Hay fever conjunctivitis: how it manifests and how it is treated

Pollen allergic conjunctivitis is an inflammation of the conjunctiva that occurs when a sensitized person comes into contact with seasonal plant allergens. The condition is characterized by itching, redness, lacrimation, and a foreign body sensation; both eyes are usually affected. Symptoms often worsen during the flowering season of grasses, trees, or weeds and significantly reduce quality of life, concentration, and productivity in children and adults. [1]

Pollen allergic conjunctivitis is almost always associated with allergic rhinitis, forming so-called allergic rhinoconjunctivitis. This combination is explained by the common immune mechanisms and reflex connections between the nasal mucosa and the ocular surface. During seasonal outbreaks, patients often complain of sneezing, itchy eyes, and nasal congestion. This explains modern interdisciplinary treatment approaches that consider both ocular and nasal symptoms. [2]

Despite its "common" symptoms, this is not a harmless condition. Severe itching triggers vigorous eyelid rubbing, which increases inflammation, disrupts the stability of the tear film, and can lead to microdamage to the epithelium. A small percentage of patients experience corneal complications, especially in the presence of severe atopic diseases of the ocular surface. Timely diagnosis and appropriate treatment significantly reduce symptoms and prevent complications. [3]

In recent years, new data have emerged on the role of epithelial "alarmins"—thymic stromal lymphopoietin, interleukin-33, and interleukin-25—in initiating and maintaining allergic inflammation on the ocular surface. These molecules activate innate and adaptive immune systems, increasing itching, hyperemia, and swelling. Considering these mechanisms helps explain the effectiveness of both topical antiallergic drops and nasal medications that affect the naso-ocular reflex. [4]

Code according to ICD 10 and ICD 11

In clinical practice, codes from the International Classification of Diseases, Tenth Revision and Eleventh Revision are used. For seasonal allergic conjunctivitis, the categories "acute atopic conjunctivitis" and "other chronic allergic conjunctivitis" are most often used. The exact wording depends on the severity and duration of symptoms, as well as the presence of concomitant corneal lesions. When assigning a code, it is important for the physician to indicate the side of the lesion, if required by local variations of the classifier. [5]

The International Classification of Diseases, Eleventh Revision, includes the category "allergic conjunctivitis," which covers both seasonal and year-round forms. The description emphasizes the role of immunoglobulin E and mast cell mediators in pathogenesis, bringing the classification closer to modern understanding of the disease. It is important to use current versions of classifiers, as the wording and hierarchy of categories are periodically refined. [6]

Table 1. Codes for allergic conjunctivitis

System	Heading	How to use
ICD 10	H10.1 "Acute atopic conjunctivitis"	Indicates acute course; some implementations may provide detail by eye side
ICD 10	H10.45 "Other chronic allergic conjunctivitis"	Used for longer duration and recurring episodes
ICD 11	9A60.02 "Allergic conjunctivitis"	Combines seasonal and year-round forms within the framework of conjunctival diseases

[7]

Epidemiology

Allergic eye diseases are very common. Several reviews estimate the prevalence of ocular allergies in the population to be between 6% and 20%, and in adolescents, the incidence of rhinoconjunctivitis symptoms reaches 14%-16%, according to large global studies. Significant differences are associated with climate, pollen seasons, and survey methods. [8]

Childhood cohorts exhibit a high disease burden: studies from the Global Asthma and Allergy Network have noted that rhinoconjunctivitis symptoms in adolescents are common, ranging from 1% to 45% depending on the region. Gender and age variability are also observed, and seasonality closely coincides with the pollen seasons of dominant plant species. [9]

In countries with pronounced seasonality in grass and tree pollen, the proportion of seasonal cases of ocular allergy is highest. In school samples, seasonal conjunctivitis can account for up to 80%-90% of all clinically diagnosed allergic conjunctivitis cases. These figures underscore the importance of prevention and early treatment during the pre-season period. [10]

