Allergic conjunctivitis is often caused by aeroallergens. The main categories are pollen, dust mites, mould spores, and domestic dust. Birch pollen, alder, oak, grasses, ragweed, and mugwort are the most powerful plant allergies. Pollen grains in the air increase during these plants’ flowering season, causing widespread allergy reactions. Poplar fluff (Populus trichocarpa) is commonly mistaken for a severe allergen, but it can carry pollen from other plants and dust particles that cause allergy reactions. Poplar fluff does not cause allergies, although it may irritate and create allergic symptoms in sensitive people. Dust mites Dermatophagoides pteronyssinus and farinae are the main cause of allergic sensitisation because their excrement contains proteins (Der p 1, Der f 1) that trigger immunological responses. Aspergillus fumigatus, Cladosporium herbarum, Penicillium chrysogenum, and Alternaria alternata produce mould spores, another common allergen.⁽⁴⁾ These microbes love damp soil, food, and overripe produce. Dust mites, silk and cotton fibres, animal hair and skin, and microscopic wood particles make household dust an allergy.

Contact allergens are critical to the development of visual organ allergic reactions owing to direct chemical or biological irritating exposure. Such compounds might cause localised allergic reactions such itching, redness, lacrimation, and eyelid swelling, lowering patients’ quality of life. Cosmetics are a common trigger. Parabens and aromatic compounds like citronellol and limonene, used in facial treatments, makeup removers, eyeshadows, and mascaras, might cause hypersensitivity. Colour pigments like zinc and titanium oxides can also cause skin and eye mucosal irritation and inflammation.

Pharmaceuticals used in ophthalmology can be sensitising due to allergenic components. Ophthalmic solution preservative benzalkonium chloride has been linked to eye irritation. Beta-blockers like timolol and antibiotics like chloramphenicol and gentamicin can also cause sensitisation. Even ocular hydration products like artificial tears might cause allergy reactions if they contain allergenic excipients.

Contact lenses and maintenance items also contribute to ocular allergies. With continuous use, silicone hydrogel polymers in lenses may cause hypersensitivity. Lens cleaning solutions with strong chemicals like hydrogen peroxide or PAPB can worsen these reactions. Improper lens maintenance strains the ocular mucosa, increasing discomfort and allergic reactions.

Certain food allergies can cause ophthalmologic symptoms. Food sensitisation can cause eyelid puffiness and redness. Almonds and cashews include the strong allergenic proteins Ara h 1 and Ara h 2.

Tropomyosin, a protein in prawns, oysters, and squid, is a common seafood allergy. Milk and eggs, two of the most common dietary triggers in children, cause sensitisation through casein and beta-lactoglobulin and ovalbumin and ovomucoid proteins.⁽⁶⁾ Pollen allergen-protein cross-reactivity in food is also essential. Birch pollen-sensitive people may be allergic to apples, peaches, kiwis, celery, and tomatoes.

Chemical allergies affect eye health, especially in polluted areas. The furniture and construction industry uses formaldehyde, a powerful irritant. Long-term exposure to this chemical may cause conjunctival redness and irritation. PM 2.5 and nitrogen oxides from vehicle exhaust can penetrate ocular tissues and cause inflammation.⁽¹⁾ Resins and paint coats release allergenic volatile chemicals into the air, triggering sensitisation. Tobacco smoke contains ammonia, acetone, and phenols, which can worsen sensitisation reactions and increase mucous membrane permeability to other agents.

Saliva, hair, and dander proteins can cause allergic responses. In particular, Fel d 1, a protein in cat saliva and fur, causes most home allergies. Horse Equ c 1 and dog Can f 1 have similar allergenic characteristics. Dust mite and bee (Api m 1) and wasp (Ves v 5) allergens can cause eyelid oedema and conjunctival irritation.⁽⁷⁾

Understanding each allergen type is essential for developing effective diagnostic and preventive methods for allergic ocular disorders. In conclusion, aeroallergens, contact agents, dietary proteins, chemical pollutants, and animal-derived particles cause ocular allergy reactions, which must be identified to develop appropriate management techniques.

