Seasonal Allergic Conjunctivitis (SAC)

What You Need to Know

Seasonal allergic conjunctivitis (SAC) is a very common eye condition that happens when your eyes react to allergens in the air during specific seasons, most often in the spring and summer. Think of it as the eye version of hay fever. It’s an immune hypersensitivity disorder, meaning your body’s defense system overreacts to harmless substances. SAC is the most frequent cause of eye allergies. For medical advice or diagnosis, consult a professional.

What Causes SAC?

SAC is primarily triggered by outdoor airborne allergens that are more common during certain times of the year. The main culprits are often pollen from trees, grasses, and weeds. When these tiny particles land on the surface of your eye, in people who are allergic, it sets off a chain reaction involving your immune system.

This reaction is often what’s called an immunoglobulin E (IgE)-mediated hypersensitivity reaction. This means that your body produces specific IgE antibodies that recognize the pollen. When you’re exposed to the same pollen again, these antibodies trigger the release of inflammatory substances, like histamine, from cells in your eye called mast cells.

What are the Symptoms of SAC?

The release of these inflammatory substances leads to various uncomfortable symptoms, which are usually bilateral, meaning they affect both eyes. The most common symptoms include:

• Seasonal Allergic Conjunctivitis (SAC)
• Redness.
• Excessive tearing.
• Foreign body sensation.
• Sensitivity to light (photophobia).
• Thick, stringy, mucous discharge.
• Blurred vision.

How Does SAC Affect You?

While SAC is usually not a serious condition that causes permanent vision loss, it can significantly impact your quality of life. The persistent itching, redness, and tearing can be very bothersome and can interfere with daily activities. It can also lead to decreased productivity at work or school.

SAC and Other Allergies

SAC is often associated with other allergic conditions, particularly allergic rhinitis (hay fever). Many people who experience seasonal nasal allergies also suffer from SAC. In some cases, it can also occur with asthma.

What Can You Do About SAC?

While it’s always best to consult an eye care professional for a proper diagnosis and personalized advice, here are some general approaches often recommended for managing SAC:

• Avoid Allergens: The first step is to try and limit your exposure to the pollen that triggers your symptom. This might include staying indoors on high pollen days, keeping windows closed, and using air purifiers.
• Lubricating Eye Drops (Artificial Tears): These can help to wash away allergens from the eye surface and provide some relief from dryness and irritation.
• Antihistamine Eye Drops: These medications can help to block the action of histamine, the main chemical responsible for the itching and other allergy symptoms.

How Common is SAC?

SAC is a very prevalent condition, affecting a significant portion of the population worldwide. The exact numbers can vary depending on the region and study, but it’s clear that many people experience this type of eye allergy. For example, studies have shown high prevalence rates in countries like Japan.

Complications caused by SAC

• AC can lead to tear film disruption.
• The condition can cause damage to the ocular surface.
• AC is recognized as a key risk factor for inducing dry eye disease (DED).
• In severe cases, papillary hypertrophy of the palpebral conjunctiva may occur.
• Some individuals with AC may develop corneal infections, which can jeopardize vision.
• Occasionally, AC can result in permanent vision loss, especially in severe cases.
• Eye rubbing due to ocular itching associated with AC can lead to corneal ectasia, including keratoconus, which in turn can cause acute corneal hydrops, corneal perforation, corneal scarring, and further vision loss.
• For individuals with pre-existing dry eye disease, AC can exacerbate the symptoms of dry eye.
• Allergic conjunctivitis can potentially lead to limbal stem cell damage.
• Chronic use of topical vasoconstrictors for AC can result in conjunctivitis medicamentosa.

