Allergic conjunctivitis: symptoms and treatment options

Allergic conjunctivitis is an inflammatory reaction of the conjunctiva to allergens, most commonly pollen, mite, epidermal, and household allergens. The key symptom is itching, usually bilateral, accompanied by redness, lacrimation, and a burning sensation. This condition falls within the spectrum of ocular allergies and often accompanies allergic rhinitis, forming a unified clinical picture of rhinoconjunctivitis. [1]

Most cases are seasonal or perennial and benign, but severe variants, such as vernal and atopic keratoconjunctivitis, can lead to corneal damage and vision loss. Early stratification of severity and the selection of step-by-step therapy allow for rapid relief of itching and the prevention of complications. [2]

The modern approach is based on a combination of non-drug measures, topical antihistamines with membrane-stabilizing properties, control of concomitant allergic rhinitis, and the use of short courses of topical corticosteroids during severe exacerbations. In recurrent cases, allergen-specific immunotherapy is considered the only method that modifies the natural course of allergic disease. [3]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, allergic conjunctivitis is coded in block H10 "Conjunctivitis." For acute atopic variants, codes H10.1 are used, taking into account lateralization; for chronic allergic forms, codes H10.45 are used. If data are insufficient, H10.9 "Conjunctivitis, unspecified" is permitted; however, it is preferable to indicate the specific type. [4]

In the International Classification of Diseases, Eleventh Revision, allergic conjunctivitis is classified under code 9A60.02 in the "Conjunctivitis" group. Severe variants, such as vernal keratoconjunctivitis and atopic keratoconjunctivitis, are listed separately, which helps with more accurate risk stratification and treatment planning. [5]

Table 1. Codes for allergic conjunctivitis

System	Code	Name
ICD-10	H10.1	Acute atopic conjunctivitis
ICD-10	H10.45	Other chronic allergic conjunctivitis
ICD-10	H10.413	Chronic giant papillary conjunctivitis, bilateral
ICD-11	9A60.02	Allergic conjunctivitis
ICD-11	9A60.5	Vernal keratoconjunctivitis
ICD-11	4A81	Allergic and hypersensitivity diseases involving the eye
Source of codes - manuals and reference books on ICD-10 and ICD-11. [6]

Epidemiology

Allergic conjunctivitis is extremely common and accounts for a significant proportion of all ophthalmological visits in outpatient practice. According to a systematic review, seasonal and year-round forms occur in approximately 15-20% of the population, and ocular symptoms are reported by a significant proportion of patients with allergic respiratory diseases. These ranges vary depending on region, age, and allergen exposure. [7]

Epidemiological studies in large populations have shown an increase in the prevalence of ocular allergies in recent decades, which is associated with environmental changes and urbanization. The peak age is in young and middle-aged adults, but symptoms often persist throughout life with fluctuating intensity. [8]

The severity of seasonality is determined by local pollen calendars, climate, and the spectrum of sensitization. The contribution of household allergens, such as house dust mites and epidermal allergen components, supports year-round forms and determines the tailed part of the distribution of severe cases. [9]

Seasonal forms account for the majority of ocular allergies, while severe forms remain relatively rare. However, they contribute disproportionately to quality-of-life deterioration and corneal risks. This necessitates early identification and treatment of such patients. [10]

Table 2. Epidemiological landmarks

Indicator	Range
The proportion of seasonal and year-round forms in the population	15-20%
Corresponds to allergic rhinitis	Very common
Peak age	Teens and young adults
Severe forms	Much less frequently, high burden on quality of life
Summary data - from reviews and practical guidelines. [11]

Reasons

Trigger allergens are most often tree, grass, and weed pollen, house dust mites, animal epidermal allergens, and mold spores. Contact with an allergen on the conjunctival surface triggers a cascade of mediator release, rapidly leading to itching and hyperemia. Nasal symptoms are often present, suggesting a common atopic basis. [12]

There are contact forms caused by cosmetics, eye drops, and preservatives, as well as reactions to contact lenses and deposits on their surface. These variants are often classified as drug-induced and giant papillary conjunctivitis, requiring elimination of the trigger and modification of eye care. [13]