A review of the literature identified that the effects of major allergen groups are mediated by complex immunopathogenetic mechanisms that activate the immune response. Particular emphasis was placed on environmental allergens, which are among the most common triggers.

According to systematic sources, pollen from ragweed, birch, and grasses induces acute inflammatory responses via IgE-mediated sensitisation, resulting in an increase in serum IgE levels to 200 to 500 kU/L in sensitised individuals.^(4,8) Upon allergen exposure, mast cells become activated and release mediators such as histamine (1.2 to 1.8 ng/mL), prostaglandins, and leukotrienes. This process is key to the development of primary symptoms, including itching, conjunctival redness, and lacrimation.⁽⁸⁾

Contact allergens, including cosmetic products and ophthalmic medications, tend to provoke prolonged allergic reactions, frequently associated with delayed-type hypersensitivity. Substances such as benzalkonium chloride, commonly used in eye drops, contribute to inflammatory processes by activating T lymphocytes, which, in turn, induce delayed eyelid oedema and irritation of the ocular mucosa. Studies have shown that benzalkonium chloride increases intercellular adhesion molecule (ICAM)-1 expression on endothelial cells by three- to fivefold, thereby promoting the migration of inflammatory cells into the conjunctiva.^(4,6)

The immune mechanisms underlying allergic reactions that manifest as ophthalmic symptoms exhibit specificity depending on the type of allergen, target cells, and the molecular pathways involved. IgE-mediated immune response is the predominant mechanism in the pathogenesis of allergic conjunctivitis, particularly in response to aeroallergens.^(4,9) This reaction develops in two distinct phases. During the initial exposure to an allergen, sensitisation occurs through the activation of antigen-presenting cells (dendritic cells and macrophages), which present the allergen's antigen on major histocompatibility complex (MHC) class II molecules. This information is relayed to type 2 T-helper (Th2) cells, which subsequently produce cytokines interleukin (IL)-4 and IL-13, stimulating B-lymphocyte differentiation and the production of specific IgE (IL-4 levels increase by a factor of 2-3, and IL-13 by 1.5-2).⁽⁹⁾ These antibodies bind to high-affinity FcεRI receptors on the surface of mast cells, forming a sensitised complex.

Upon subsequent exposure to the allergen, cross-linking of IgE on the surface of mast cells induces their degranulation. This results in the release of key inflammatory mediators, including histamine, tryptase (1.5 to 2.5 ng/mL), prostaglandins, leukotrienes, and cytokines. Histamine interacts with H1 receptors in the vascular endothelium, leading to vasodilation, hyperaemia, oedema, and pruritus, which are the hallmark symptoms of allergic conjunctivitis.⁽⁹⁾ This mechanism is responsible for the acute symptoms of allergic reactions, such as itching, lacrimation, and conjunctival hyperaemia. Aeroallergens, including birch pollen and house dust mites, are the most common triggers of IgE-mediated reactions.^(4,9)

Delayed-type hypersensitivity (classified as type IV hypersensitivity according to the Coombs and Gell classification) is mediated by T lymphocytes, particularly CD4+ (Th1) and CD8+ cells, which orchestrate a cellular immune response. This reaction is most associated with contact allergies.

Following the penetration of allergens, such as components of cosmetic products or ophthalmic medications, into the eyelid skin or conjunctival mucosa, dendritic cells present the antigen to T cells. Th1 cells subsequently release cytokines, including interferon-gamma (IFN-γ) and tumour necrosis factor-alpha (TNF-α), which activate macrophages and other immune cells, thereby promoting inflammation. In the effector phase of the immune response, cytotoxic CD8+ cells induce apoptosis in target cells, leading to localised tissue damage. This mechanism explains the delayed onset of symptoms, including eyelid oedema, pronounced irritation, and pruritus. Delayed-type hypersensitivity is frequently associated with prolonged use of pharmaceutical agents (e.g., eye drops containing preservatives) or contact lenses.^(6,8)