Allergic conjunctivitis significantly reduces the quality of life of children and their parents, affecting sleep, schoolwork, and daily activities. Validated questionnaires show a significant deterioration in scores during the pollen season compared to the off-season. This justifies an active patient management strategy, especially in regions with long pollen seasons. [11]

Table 2. Reference prevalence rates

Parameter	Range
Prevalence of eye allergies in the population	6%-20%
Symptoms of rhinoconjunctivitis in adolescents	14%-16% on average, 1%-45% in centers
The proportion of seasonal forms among clinical cases in schoolchildren	Up to 80%-90%

[12]

Reasons

The primary cause of the disease is contact of a sensitized organism with pollen allergens from trees, grasses, or weeds. In a sensitized patient, immunoglobulin E antibodies are present on the surface of the mast cells of the conjunctiva, recognizing specific proteins in pollen. Repeated exposure to the allergen triggers a cascade of histamine and other inflammatory mediators, causing itching, redness, and lacrimation. [13]

The seasonality of symptoms is directly related to the pollen calendar. In regions with multiple peak periods, a single patient may experience repeated flare-ups in summer and fall if the sensitization includes grasses and weeds. It is important to consider cross-reactions between allergens from different plants, which explains the symptoms occurring over a wider season. [14]

In addition to exoallergens, environmental factors such as the concentration of fine particles, ozone, and other pollutants influence the severity of the reaction. These factors increase ocular surface inflammation and increase epithelial permeability, facilitating allergen access to target cells. This partially explains the differences in symptom severity between equally sensitized individuals. [15]

The association with allergic rhinitis is due to both a common immune substrate and the naso-ocular reflex: stimulation of the nasal mucosa by an allergen can reflexively exacerbate ocular symptoms. Therefore, treatment focuses not only on eye drops but also on controlling nasal symptoms. [16]

Risk factors

Strong predictors include family history of atopy and a personal history of atopy. Children with atopic dermatitis and food sensitivities are more likely to develop allergic rhinoconjunctivitis during school age. The presence of bronchial asthma also increases the likelihood of severe eye symptoms during pollen seasons. [17]

Air pollution and high dust levels increase ocular surface inflammation by reducing the barrier function of the epithelium. Combined with widespread exposure to allergens, this leads to a more severe course and more frequent exacerbations. Patients living near busy highways often report more persistent itching and hyperemia. [18]

Contact lenses and poor eyelid hygiene increase the risk of persistent conjunctival irritation, which can mask or exacerbate allergic symptoms. Seasonal lens use during high pollen loads is often accompanied by decreased tolerance and increased symptoms. This should be taken into account when choosing lenses during pollen season. [19]

Age and gender also influence the clinical picture: in adolescents and young adults, symptoms are often most pronounced, while in school-aged children, allergies significantly contribute to a reduced quality of life. Genetic predisposition and early sensitization create a window of vulnerability that is important to recognize for prevention. [20]

Table 3. Risk factors and strength of association

Factor	Nature of the connection
Family history of atopy, personal history of atopy	Strong
Allergic rhinitis and bronchial asthma	Strong
Air pollution, high pollen levels	Moderate to strong
Wearing contact lenses during pollen season	Moderate
Childhood and adolescence	Moderate

[21]

Pathogenesis

Upon initial contact with an allergen, the ocular mucosa initiates the sensitization process. Epithelial cells secrete thymic stromal lymphopoietin, interleukin-33, and interleukin-25, which activate dendritic cells and innate lymphoid cells. This leads to the development of a predominance of type 2 T-helper cells and the synthesis of immunoglobulin E antibodies by plasma cells. [22]

Upon repeated exposure to the allergen, IgE antibodies on the surface of mast cells initiate the immediate phase: histamine, tryptase, and other mediators are released, causing itching, hyperemia, and conjunctival edema. Hours later, the late phase develops with the recruitment of eosinophils and increased inflammation, which maintains symptoms and increases the sensitivity of itch receptors. [23]