References

1. Alsudais [Author]. Alsudais-2024-The Efficacy and Safety of Dexam.pdf [Title]. 2024.
2. Bashir M, Alghamdi TA, Alghamdi MAA, Aloleeit SK, AlHajji Z, Alsultan ES, et al. Evaluation of AC prevalence and attitude toward prevention and control in the Kingdom of Saudi Arabia. Cureus [Journal]. 2024 Apr;16(4):e57711. doi: 10.7759/cureus.57711.
3. Boghdady WA, Khairy MA, Ali AG, El Shahawy AA, Abdelaziz EA, El Shahawy AA, et al. Correlation between forkhead box P3 (rs3761548) gene polymorphism and serum interleukin13 as biomarkers of severity in Egyptian allergic conjunctivitis: a retrospective study. Front Allergy [Journal]. 2024 Sep 25;5:1437600. doi: 10.3389/falgy.2024.1437600.
4. Cao X, Xu Z, Zhang B, Li Q, Jiang Z, Yuan X. Metabolic Biomarkers Mediate Allergic.pdf [Title]. 2025.
5. Chen [Author]. Chen-2025-From Ocular Surface to Intraocular I.pdf [Title]. 2025.
6. Chigbu DI, Karbach NJ, Abu SL, Hehar NK. Cytokines in Allergic Conjunctivitis: Unraveling Their Pathophysiological Roles. Life [Journal]. 2024 Mar;14(3):350. doi: 10.3390/life14030350.
7. El-Shahed [Author], Abdelrehim RT, Fouda NH, Hegazy DA, Habib BA. Polymeric Mixed Micelle-Loaded.pdf [Title]. 2024.
8. Elhabal SF, El-Nabarawi MA, Elrefai MFM, Teaima MH, Shoela MS, Khamis GM, et al. Nano‑spanlastics‑loaded dissolving microneedle patches for ketotifen fumarate: advanced strategies for allergic conjunctivitis treatment and molecular insights. Drug Deliv Transl Res [Journal]. 2025 Feb;15(2):1107-1124. doi: 10.1007/s13346-025-01796-x.
9. Fu X, Xu P, Lu D. Comparative assessment of alcaftadine and olopatadine for the treatment of allergic conjunctivitis: a meta-analysis. Adv Dermatol Allergol [Journal]. 2024 Dec;6:558-566. doi: 10.5114/ada.2024.145045.
10. Fujio K, Sung J, Hirosawa K, Yamaguchi M, Toshida H, Inagaki K, et al. Effect of antihistamine-releasing contact lens on ocular itching and conjunctival redness in patients with seasonal allergic conjunctivitis: A prospective, randomized, double-masked, placebo-controlled trial. Heliyon [Journal]. 2024 Nov;10(18):e33385. doi: 10.1016/j.heliyon.2024.e33385.
11. Fujishima H, Shoji J. Safety and efficacy of a novel epinastine 0.5% ophthalmic cream for the long-term prevention of allergic conjunctivitis: A phase 3, multicenter, randomized, double-masked, vehicle-controlled study. Adv Ther [Journal]. 2024 Dec;41(12):4811-4826. doi: 10.1007/s12325-024-03032-4.
12. Kenyon KR, Torkildsen G, чистосердов A, чистосердова N, чистосердов E, чистосердов С, et al. A Randomized, Multicenter Phase 3 Study Evaluating the Efficacy and Safety of a Novel Dexamethasone Intracanalicular Insert for the Treatment of Seasonal Allergic Conjunctivitis. Clin Ophthalmol [Journal]. 2024;18:3489-3501. doi: 10.2147/OPTH.S424601.
13. Leonardi A, Quintieri L, Presa IJ, Lloves JM, Montero J, Benítez-Del-Castillo JM, et al. Allergic Conjunctivitis Management: Update on Ophthalmic Solutions. Curr Allergy Asthma Rep [Journal]. 2024 Oct;24(10):347-360. doi: 10.1007/s11882-024-01116-9.
14. Liu D, Gui S, Wang X, Wang Q, Qiao J, Tao F, et al. Long-term effects of air pollution on daily outpatient visits for allergic conjunctivitis from 2013 to 2020: a time-series study in Urumqi, China. Front Public Health [Journal]. 2024 Oct 25;12:1325956. doi: 10.3389/fpubh.2024.1325956.