of these agents. This limitation of traditional corticosteroids led to the development of modified corticosteroids that retain the anti-inflammatory mechanism of action of traditional corticosteroids with a much-improved safety profile because of their rapid breakdown to inactive metabolites after exerting their activity. The development of one such novel corticosteroid, loteprednol etabonate (LE), led to the insertion of an ester (instead of a ketone) group at the carbon-20 (C-20) position of the basic corticosteroid structure. Clinical trials assessing this C-20 ester corticosteroid have demonstrated similar efficacy to C-20 ketone corticosteroids in the prevention or treatment of the signs and symptoms of SAC but with a greatly improved safety profile, as the C-20 ester corticosteroid is less likely to elevate intraocular pressure. In addition, the ketone at the C-20 position has been implicated in the formation of cataract, while nonketolic corticosteroids do not form Schiff base intermediates with lens proteins, which is a common first step in cataractogenesis. The clinical relevance of the C-20 ester corticosteroid class, as modelled by LE, is that they provide both effective and safe treatment of the inflammation associated with SAC and relief of its signs and symptoms. Loteprednol etabonate offers a well-tolerated treatment option for patients with debilitating acute exacerbations as well as chronic forms of the disease.

A review of non-pharmacological and pharmacological management of seasonal and perennial allergic conjunctivitis

Allergic eye disease encompasses a group of hypersensitivity disorders which primarily affect the conjunctiva and its prevalence is increasing. It is estimated to affect 8% of patients attending optometric practice but is poorly managed and rarely involves ophthalmic assessment. Seasonal allergic conjunctivitis (SAC) is the most common form of allergic eye disease (90%), followed by perennial allergic conjunctivitis (PAC; 5%). Both are type 1 IgE mediated hypersensitivity reactions where mast cells play an important role in pathophysiology. The signs and symptoms are similar but SAC occurs periodically whereas PAC occurs year round. Despite being a relatively mild condition, the effects on the quality of life can be profound and therefore they demand attention. Primary management of SAC and PAC involves avoidance strategies depending on the responsible allergen(s) to prevent the hypersensitivity reaction. Cooled tear supplements and cold compresses may help bring relief. Pharmacological agents may become necessary as it is not possible to completely avoid the allergen(s). There are a wide range of anti-allergic medications available, such as mast cell stabilisers, antihistamines and dual-action agents. Severe cases refractory to conventional treatment require anti-inflammatories, immunomodulators or immunotherapy. Additional qualifications are required to gain access to these medications, but entry-level optometrists must offer advice and supportive therapy. Based on current evidence, the efficacy of anti-allergic medications appears equivocal so prescribing should relate to patient preference, dosing and cost. More studies with standardised methodologies are necessary elicit the most effective anti-allergic medications but those with dual-actions are likely to be first line agents.

Sublingual immunotherapy for treating allergic conjunctivitis

BACKGROUND

Allergic ocular symptoms, although frequently trivialised, are common and represent an important comorbidity of allergic rhinitis. Sublingual Immunotherapy (SLIT) is an effective and well-tolerated treatment for allergic rhinitis, but its effects on symptoms of ocular allergy have not been well established.

OBJECTIVES

To evaluate the efficacy of SLIT compared with placebo for reductions in ocular symptoms, topical ocular medication requirements and conjunctival immediate allergen sensitivity.

SEARCH STRATEGY

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 1), MEDLINE (January 1950 to January 2011), EMBASE (January 1980 to January 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2011), Web of Science (January 1970 to January 2011), Biosis Previews, (January 1979 to January 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (January 2011), ClinicalTrials.gov (www.clinicaltrials.gov) (January 2011), the Australian New Zealand Clinical Trials Registry (ANZCTR) (www.actr.org.au) (July 2010), SCOPUS (November 2008) and the UK Clinical Trials Gateway (January 2010). There were no language or date restrictions in the search for trials. All electronic databases except for SCOPUS, the UK Clinical Trials Gateway and ANZCTR were last searched on 19 January 2011.

SELECTION CRITERIA

Randomised controlled trials (RCTs), double-masked and placebo controlled, which evaluated the efficacy of SLIT in patients with symptoms of allergic rhinoconjunctivitis (ARC) or allergic conjunctivitis (AC).