The naso-ocular reflex plays a key role: an allergic reaction in the nasal cavity can reflexively exacerbate ocular symptoms through neurogenic mechanisms. This explains the clinical effect of intranasal glucocorticosteroids on ocular manifestations in some patients. Managing this reflex is considered one way to optimize treatment. [24]

Additional molecular components include interleukin-31, which is associated with itching sensation, and disruption of the epithelial barrier. These factors exacerbate clinical manifestations and explain why eye drop formulations and the presence of preservatives affect the tolerability and efficacy of therapy. [25]

Symptoms

The classic triad is itching, redness, and lacrimation. Patients often describe a burning sensation and a gritty feeling in the eyes. Symptoms occur quickly after exposure to the allergen and are often accompanied by sneezing, rhinorrhea, and nasal congestion. Both eyes are typically affected, although the intensity may vary. [26]

Itching is the most characteristic symptom. It provokes frequent eyelid rubbing, which aggravates the inflammation and can lead to microtrauma to the epithelium. Examination reveals diffuse conjunctival injection, mild edema, and watery discharge. Pain and purulent discharge are uncommon and suggest a different cause. [27]

In some patients, symptoms are predominantly pronounced during daylight hours when outdoors, and are alleviated indoors with filtered air. Discomfort increases in windy weather and while working outdoors. Wearing contact lenses during the season often reduces tolerance and increases itching. [28]

In severe cases, photophobia and decreased visual acuity are possible due to tear film instability. Corneal damage is uncommon in the seasonal form, but may occur with the overlap of other atopic diseases of the ocular surface. In such cases, a specialist examination and an expanded treatment plan are necessary. [29]

Table 4. The most common complaints and examination signs

Complaint or symptom	Typical for pollen allergic conjunctivitis
Itching	Very high
Redness and tearing	High
Watery discharge	High
Photophobia, decreased visual acuity	Low, requires exclusion of complications
Purulent discharge, severe pain	It's unusual to think of another reason.

[30]

Classification, forms and stages

Allergic diseases of the conjunctiva are divided into seasonal and year-round forms, as well as more severe chronic forms such as vernal keratoconjunctivitis and atopic keratoconjunctivitis. The seasonal form is the most common and is associated with pollen periods. The year-round form is caused by persistent indoor allergens. [31]

Severity is classified as mild, moderate, and severe. Mild cases are limited to itching and moderate redness and do not interfere with daily activities. Moderate cases are accompanied by significant discomfort and affect school or work. Severe cases involve significant symptoms, possible corneal damage, and the need for specialized therapy. [32]

In clinical practice, it is important to distinguish the seasonal form from vernal and atopic keratoconjunctivitis, as the latter pose a risk to the cornea and require different management. The age of onset, the presence of large papillae on the upper eyelid, and persistent itching are often helpful. Suspicion of these forms is grounds for referral to a specialist. [33]

There is no standard "stage" for the seasonal form, but there are distinct exacerbation and remission phases closely linked to the pollen calendar. During the off-season, secondary prevention strategies are useful, including allergen-specific immunotherapy in selected patients with proven sensitization. [34]

Complications and consequences

If itching is not fully controlled, constant eyelid rubbing leads to chronic inflammation, deterioration of tear film stability, and increased discomfort. This creates a "vicious cycle" of itching and inflammation. This can lead to increased sensitivity to contact lenses and cosmetics. [35]

Rarely, keratopathy with punctate epithelial defects may develop, especially in patients with severe atopic diseases of the ocular surface. Such changes are accompanied by photophobia and decreased visual acuity and require a review of therapy, including topical immunosuppressive agents. [36]

Excessive and prolonged use of vasoconstrictor drops can cause a rebound phenomenon with persistent hyperemia. This leads to dependence on fast-acting drops and worsens symptom control. Patients should be advised of the risks and limit the duration of use of such medications. [37]

The disease significantly reduces quality of life, impacts sleep and cognitive function in children and adolescents, and affects parental satisfaction. Therefore, the goal of therapy is not only to relieve acute symptoms but also to restore normal activity during pollen seasons. [38]