In a significant proportion of patients, sensitization is systemic, involving the nasal and bronchial mucosa. This explains the effectiveness of strategies aimed at controlling allergic rhinitis and modifying the allergic response using immunotherapy. [14]

Environmental factors include air pollution, microparticles, and climate conditions that increase exposure to allergens and microtrauma to the ocular surface from wind and dust. These factors increase the likelihood of exacerbations and persistent symptoms during the off-season. [15]

Risk factors

A hereditary predisposition to atopy, the presence of allergic rhinitis, bronchial asthma, and atopic dermatitis significantly increase the likelihood of developing ocular allergies. Family and individual history data help predict the seasonality and severity of symptoms. [16]

Constant exposure to household allergens, pet ownership, dust accumulation, and high indoor humidity contribute to year-round conjunctival inflammation. Environmental modifications often lead to clinically significant symptom reduction. [17]

Wearing contact lenses, especially with poor hygiene and prolonged use, is associated with the risk of giant papillary conjunctivitis due to chronic mechanical stimulation and deposits on the lens surface. Changing the lens material, regimen, and care products reduces the risk of recurrence. [18]

Medications and preservatives in eye drops can cause drug-induced conjunctivitis. Assessing the medication history, list of topical medications, and using preservative-free forms reduces the likelihood of this scenario. [19]

Table 3. Main risk factors

Factor	Comment
Atopic history	Genetic and immune predisposition
Allergic rhinitis	Commonalities of Sensitization and Inflammation
Contact lenses	Mechanical irritation and deposits
Local preparations and preservatives	Risk of drug-induced inflammation
Air pollution	Increased symptoms and frequency of exacerbations
Rationale - clinical reviews and positions of professional societies. [20]

Pathogenesis

The disease is characterized by an immediate-type reaction mediated by immunoglobulin E, with degranulation of conjunctival mast cells and the release of histamine. This causes itching, vasodilation of superficial vessels, and increased lacrimation within minutes of contact with the allergen. [21]

Following the early phase, a late phase of inflammation develops involving eosinophils, T-helper cells type 2, and cytokines such as interleukins types 4 and 5. This cascade maintains the persistence of symptoms, increases receptor sensitivity, and determines the effectiveness of membrane-stabilizing therapy. [22]

In severe cases, epithelial damage and tissue remodeling lead to the formation of large papillae, filiform discharge, and corneal involvement. Anti-inflammatory immunosuppressive therapy is essential to prevent erosions and opacities. [23]

Cross-allergic reactions and concomitant allergic rhinitis explain the effect of treatments directed at the nasal mucosa and systemic modification of the allergic response, including allergen-specific immunotherapy.[24]

Symptoms

The leading symptom is itching, usually bilateral and severe, aggravated by scratching the eyelids. The picture is complemented by lacrimation, redness, a gritty sensation in the eyes, and often photophobia with more severe inflammation. Symptoms are often accompanied by sneezing and nasal discharge. [25]

Examination reveals conjunctival injection, conjunctival and eyelid edema, watery or mucous discharge, and papillary changes on the tarsal conjunctiva. The absence of severe pain and corneal clouding distinguishes the uncomplicated form from keratitis. [26]

Seasonal exacerbations correlate with pollen periods, while year-round forms produce less severe but persistent symptoms with episodes of exacerbation upon contact with household allergens. Interrupting exposure often brings rapid relief. [27]

Contact lens wearers also report discomfort, stickiness, and thread-like discharge; examination reveals large papillae on the upper eyelid, suggesting a giant papillary variant. [28]

Table 4. Complaints and symptoms of allergic conjunctivitis

Category	The most common
Complaints	Itching, tearing, redness, burning
Signs	Conjunctival injection, swelling, mucous discharge
Associations	Allergic rhinitis, sneezing, congestion
Warning signs	Pain, decreased visual acuity, severe photophobia
Summary - according to clinical guidelines. [29]

Classification, forms and stages

Seasonal allergic conjunctivitis and perennial allergic conjunctivitis are the most common forms, differing in triggers and symptom pattern. Both types have a predominantly benign course with proper management. [30]