Cytokine-mediated inflammatory reactions represent a universal mechanism accompanying all allergic responses. Interleukins, particularly IL-4, IL-5, and IL-13, play a central role in this process, being activated through the involvement of Th2 cells. IL-4 and IL-13 enhance IgE production, while IL-5 is responsible for eosinophil activation. The activation of eosinophils leads to the release of toxic proteins, such as major basic protein (MBP, 0.5 to 1.2 ng/ml) and eosinophilic cationic protein (ECP, 5 to 15 ng/ml), which cause damage to the conjunctival epithelium. These processes sustain and prolong allergic inflammation, contributing to chronic allergic conjunctivitis or keratoconjunctivitis.⁽⁹⁾

Elevated levels of pro-inflammatory cytokines, such as TNF-α and IL-1β, further promote vascular endothelial activation, thereby enhancing the recruitment of immune cells to the site of inflammation. Key aspects of this type of reaction include the increased levels of cytokines (IL-4, IL-5, IL-13) observed in patients with chronic allergic conjunctivitis and the fact that this mechanism plays a crucial role in persistent allergic conditions associated with structural alterations in the mucosal epithelium (Table 1).

An analysis of the mechanisms underlying allergic reactions that lead to ophthalmic manifestations demonstrates certain patterns in the relationship between allergen types and the clinical symptoms experienced by patients. Key factors that may modulate this relationship include the level of patient sensitisation, genetic predisposition, comorbidities, and environmental factors such as air pollution levels. Aeroallergens (pollen, mites, fungal spores) most commonly trigger IgE-mediated reactions. These manifest as acute symptoms such as itching, lacrimation, and conjunctival hyperaemia, which are characteristic signs of allergic conjunctivitis. In patients with high sensitisation levels or a genetic predisposition to allergies, these symptoms may be more pronounced, particularly during seasonal pollen exposure.

Contact allergens, such as cosmetic products and ophthalmic preparations, are more likely to induce delayed-type hypersensitivity, resulting in chronic symptoms such as eyelid oedema and irritation of the ocular mucosa, significantly affecting patients’ quality of life. Prolonged use of these substances may increase the frequency of such reactions. Food allergens may also be associated with ophthalmic manifestations, including pronounced eyelid oedema and itching around the eyes. These reactions are particularly pronounced in cases of cross-reactivity with pollen allergens, such as birch pollen. Patients with this type of sensitisation may experience allergic symptoms not only upon exposure to pollen but also following the ingestion of certain foods. Chemical pollutants, such as vehicle emissions or household chemical components, have the potential to activate the cytokine cascade, provoking inflammation and chronic ocular irritation. Patients residing in areas with high levels of pollution tend to exhibit more pronounced symptoms, which may be compounded by other allergic reactions, leading to chronic forms of conjunctivitis.

Research indicates that the level of sensitisation, as determined by the concentration of specific IgE antibodies in serum, serves as a key predictor of the severity of allergic reactions and their ophthalmological manifestations. For instance, elevated levels of specific IgE to ragweed pollen (> 17.5 kU/L) have been associated with more pronounced conjunctival hyperaemia and lacrimation.^(4,8) High concentrations of IgE also correlate with increased levels of ECP in tear fluid, indicating enhanced eosinophil involvement in the pathogenesis of allergic inflammation.⁽⁹⁾ This supports the observation that patients with high levels of sensitisation exhibit more severe clinical symptoms and face an increased risk of persistent or chronic forms of allergic conjunctivitis.⁽⁸⁾

Beyond immunological factors, genetic predisposition and comorbid conditions, such as bronchial asthma and atopic dermatitis, play a crucial role in the severity of ophthalmological manifestations. In patients with concurrent asthma, the concentration of IL-4 and IL-13 in tear fluid is reported to be two to three times higher than in patients without coexisting allergic conditions.⁽⁹⁾ Furthermore, individuals residing in urban areas with exposure to elevated concentrations of fine particulate matter (PM2.5 > 35 μg/m³) demonstrated increased levels of TNF-α and IL-1β in tear fluid, exacerbating inflammatory responses on the ocular surface.⁽¹³⁾

These findings highlight the influence of environmental factors on the development and severity of allergic reactions in ophthalmology. To summarise, the specific clinical manifestations and severity of ocular allergies are dictated by the underlying immune mechanism, ranging from acute IgE-mediated responses to delayed T-cell hypersensitivity, and are significantly modulated by patient sensitisation levels, genetic predisposition, and environmental exposures.