When to see a doctor

Daily itching and redness of the eyes during pollen season are a reason to seek medical attention, especially if the symptoms interfere with school or work. A medical assessment can distinguish allergic causes from infections and select safe medications with proven efficacy. Self-medication with vasoconstrictor drops without supervision is not recommended. [39]

Immediate treatment is necessary if severe pain, blurred vision, photophobia, purulent discharge, or if one eye is affected and rapidly worsens. These signs are atypical for simple seasonal ophthalmia and require the exclusion of keratitis, uveitis, or bacterial infection. [40]

If symptoms persist beyond the pollen season or recur almost year-round, a reassessment of the diagnosis is necessary. In this case, consideration should be given to a perennial form, contact irritants, eyelid hygiene problems, contact lens intolerance, or toxic effects of preservatives. [41]

Patients with a combination of severe rhinitis and eye symptoms may benefit from consultation with an allergy specialist to discuss allergen-specific immunotherapy. This approach can reduce the severity of eye symptoms and the need for symptomatic drops. [42]

Diagnostics

The first step is a detailed collection of complaints and anamnesis, linking symptoms to seasons, findings during outdoor activities, and possible triggers. The presence of rhinitis, atopic diseases, and reactions to contact lenses is clarified. The doctor assesses the impact on quality of life and academic or work performance. [43]

The second step is biomicroscopy: the degree of injection, conjunctival edema, and the nature of the discharge are assessed. Large papillae of the upper eyelid are noted, which are atypical for simple seasonal rosacea and suggest more severe atopic variants. Unilaterality and purulent discharge require the exclusion of infections. [44]

The third step is confirmation of sensitization in cases of prolonged or recurrent disease: skin prick tests or specific IgE antibodies to suspected pollen allergens in serum. These methods help select allergen-specific immunotherapy and provide a basis for pre-season prophylaxis. Provocative conjunctival tests are used rarely and in specialized settings. [45]

The fourth step is an assessment of concomitant conditions and factors that interfere with treatment: severe rhinitis, chronic eyelid diseases, and preservative intolerance. This comprehensive assessment allows for optimization of the regimen based on the naso-ocular reflex and selection of medications with better tolerability. [46]

Table 5. Diagnostic tactics

Stage	Target	Comment
Anamnesis	Identify seasonality, triggers, and combinations with rhinitis	Record the impact on activity
Inspection	Confirm characteristic signs	Pay attention to the discharge and papillae
Sensitization tests	Confirm causative allergens	Important for immunotherapy
Assessment of associated factors	Find barriers to treatment	Consider the naso-ocular reflex and tolerance

[47]

Differential diagnosis

Viral and bacterial conjunctivitis often mimic redness and discomfort, but they are typically unilateral in onset, with sticky or purulent discharge, severe pain, and a lack of characteristic itching. Indiscriminate use of antibacterial drops for allergic reactions is unhelpful and carries risks. [48]

Dry eye syndrome causes a burning and gritty sensation, but itching is less pronounced and there is usually no seasonal association. Osmotic testing and assessment of tear film stability help differentiate these conditions. When allergies and tear film deficiency coexist, treatment strategies should address both issues. [49]

Contact and toxic conjunctivitis are associated with cosmetics, cleaning products, and preservatives in eye drops. They are characterized by an increase in symptoms after contact with a specific substance and a decrease upon discontinuing exposure. A thorough history and rational elimination of suspected factors are essential. [50]

Severe atopic forms—vernal and atopic keratoconjunctivitis—are accompanied by corneal lesions, massive papillae, filiform mucus, and severe photophobia. Suspected cases of these conditions require referral to a specialist for the selection of anti-inflammatory and immunosuppressive therapy. [51]