Contact forms include drug-induced and allergic contact blepharoconjunctivitis, where the main treatment is the elimination of the provoking factor and the transition to preservative-free drugs. [31]

Giant papillary conjunctivitis develops in the presence of contact lenses, prostheses, or sutures and requires changes in care, material selection, and wearing regimen. If necessary, anti-inflammatory drops are used to relieve symptoms. [32]

Severe allergic eye diseases include vernal and atopic keratoconjunctivitis, which require joint management by an ophthalmologist and an allergist and the use of steroid-sparing regimens. [33]

Table 5. Classification of allergic conjunctivitis

Group	Examples
Frequent forms	Seasonal uniform, year-round uniform
Contact forms	Drug-induced variant, contact blepharoconjunctivitis
Mechanically associated	Giant papillary conjunctivitis
Severe forms	Vernal keratoconjunctivitis, atopic keratoconjunctivitis
Rationale - Ocular allergy reviews and practice guides.[34]

Complications and consequences

In uncomplicated cases, the main negative effect is associated with sleep and work impairment due to itching and watery eyes. Chronic discomfort leads to a decrease in quality of life, especially during high pollen seasons. [35]

In severe cases, corneal damage with erosions, punctate keratitis, formation of thyroid defects, and scarring is possible, leading to a risk of decreased visual acuity. These cases require aggressive inflammation control. [36]

Prolonged and uncontrolled use of vasoconstrictor drops can cause tachyphylaxis and late hyperemia, worsening symptoms and masking inflammation. Guidelines recommend avoiding long-term use of such agents. [37]

Drug-induced inflammation and toxic reactions to preservatives represent a distinct problem requiring a review of therapy and a switch to preservative-free preparations. The risk increases with multicomponent topical therapy. [38]

Table 6. Potential complications

Complication	Clinical significance
Decreased quality of life	Sleep and productivity disturbances
Corneal damage	Risk of decreased visual acuity in severe forms
Late hyperemia with vasoconstrictor drops	Increased complaints, masking of inflammation
Drug-induced reactions	The need to change therapy and forms
Summary - based on current reviews and guidelines. [39]

When to see a doctor

An urgent ophthalmologist consultation is indicated in cases of severe pain, noticeable decrease in visual acuity, severe photophobia, unilateral inflammation, eye trauma, or exposure to chemicals. These symptoms are not typical of uncomplicated allergies and may indicate keratitis or another serious condition. [40]

For patients with prolonged relapses, insufficient effect from over-the-counter medications and the need for frequent use of vasoconstrictor drops, a scheduled visit is recommended to select anti-inflammatory therapy and exclude drug-induced reactions. [41]

Contact lens wearers who experience thread-like discharge, discomfort, or decreased tolerance should temporarily discontinue wearing their lenses, evaluate their lens care and material, and undergo an examination with eversion of the upper eyelid. [42]

If allergic rhinitis symptoms are combined, a consultation with an allergist is advisable to select nasal treatment and consider allergen-specific immunotherapy. This improves control of ocular symptoms and reduces the need for drops. [43]

Diagnostics

Step 1. Collect anamnesis, specifying seasonality, contact with allergens, rhinitis symptoms, wearing contact lenses, use of eye drops and cosmetics. Assess the dynamics of symptoms against the background of elimination of exposure. [44]

Step 2. Biomicroscopy with assessment of the degree of hyperemia, edema, nature of discharge, papillary changes in the tarsal conjunctiva, and the condition of the cornea. Eversion of the upper eyelid is mandatory if the giant papillary variant is suspected. [45]

Step 3. Exclude infectious causes based on clinical and epidemiological history. If adenoviral infection is suspected, watery discharge, follicular reaction, and high contagiousness are considered. [46]

Step 4. Confirm the atopic profile if necessary: skin tests or specific immunoglobulin E as indicated for immunotherapy planning. Ointments and tests for preservatives and cosmetics are used in cases of contact reactions. [47]