DATA COLLECTION AND ANALYSIS

The primary outcome was the total ocular symptom scores. Secondary endpoints included individual ocular symptom scores (such as itchy eyes, red eyes, watery eyes, swollen eyes), ocular medication scores (eye drops) and conjunctival immediate allergen sensitivity (CIAS). Data were analysed and reported as standardised mean differences (SMDs) using Review Manager software.

MAIN RESULTS

Forty-two trials (n = 3958 total participants; n= 2011 SLIT and n = 1947 placebo) had available data to evaluate the efficacy of SLIT on AC and were included in the meta-analyses. Heterogeneity among studies (I(2) statistic) was around 50% or below for all endpoints. Sublingual immunotherapy induced a significant reduction in both total ocular symptom scores (SMD -0.41; 95% confidence interval (CI) -0.53 to -0.28; P < 0.00001; I(2) = 59%) and individual ocular symptom scores for red eyes (SMD -0.33; 95% CI -0.45 to -0.22; P < 0.00001; I(2) = 27%), itchy eyes (SMD -0.31; 95% CI -0.42 to -0.20; P < 0.00001; I(2) = 46%) and watery eyes (SMD -0.23; 95% CI -0.34 to -0.11; P < 0.0001; I(2) = 42%) compared to placebo. Those participants having active treatment showed an increase in the threshold dose for the conjunctival allergen provocation test (SMD 0.35; 95% CI 0.00 to 0.69; P = 0.05; I(2) = 43%). No significant reduction was observed in ocular eye drops use (SMD -0.10; 95% CI -0.22 to 0.03; P = 0.13; I(2) = 34%).

AUTHORS' CONCLUSIONS

Overall, SLIT is moderately effective in reducing total and individual ocular symptom scores in participants with ARC and AC. There were however some concerns about the overall quality of the evidence-base, this relating to inadequate descriptions of allocation concealment in some studies, statistical heterogeneity and the possibility of publication bias. There is a need for further large rigorously designed studies that study long-term effectiveness after discontinuation of treatment and establish the cost-effectiveness of SLIT.

Allergic conjunctivitis and nasal allergy

Allergic conjunctivitis (AC) can be divided into the primary form (caused by an allergic reaction occurring primarily in the conjunctivae) and the secondary form (induced by allergic reaction originating primarily in the nasal mucosa, where the released mediators can reach conjunctiva through the lacrimal system, the blood, the lymphatic network, or the neurogenic network). Patients with primary AC develop an immediate, late, or delayed conjunctival response (CR) during conjunctival provocation tests. Patients with secondary AC develop an immediate, late, or delayed type of secondary CR, induced by the nasal allergic reaction, due to the nasal allergen challenge. Various hypersensitivity mechanisms may be involved in the particular CR types. The secondarily induced AC and CRs can only be confirmed by nasal provocations tests, performed by rhinomanometry combined with recording of conjunctival signs. The existence of the primary and secondarily induced AC has an impact on treatment of this disorder.

Emerging drugs for conjunctivitis

BACKGROUND

Conjunctivitis is a highly prevalent ocular condition with potential complications that include visual impairment. Infectious causes include bacterial, viral, parasitic and fungal etiologies, while noninfectious conjunctivitis is typically owing to allergy, tear film dysfunction or chemical trauma. Treatment requires frequent dosing and often lacks complete efficacy.

OBJECTIVE

The goal of this review is to investigate therapies for conjunctivitis that are undergoing clinical study and development. These data are presented in light of currently available treatment options to provide an understanding of the present and future direction of conjunctivitis management.

METHODS

The Pharmaprojects database was searched for conjunctivitis therapies currently in development around the world. Current treatment guidelines for infectious and noninfectious conjunctivitis were researched through PUBMED and OVID databases.

RESULTS

Several new compounds, including antimicrobial, antihistamine, anti-inflammatory and immunomodulating drugs, along with a novel thiazolidinedione, are currently undergoing investigation for their potential use in conjunctivitis management. These ophthalmic agents show promise in improving clinical outcomes for infectious and noninfectious conjunctivitis.

Allergic conjunctivitis

Allergic conjunctivitis is common, especially during the allergy season. Consultation with the allergist to perform skin tests or in vitro tests may be useful and confirmatory in the diagnosis of ocular allergy. If treatment is necessary, antihistamines, mast cell stabilizers, and nonsteroidal anti-inflammatory drugs are safe and reasonably effective. Corticosteroids are an order of magnitude more potent than noncorticosteroids; however, they have attendant side effects that are best monitored by the ophthalmologist. The development of "modified" corticosteroids has been a boon to the treatment of ocular allergy because these drugs may reduce potential side effects without sacrificing potency.