Table 6. Differences between common ocular surface conditions

State	Itching	Separable	Seasonality	Pain	Cornea
Pollen allergic conjunctivitis	Expressed	Watery	Yes	None or minimal	Without defeat
Viral conjunctivitis	Moderate	Watery, mucous	No	Possible	Often does not suffer
Bacterial conjunctivitis	Weak	Purulent	No	Possible	Rarely affected
Dry eye syndrome	Moderate	Meager	No	Burning	Punctate keratopathy
Vernal keratoconjunctivitis	Very pronounced	Mucous	Partially	Possible	Often affected

[52]

Treatment

Basic non-drug treatment includes cold compresses, preservative-free artificial tears, and a strict ban on eye rubbing. Sunglasses and temporary restrictions on contact lens wear during pollen season are also helpful. These simple measures reduce strain on the ocular surface and improve comfort. [53]

First-line medications include topical antihistamines and mast cell stabilizers, as well as "dual-action" drops that combine both mechanisms. This group includes olopatadine, ketotifen, alcaftadine, bepotastine, and others. Their effectiveness in reducing itching and hyperemia has been confirmed by systematic reviews and guidelines. The choice of a specific medication depends on availability, tolerability, and individual response. [54]

Comparative studies in recent years show similar overall efficacy among these groups, with some studies favoring bepotastine or alcaftadine in terms of the speed and severity of reduction in itching and hyperemia. Regular use and initiation of therapy immediately upon the onset of seasonal symptoms are more important. [55]

Decongestant drops provide short-term relief of redness, but do not affect inflammation and, with prolonged use, cause a rebound effect with persistent hyperemia. They should be avoided or used for extremely short periods. Patients should be advised of these limitations to avoid developing a dependence on fast-acting drops. [56]

In some patients, intranasal glucocorticosteroids also reduce ocular symptoms by influencing the naso-ocular reflex. This is particularly useful in cases of severe combined rhinitis. These medications do not enter the eye and have a favorable safety profile when administered correctly. [57]

Short courses of topical ocular glucocorticosteroids are reserved for severe symptoms not controlled by first-line treatments. They rapidly reduce inflammation but require specialist monitoring due to the risk of increased intraocular pressure and other adverse effects. They should be used for the minimum required course. [58]

For severe atopic forms with corneal damage, topical immunosuppressants such as cyclosporine or tacrolimus are used to reduce the need for hormonal medications and prevent relapses. For purely seasonal forms, such agents are usually not required, but they can be useful in mixed cases. The decision is made by a specialist. [59]

Allergen-specific immunotherapy is an option for patients with proven sensitization and inadequate symptomatic control. Sublingual tablets and subcutaneous injections can reduce the severity of rhinitis and eye symptoms following exposure to the causative pollen. The effect develops gradually and requires a course of treatment. [60]

The composition of eye drops matters: the presence of preservatives can reduce tolerability with frequent use. Selecting preservative-free solutions and optimal bottle sizes helps reduce ocular surface irritation and improve compliance. This is especially important with repeated daily use during the season. [61]

Comprehensive management includes patient education: a seasonal action plan, proper drop instillation technique, rhinitis control, and avoidance of triggers. This approach is consistent with modern integrated care pathways for patients with allergic diseases of the respiratory tract and ocular surface. [62]

Table 7. Main therapy groups

Group	Exemplary representatives	Mechanism	Peculiarities
Antihistamines and mast cell stabilizers, "dual-action" agents	Olopatadine, ketotifen, bepotastine, alcaftadine	Blockade of histamine effects and stabilization of mast cells	First line in seasonal uniform
Intranasal glucocorticosteroids	Mometasone, fluticasone	Suppression of inflammation in the nasal cavity and influence on the naso-ocular reflex	Useful for severe rhinitis
Topical ocular glucocorticosteroids	Different	Rapid anti-inflammatory action	Short courses under the supervision of a specialist
Local immunosuppressants	Cyclosporine, tacrolimus	Modulation of the immune response	Reserve for severe atopic forms
Allergen-specific immunotherapy	Sublingual tablets, subcutaneous injections	Tolerance induction	Course treatment in selected patients