Cross-reactive allergy is a complex immunological phenomenon that arises due to structural similarities between proteins from different allergens. The immune system, recognising these similar molecules as identical antigens, mounts a comparable response even when they originate from distinct sources. This phenomenon has been extensively investigated in the context of interactions between pollen and food allergens. However, food allergens exhibit diverse properties that influence their potential to trigger cross-reactive responses, with thermal processing emerging as a potential strategy for mitigating allergic manifestations.

Cross-reactive allergy is triggered by structural similarities between proteins from different allergens, frequently involving interactions between seasonal pollen and food items. The immune system recognises structurally similar molecules as identical antigens, inducing an allergic reaction even in the absence of direct contact with the primary allergen. The key cross-reactive links and their seasonal dependencies are summarised in table 2.

Studies confirm that the severity of cross-reactive allergies is directly correlated with the concentration of the primary allergen in the environment.^(14-16) During peak pollen seasons (April to May for trees, June to July for grasses), individuals demonstrate increased susceptibility to cross-reactions, even at minimal exposure to dietary triggers. For instance, during ragweed pollen season, clinical symptoms following melon consumption may be more pronounced than out of season, despite identical allergen intake. Seasonality further establishes an optimal setting for the development of multifactorial allergic responses. In pollen-sensitised individuals, additional triggers, such as chemical pollutants or contact with domestic animals, exacerbate the inflammatory response. This is particularly relevant in urbanised areas, where natural allergens are compounded by exposure to vehicle emissions and fine particulate matter.

The identification of seasonal dynamics in allergic manifestations requires a detailed medical history and the application of specific allergy diagnosing methods. The most informative approach involves determining the levels of specific IgE antibodies to seasonal pollen allergens and cross-reactive food components. Effective patient management can be achieved through the use of antihistamines and topical mast cell stabilisers, the development of an individualised elimination diet plan during high-risk seasons for cross-reactive responses, and the administration of allergen-specific immunotherapy (ASIT) to reduce sensitivity to major pollen allergens.⁽¹⁷⁾ Cross-reactive allergy complicates the diagnosis and treatment of patients with ophthalmological manifestations of allergic diseases. A thorough analysis of the structural similarity of proteins and an understanding of the mechanisms underlying secondary allergens are essential. During peak pollen seasons, such as the flowering periods of birch, ragweed, or mugwort, the immune system of sensitised individuals remains in a state of heightened activity. Elevated airborne pollen concentrations activate large numbers of mast cells and basophils, leading to the extensive release of inflammatory mediators such as histamine, prostaglandins, and leukotrienes. This creates a "hyperactive immune background", in which even structurally similar proteins present in minimal amounts (e.g., in food) are recognised by the immune system as threats. For instance, the Bet v 1 protein in birch pollen actively interacts with IgE antibodies bound to mast cells. During this period, even a small amount of Mal d 1 from apples may enhance mast cell degranulation, triggering ophthalmic symptoms associated with cross-reactive allergic responses. Understanding the mechanisms of such reactions is crucial for effective treatment and symptom prevention. Personalised approaches to diagnosis and management can improve the quality of life for affected individuals.^(14,15,17)

In conclusion, cross-reactivity between pollen and food allergens substantially complicates the clinical picture of ocular allergies, driven by structural protein similarities and seasonal exposure spikes. Recognising these cross-reactive patterns is therefore essential for implementing effective, personalised dietary and therapeutic interventions.

The distribution of ophthalmic symptoms among patients with allergic reactions is a key area of research in allergology and ophthalmology. A review of existing literature identified the most common manifestations and their relationship with specific allergen types.^(18-20) Such insights facilitate a better understanding of pathological processes and support the development of individualised treatment strategies.

Ophthalmic symptoms are common manifestations of allergic reactions and can impact patients’ quality of life. The most frequently observed symptoms include itching, conjunctival redness, and lacrimation, which are associated with various allergen groups, including pollen, household, and food allergens. In some cases, severe eyelid oedema may occur, necessitating particular ophthalmological attention. The frequency and characteristics of these symptoms are influenced by the type of allergen involved (Table 3).