Differential diagnoses of conjunctivitis for clinical allergist-immunologists

OBJECTIVE

To provide a clinical overview of the types of conjunctivitis that are encountered by practicing clinical allergist-immunologists.

DATA SOURCES

Published literature in peer reviewed journals found in the National Library of Medicine (PubMed) database using the keywords ocular allergy and/or allergic conjunctivitis.

STUDY SELECTION

Studies related to ocular allergy and/or allergic conjunctivitis were selected for inclusion in this review.

RESULTS

Four clinical scenarios are presented that mimic frequently encountered inflammatory disorders that present as red eyes.

CONCLUSIONS

The signs and symptoms associated with the various inflammatory conditions affecting the conjunctiva often overlap and need to be differentiated to maximize care for patients with conjunctivitis.

Allergic diseases of the eye

The prevalence of ocular allergy is clearly underappreciated; it has been an underdiagnosed and undertreated area in primary care medicine. The ocular symptoms associated with the most common ocular allergy conditions,such as seasonal and perennial AC, are twice as likely to affect the allergy sufferer as nasal symptoms alone. The emergence of new medications for the specific treatment of ocular symptoms over the course of the past 15 years offers a new field for improved patient care by the primary and sub-specialty health care providers.

Ultrastructural anatomy of CALT follicles in the rabbit reveals characteristics of M-cells, germinal centres and high endothelial venules

Conjunctiva-associated lymphoid tissue (CALT) is a part of the eye-associated lymphoid tissue (EALT) at the ocular surface. Its lymphoid follicles are usually characterized by using light microscopy, but its ultrastructure remains largely unknown. In this study, flat whole-mount conjunctival tissues (n = 42) from 21 young adult rabbits were investigated native in reflected light, and further stained and cleared (n = 6), in paraffin histology sections (n = 6), scanning electron microscopy (SEM, n = 4) and transmission electron microscopy (TEM, n = 4). Secondary lymphoid follicles accumulated into a dense group nasally towards the lacrimal punctum of the lower lid. High endothelial venules (HEV) with typical ultrastructure occurred in the parafollicular zone. The bright germinal centre (GC) contained lymphoblasts, follicular dendritic cells, apoptotic cells and tingible body macrophages. The follicle-associated epithelium (FAE) was devoid of goblet cells and contained groups of lymphoid cells. TEM showed these cells to be located in cytoplasmic pockets of superficial electron-lucent cells with a thin cytoplasmic luminal lining that contained a fine filament meshwork and numerous endocytotic vesicles. These M-cells were sitting between and on top of the ordinary dense epithelial cells that were located basally and formed pillar-like structures. In stereoscopic SEM, the surface cells were very large, had a polygonal outline and covered cavernous spaces. The rabbit has a CALT with typical follicular morphology, including HEV for regulated lymphocyte migration and epithelial cells with ultrastructural characteristics of M-cells that allow antigen transport as indicated by the GC-reaction. The arrangement of these M-cells on top of and between epithelial pillar cells may reflect a special structural requirement of the multilayered CALT FAE.

Review of complementary and alternative medicine in treatment of ocular allergies

PURPOSE OF REVIEW

Ocular allergy is a common complaint of allergy sufferers, many of whom may choose to use complementary and alternative medicine in the treatment of these symptoms. In this review major complementary and alternative medicine modalities including herbal therapies, acupuncture, homeopathy, alternative immunotherapy and behavior modification are assessed for evidence of their effectiveness in the treatment of ocular allergy symptoms.

RECENT FINDINGS

Certain herbs including Euphrasia officinalis, Petasites hybridus and Argemone mexicana have been evaluated in control studies in the treatment of ocular allergy. Honey is no more effective than placebo in the treatment of ocular allergy. Acupuncture used regularly has demonstrated some positive trends in ocular allergy sufferers. Homeopathy has shown conflicting results in the treatment of ocular allergy, while alternative forms of immunotherapy have been shown to develop immunologic tolerogenic effects in the control of the condition.

SUMMARY

Several forms of complementary and alternative medicine have been studied for their effectiveness in treatment of ocular allergy symptoms. Further research is needed to assess mechanisms of action and to establish practice guidelines for the use of these modalities