[63]

Prevention

During pollen season, it's important to minimize exposure to allergens: close windows during peak pollen hours, use indoor air filtration, wear protective eyewear outdoors, and, if possible, move exercise indoors. After returning home, it's helpful to rinse your eyes with artificial tears to remove any remaining pollen. [64]

A seasonal prevention plan includes early initiation of antihistamine drops at the first sign of increased pollen load. Patients with recurring severe seasons should discuss allergen immunotherapy several months before the expected peak. This strategy reduces the severity of symptoms and the need for rescue medications. [65]

Allergen control in the home is also important for seasonal allergies, as pollen particles brought in from outdoors settle in the home. Regular wet cleaning and washing eyelashes and eyelid margins with gentle eyelid cleansers help reduce ocular surface irritation. If contact lenses are poorly tolerated during the season, it's best to switch to glasses. [66]

Patient and family education improves adherence and reduces the risk of unnecessary use of decongestants. Understanding the role of the naso-ocular reflex helps explain why rhinitis treatment improves ocular symptoms and motivates regular use of nasal medications in appropriate patients. [67]

Table 8. Practical steps for prevention

Situation	What to do
Peak of dusting	Limit time spent outdoors, use glasses
Returning home	Rinse your eyes with artificial tears and wash your face.
Sport	Give preference to rooms with air filtration
Wearing optics	Prefer glasses during the season or use lenses sparingly

[68]

Forecast

For most people, the prognosis is favorable: symptoms are effectively controlled with a combination of non-drug measures and modern topical medications. With proper treatment, the number of days with severe itching and redness decreases, and sleep and overall activity during pollen season improve. [69]

A small group of patients with atopic ocular surface diseases may experience recurrent severe exacerbations requiring highly specialized therapy. Early recognition of these forms and access to topical immunosuppressive agents significantly reduce the risk of corneal damage. [70]

Allergen-specific immunotherapy can modify the course of the disease in cases of proven sensitization to specific pollens. When administered correctly, it reduces the severity of eye symptoms during the season and decreases the need for symptomatic eye drops. [71]

The key to success is a personalized plan for the season, including prevention, timely initiation of drops, and rhinitis control. This "roadmap" should be taught to patients in advance to minimize the "acceleration" of symptoms once the season begins. [72]

Frequently asked questions

Is it possible to treat the condition with artificial tears and cold compresses alone?
This may help with mild symptoms, but if the itching and redness are severe, topical antihistamines or "dual-action" medications are needed. Long-term use of decongestant drops on your own is not recommended due to the risk of rebound. [73]

Will nasal sprays help with eye irritation?
Yes, in some patients, intranasal glucocorticosteroids also reduce eye symptoms by influencing the naso-ocular reflex. This is especially helpful for severe rhinitis. [74]

When should allergen-specific immunotherapy be considered?
If seasonal exacerbations recur annually and severe symptoms persist despite symptomatic therapy. Immunotherapy is indicated for proven sensitization to specific pollen and is administered in courses. [75]

Do all patients need hormonal drops?
No. Short courses of topical glucocorticosteroids are used only during severe exacerbations under the supervision of a specialist. Their purpose is to quickly reduce inflammation, after which the maintenance regimen is returned. [76]

Why shouldn't you just "drip" any vasoconstrictors onto redness?
Because they don't treat inflammation, and long-term use causes persistent hyperemia. This worsens disease control and leads to dependence. It's better to use products with proven anti-allergic properties. [77]

Table 9. Red flags and actions

Sign	Possible cause	What to do
Severe pain, photophobia, decreased visual acuity	Corneal lesion, keratitis	See an ophthalmologist urgently
Unilateral lesion with purulent discharge	Bacterial infection	Examination, etiotropic therapy
No seasonality, year-round symptoms	Year-round form, contact irritants	Advanced diagnostics
Persistent relapse after "redness drops"	The "ricochet" phenomenon	Discontinuation of vasoconstrictors, change of regimen

[78]