Analysis of findings enabled not only the identification of the primary ophthalmic symptoms caused by allergens but also the development of a practical diagnostic algorithm. This algorithm aims to improve the diagnosis of ophthalmic allergies, reduce the time required for identifying the underlying causes of symptoms, and optimise treatment strategies. The diagnostic approach is based on a combination of thorough medical history collection, physical examination, and laboratory testing. The analysis of common ophthalmic symptoms enabled the development of a practical, five-step diagnostic algorithm aimed at reducing identification time and optimising treatment strategies for ophthalmic allergies. The recommended clinical approach is outlined in table 4.

Based on the synthesis of available data, it is recommended that a comprehensive analysis of common allergens and timely screening tests be conducted, particularly for patients with systemic allergies or elevated IgE levels. Treatment should encompass pharmacological management, including antihistamines, topical mast cell stabilisers (e.g., sodium cromoglicate), and, where necessary, topical corticosteroids. Immunotherapy is indicated for patients with confirmed sensitisation, such as ASIT. Preventive measures should focus on minimising exposure to triggering allergens and optimising living conditions (e.g., air purification, reducing exposure to dust mites). Therefore, a detailed analysis of the mechanisms underlying ophthalmological symptoms not only enhances diagnostic approaches but also improves the efficacy of prevention and treatment strategies, ultimately reducing the overall burden on patients with allergic diseases.

The studies on allergic reactions and ophthalmological manifestations provide both confirmation and an expanded understanding of the mechanisms underlying allergic responses, their triggers, and clinical manifestations. Hemmer et al.⁽²²⁾ highlighted the correlation between sensitisation to animal allergens and exposure to domestic pets. Their study also indicates a higher prevalence of sensitisation among pet owners, underscoring the importance of considering this factor in the diagnosis and prevention of allergies. Furthermore, Muñoz et al.⁽²³⁾ examined reactive dye allergens, which are significant in occupational settings. The results revealed a sensitisation pattern similar to that of other industrial allergens, necessitating further research in the field of occupational allergology.

The association between atopic dermatitis and ophthalmological complications is explored in a study by Rønnstad et al.,⁽²⁴⁾ which demonstrates that patients with atopic dermatitis are at a higher risk of developing ophthalmological disorders. This finding is corroborated by the present study, which highlights an increase in cases of atopic keratoconjunctivitis and exacerbations of allergic conjunctivitis among patients with concomitant atopy. Food allergy and the multifactorial approach to its management were examined by Sindher et al.,⁽²⁵⁾ who describe food allergy as a complex process involving genetic, environmental, and immunological interactions. Their findings reinforce the importance of a comprehensive treatment approach, including immunotherapy and personalised dietary recommendations. Das et al.⁽²⁶⁾ established a link between air pollution and allergic eye diseases in children and adolescents. The findings indicate a similar mechanism by which pollutants affect the conjunctiva and exacerbate chronic inflammation, highlighting the importance of environmental factors in the development of allergic eye diseases. Furthermore, the observed seasonal variation in symptoms supports the conclusions of this study. Fukuda et al.⁽²⁷⁾ complemented the present findings by providing a deeper insight into contemporary therapeutic approaches for ocular allergies. Their conclusions confirm the central role of cytokines in the pathological process, particularly in relation to the impact of chemical pollutants. The findings of Fukuda et al. emphasise the need for further research to assess long-term risks and optimise treatment strategies.

The results of this study underscore the importance of cross-reactivity between aeroallergens and food allergens, aligning with the conclusions of Zhao et al.⁽²⁸⁾ These authors suggest that immunotherapy may play a crucial role in reducing cross-reactivity between dust mite allergens and other aeroallergens. However, the effectiveness of this approach remains variable, depending on individual patient characteristics, necessitating further research to optimise immunotherapy protocols.