Table 7. Diagnostic benchmarks and tests

Stage	Target
History and exposure	Identify triggers and seasonality
Slit lamp examination	Assess the signs and rule out keratitis
Exclusion of infection	Distinguish between viral and bacterial forms
Allergy testing	Planning immunotherapy if needed
Summary - based on guidelines and reviews. [48]

Differential diagnosis

Viral conjunctivitis is characterized by high contagiousness, follicles, preauricular lymphadenopathy, and often unilateral onset, whereas allergic conjunctivitis is characterized by itching and bilaterality. The absence of thick pus and systemic prodromal symptoms helps differentiate these conditions. [49]

Bacterial conjunctivitis often causes thick, purulent discharge, eyelid sticking in the morning, and less severe itching. A rapid response to antibacterial drops confirms an infectious nature. [50]

Dry eye syndrome and blepharitis can mimic redness and burning, but allergies are characterized by sudden flare-ups, a connection to allergens, and a leading itch. Assessing the eyelid margin and tear film stability helps rule out these conditions. [51]

Drug-induced conjunctivitis and toxic reactions to preservatives are characterized by persistent hyperemia and burning sensation despite the use of multiple drops. Discontinuation of the suspected medication and switching to preservative-free forms is a key diagnostic step. [52]

Table 8. Differential features

State	Distinctive features
Allergic conjunctivitis	Primary itching, bilateral, watery or mucous discharge
Viral conjunctivitis	Contagiousness, follicles, preauricular nodes
Bacterial conjunctivitis	Thick pus, sticking of eyelids
Dry eye, blepharitis	Chronicity, meibomian dysfunction, mild itching
Drug-induced variant	Relationship with local preparations and preservatives
Summary - based on systematic reviews and clinical guidelines. [53]

Treatment

The first step is eliminating exposure and non-pharmacological measures. Cold compresses, artificial tears, preferably preservative-free, and avoiding eye rubbing are recommended. Decongestant drops are not considered a long-term solution due to the risk of tachyphylaxis and late hyperemia. [54]

Basic pharmacotherapy consists of topical antihistamines with membrane-stabilizing properties. Drugs with proven efficacy include olopatadine, becpotastine, alcaftadine, and other members of this class. They reduce itching, redness, and lacrimation and are well tolerated with long-term use during the season. [55]

Olopatadine is available in various concentrations. Single-dose regimens are suitable for patients with stable symptoms. 0.7% strength formulations provide daily pruritus control with a single dose, increasing compliance. The choice of specific concentration and frequency of administration is determined by availability and tolerability. [56]

Bepotastin at a concentration of 1.5 percent is typically applied twice daily. It combines antihistamine and membrane-stabilizing effects, demonstrating a clinically significant reduction in itching and associated symptoms. The drug is suitable for both seasonal and year-round use. [57]

Alcaftadine 0.25 percent is applied once daily and has been shown to prevent itching during seasonal exposure. For patients with severe preservative sensitivity, preservative-free forms may be appropriate if available.[58]

If the response to monotherapy is insufficient, it may be advisable to add control of concomitant allergic rhinitis. Current data show that intranasal corticosteroids and intranasal antihistamines improve not only nasal but also ocular symptoms. Combined intranasal formulas demonstrate the greatest overall effect. [59]

Short courses of topical corticosteroids are used for severe exacerbations involving the cornea or for persistent itching. Modern molecules with a favorable safety profile for short-term use under ophthalmologist supervision are preferred. Long-term use without supervision increases the risk of complications. [60]

In cases of recurrent allergic reactions and significant seasonal stress, allergen-specific immunotherapy in the form of subcutaneous or sublingual administration of standardized allergens is considered. This is the only strategy capable of modifying the natural course of allergic disease and reducing the severity of eye symptoms during the season. The decision is made in consultation with an allergist. [61]

Severe forms, including vernal and atopic keratoconjunctivitis, require steroid-sparing regimens. Ophthalmic forms of cyclosporine, proven effective in controlling corneal inflammation and reducing steroid requirements, are used. Treatment is individualized with regular monitoring. [62]