A meta-analysis conducted by Galor et al.⁽²⁹⁾ emphasised that ocular symptoms such as itching and dryness may have both allergic and non-allergic origins, thereby complicating differential diagnosis. In this context, the findings confirm that allergic mechanisms represent only one of many potential causes of ophthalmological complaints, highlighting the importance of a multifactorial approach to treatment. A meta-analysis conducted by de Groot et al.⁽³⁰⁾ examined sensitisation to 2-hydroxyethyl methacrylate (HEMA) as a factor in the development of contact allergic dermatitis, which is particularly relevant for assessing the risks of occupational sensitisation. Given the widespread use of HEMA in dentistry and cosmetology, there is a need to improve preventive measures and enhance early diagnostic methods for contact allergy to this compound. Villa et al.⁽³¹⁾ analysed the molecular characteristics of sesame allergens, underlining their relevance in assessing cross-reactivity. The findings corroborate the importance of such research in refining the diagnosis of food allergies, as many patients exhibit sensitisation to multiple food products, complicating the identification of the primary allergen. Moreover, the study explored the impact of thermal and technological food processing on allergenicity. Costa et al.⁽³²⁾ focused on allergies to Rosaceae family products, highlighting their clinical significance. As this botanical family includes widely consumed fruits such as apples, peaches, and cherries, some of which were examined in the present study, greater attention should be devoted to diagnostic approaches that identify hidden allergens in food products.

Barber et al.⁽³³⁾ underscored the significance of molecular allergology in advancing the diagnosis and treatment of allergic diseases. The findings further support the importance of this approach in individualising allergy diagnostics. The study by Wolffsohn et al.⁽³⁴⁾ proposed an alternative method for managing ocular allergic reactions, specifically using contact lenses to mitigate allergen exposure. This approach contrasts with conventional treatments centred on pharmacological therapy, highlighting the potential role of a mechanical barrier in preventing exacerbations. Gomes et al.⁽³⁵⁾ established that controlled environments with elevated exposure to triggers can aggravate allergic conjunctivitis symptoms in patients with concurrent dry eye syndrome. Both studies affirm the necessity of a comprehensive approach to diagnosing ophthalmological allergic manifestations. However, Gomes et al. particularly stressed the influence of external factors. The findings of Scheman et al.⁽³⁶⁾ on contact allergy reinforce the importance of identifying sensitisation threshold levels to prevent allergic reactions. This aligns with the conclusions of de Groot et al.⁽³⁰⁾ regarding occupational allergens, particularly methacrylates, although the latter focuses on a specific chemical agent, whereas the former study encompasses a broader spectrum of potential allergens.

Katelaris⁽³⁷⁾ analysed the specificity of ophthalmic allergic reactions in the Asia-Pacific region and identified an increased prevalence of certain types of allergic eye conditions in relation to climatic factors and air pollution levels. This complements the findings of Das and Basu⁽²⁶⁾, who also established a significant impact of pollution on allergic eye manifestations, although their study focused on the paediatric population. Geraldini et al.⁽³⁸⁾ investigated the epidemiology of ocular allergy among adolescents and associated comorbidities. Their findings suggest that atopic dermatitis, asthma, and rhinoconjunctivitis frequently co-occur in these patients, which supports systemic nature of allergic diseases, as evidenced by the analysed data. Furthermore, the study by Beutner et al.⁽³⁹⁾ examined changes in sensitisation to common inhalant allergens in Germany from 2001 to 2021. Their results demonstrate a substantial increase in sensitisation levels, which may be attributed to urbanisation and environmental changes. These findings partially correlate with the present study, further confirming the role of ecological factors in the rising incidence of sensitisation.

The study by Fauquert et al.⁽⁴⁰⁾ provided detailed recommendations regarding the conjunctival provocation test, which is a valuable tool for diagnosing allergic conjunctivitis. Their findings support the necessity of standardising testing procedures and considering individual patient sensitisation. Rasmussen et al.,⁽⁴¹⁾ in their meta-analysis, determined the prevalence of allergic sensitisation in patients with vernal keratoconjunctivitis, reporting a high frequency of polysensitisation. This aligns with the present study, highlighting the importance of accounting for multiple allergens in the diagnosis and management of patients with severe forms of allergic conjunctivitis.

A review of the existing literature offers a deeper understanding of the immune mechanisms underlying allergic reactions affecting the eyes and the influence of various allergens on the development of such conditions. Notably, the study by Jacquet⁽⁴²⁾ emphasised the role of allergens such as dust mites in triggering allergic reactions through immune system activation, supporting the conclusion that aeroallergens are contributors to allergic conjunctivitis. The high level of sensitisation to dust mites reported by Almaliotis et al.⁽⁴³⁾ correlates with the analysed data on the primary allergens responsible for allergic conjunctivitis symptoms, underscoring the importance of dust as a trigger in patients with chronic allergic conjunctivitis. The findings of Shaker et al.⁽⁴⁴⁾ further support the relevance of seasonal fluctuations in allergen levels, which may contribute to cross-reactive allergic responses. Their study reinforces the need for diagnostic and predictive approaches that account for seasonal pollen activity. This, in turn, allows for the anticipation of increased sensitivity to food allergens, particularly during peak pollen seasons, and facilitates appropriate adjustments to treatment strategies.

Zeindl et al.⁽⁴⁵⁾ examined the structural characteristics of food allergens, employing nuclear magnetic resonance spectroscopy to elucidate the mechanisms underlying cross-reactivity between pollen and food allergens, which may induce severe ophthalmic symptoms. These findings align with the established similarity between Bet v 1 protein in birch pollen and certain food components, which can trigger cross-allergic reactions. The expanded approach discussed by Aydin et al.,⁽⁴⁶⁾ which incorporated proteomic analysis of tear fluid, represents a promising avenue for the diagnosis of ophthalmic allergies, as alterations in tear composition may facilitate the precise identification of allergens responsible for inflammation. This underscores the importance of investigating not only classical IgE biomarkers but also other molecular participants in allergic processes. Furthermore, Chigbu et al.⁽⁴⁷⁾ highlighted the importance of understanding the immunological mechanisms underlying allergic eye diseases, particularly the activation of T-lymphocytes and cytokine release. These findings support previous conclusions regarding the critical involvement of cytokines in chronic forms of allergic conjunctivitis, which is essential for the development of novel therapeutic approaches. Similarly, Zemba et al.⁽⁴⁸⁾ examined biomarkers of ocular allergy and dry eye syndrome, emphasising the correlation between specific protein levels in tear fluid and the severity of clinical symptoms. Their results reinforce the relevance of biomarker analysis in advancing personalised treatment strategies, which is consistent with existing evidence regarding the substantial impact of inflammatory processes on symptom severity.

A meta-analysis conducted by Lo et al.⁽⁴⁹⁾ explored the relationship between keratoconus and risk factors such as eye rubbing, atopy, and other allergic conditions. Their findings underscore the comorbidity between allergic pathologies and structural alterations in the cornea, further demonstrating that chronic ocular irritation may exacerbate clinical manifestations, a conclusion that aligns with their results. The study by Meng et al.,⁽⁵⁰⁾ which investigated neuropeptide interactions in the development of allergic rhinoconjunctivitis, rhinitis, and conjunctivitis, corroborates prior findings on the chronic effects of pollutants, which may activate analogous inflammatory mechanisms. Their study highlighted the pivotal role of interactions between sensory nerves and immune responses. Chong-Neto et al.⁽⁵¹⁾ analysed the manifestations of ocular allergy in children and adolescents. Their data indicate that the paediatric population exhibits a higher prevalence of severe forms of allergic conjunctivopathy, underscoring the importance of early diagnosis and prevention.⁽⁵²⁾ This study identified a predisposition to exacerbated allergic reactions in certain patient groups, consistent with their conclusions.

The findings confirm the importance of a comprehensive approach to the diagnosis and treatment of ophthalmic allergic manifestations, which considers not only classical allergens but also their interactions, seasonality, and cross-reactivity. They also reflect global trends in research on allergic eye diseases, contributing to the development of new therapeutic strategies. Future research areas include interactions between different classes of allergens, particularly pollen, food, and chemical allergens, to enhance the understanding of cross-allergy mechanisms. Moreover, emphasis should be placed on the development of novel diagnostic methods, such as tear fluid analysis and other biomarkers, to enable the precise identification of specific allergens and the assessment of treatment efficacy.