Tacrolimus in ophthalmic formulations and eyelid ointments is considered an alternative or additional steroid-sparing option for refractory severe allergic eye diseases. Regular tolerability monitoring and dose titration enhance safety and durability of effect. [63]

Table 9. Ladder of therapy for allergic conjunctivitis

Step	Measures
Basic	Exposure control, cold compresses, preservative-free artificial tears
First line	Local antihistamines and membrane stabilizers, preferably dual-action drugs
Gain	Control of allergic rhinitis with intranasal agents, avoidance of vasoconstrictor eye drops
Exacerbation	Short course of topical corticosteroids under supervision
Relapses	Allergen-specific immunotherapy according to indications
Severe forms	Cyclosporine ophthalmic, tacrolimus, specialized management
Summary - from manuals and modern reviews. [64]

Table 10. Examples of dual-action topical preparations and typical regimens

Preparation	Approximate diagram
Olopatadine	Once a day at a concentration of 0.7 percent, other regimens are possible depending on the form
Bepotastin 1.5 percent	Twice a day
Alcaftadine 0.25 percent	Once a day
Dosages are confirmed by official instructions and drug databases. The final regimen is determined by the attending physician. [65]

Prevention

Environmental control includes regular wet cleaning, use of vacuum cleaners with high-efficiency filters, reduced humidity to limit mite activity, and limiting contact with animal hair in cases of proven sensitization. These measures reduce the frequency of exacerbations in patients with the perennial form. [66]

During pollen season, it's helpful to keep windows closed during peak pollen concentrations, use air conditioners with filters, and wear sunglasses when outdoors. After returning home, it's recommended to wash your eyelids and eyelashes and change clothes. [67]

Adjusting contact lens care includes reducing wear time seasonally, switching to daily disposable lenses, and carefully monitoring lens case cleanliness. These steps reduce the risk of mechanical irritation and papillary changes. [68]

Patient education to recognize early signs of flare-ups and correct use of preservative-free artificial tears may help reduce the need for anti-inflammatory medications and improve long-term control. [69]

Forecast

For both seasonal and year-round forms, the prognosis is favorable with preventative measures and regular use of topical antihistamines. Most patients achieve sustained symptom control without risk to vision. [70]

In severe cases, the prognosis is largely determined by the timing of initiation of anti-inflammatory therapy and its adequacy. Early initiation of cyclosporine and tacrolimus reduces the risk of corneal damage and the need for corticosteroids. [71]

Long-term reduction in sensitivity is possible with properly selected allergen-specific immunotherapy. This reduces the intensity of seasonal exacerbations and the drug burden, improving quality of life. [72]

Regular monitoring is necessary for patients with contact forms, multi-component topical therapy and those requiring repeated courses of steroids to prevent drug-induced reactions and complications. [73]

Frequently asked questions

Is it possible to treat with only systemic antiallergic tablets?

Oral antihistamines reduce itching, but eye drops with a topical antihistamine and membrane-stabilizing effect are more effective in controlling ocular surface symptoms. A combination approach is optimal for concomitant rhinitis. [74]

Do intranasal nasal sprays help with eye symptoms?

Yes, systematic review data show improvement in both nasal and ocular symptoms with intranasal corticosteroids and intranasal antihistamines, particularly in the seasonal form.[75]

Are vasoconstrictor eye drops dangerous?

With prolonged use, tachyphylaxis and increased redness after discontinuation are possible. They do not eliminate inflammation and should not be used as primary therapy. [76]

When to consider allergen-specific immunotherapy?

In cases of frequent and severe seasonal exacerbations, insufficient response to topical therapy, and confirmed sensitization to a causative allergen, the decision is made in consultation with an allergist. [77]

What should contact lens wearers do if they experience increased itching and thread-like discharge?

Temporarily discontinue wearing, switch to daily disposable lenses when resuming, evaluate care and material, undergo examination to exclude the giant papillary variant. [78]

What role do steroid-sparing agents play?

Cyclosporine and tacrolimus reduce inflammation and the need for corticosteroids in severe cases. Treatment regimen selection and monitoring are performed by an ophthalmologist. [79]