EP Optical Center 1

11/05/2026

Why Do Onions Make Your Eyes Cry? The Science Behind Onion Tears

Have you ever wondered why cutting an onion can make your eyes water even when you are not upset? The answer lies in a fascinating chemical defence mechanism inside the onion. When an onion is sliced, its damaged cells release substances that react to form a volatile chemical irritant. This substance travels through the air and reaches the surface of your eyes.

Your eyes respond by activating a protective reflex that stimulates tear production. These reflex tears help dilute and wash away the irritating substance, protecting the delicate ocular surface. In other words, your eyes are not crying because of emotion — they are trying to defend themselves.

1. What happens when you cut an onion?

• Inside an intact onion, different chemical substances are stored separately within its cells.
• Cutting or crushing the onion damages these cells and allows their contents to mix.
• An enzyme called alliinase acts on sulfur-containing compounds, including 1-propenyl cysteine sulfoxide.
• This reaction produces an unstable intermediate that is converted into a volatile chemical irritant called syn-propanethial-S-oxide.
• This compound is commonly known as the onion lachrymatory factor.
• Because it is volatile, it can travel through the air and reach your eyes.

2. How does the onion chemical reach your eyes?

• The volatile lachrymatory factor moves through the surrounding air.
• It reaches the exposed ocular surface and interacts with the tear film.
• The chemical irritates sensory nerve endings in the cornea and conjunctiva.
• These sensory signals are transmitted through branches of the trigeminal nerve.
• The nervous system interprets this irritation as a potential threat to the ocular surface.

3. Why do your eyes produce tears?

The eye has a protective reflex mechanism designed to remove irritating substances from its surface.

• Sensory nerve endings in the cornea and conjunctiva detect the chemical irritation.
• Signals travel through the trigeminal sensory pathway to the brainstem.
• Reflex pathways activate parasympathetic stimulation of the lacrimal gland.
• The lacrimal gland produces additional watery tears.
• These tears spread across the ocular surface and help dilute and wash away the irritant.

This is known as reflex lacrimation. It is the same general protective response that can occur when smoke, dust or other irritating substances enter the eye.

4. Why does the cornea react so strongly?

• The cornea is one of the most densely innervated tissues in the human body.
• Its sensory nerve endings provide exceptional sensitivity to potential threats.
• Even relatively small amounts of an irritating substance can activate protective reflexes.
• Increased tear production helps maintain the ocular surface and remove unwanted substances.
• This sensitivity is essential for protecting the transparent cornea and maintaining clear vision.

5. Why does one person cry more than another?

• Individual sensitivity to chemical irritation varies.
• The amount of lachrymatory factor released depends on the onion and how it is cut.
• Cutting technique and the condition of the knife influence cell damage.
• Poor ventilation allows more irritant to accumulate around the face.
• Existing ocular surface sensitivity may influence how uncomfortable the irritation feels.
• Tear production and individual reflex responses also differ.

6. How can you reduce onion-induced tearing?

• Use a sharp knife to reduce unnecessary crushing of onion cells.
• Chill the onion before cutting; lower temperatures can reduce the release and volatility of irritating compounds.
• Cut onions near an exhaust fan or in a well-ventilated area.
• Keep your face slightly farther away from the cutting surface.
• Use protective kitchen goggles to reduce exposure of the ocular surface.
• Avoid rubbing your eyes after handling freshly cut onions.

7. Is onion-induced tearing harmful?

• For most people, onion-induced tearing is temporary and harmless.
• The irritation usually settles after exposure to the chemical decreases.
• Reflex tears help remove the irritant from the ocular surface.
• Persistent pain, marked redness, photophobia or blurred vision after exposure should not automatically be attributed to onion irritation.
• If symptoms persist or vision is affected, an eye examination may be necessary.

8. Key clinical takeaway

Onions make your eyes water because cutting them releases a volatile chemical called syn-propanethial-S-oxide.

This chemical irritates sensory nerve endings in the cornea and conjunctiva, activating a trigeminal-mediated protective reflex that stimulates lacrimal tear production.

Your eyes are essentially performing a natural cleaning response — producing extra tears to dilute and wash away the irritant.

The next time you cut an onion, remember: those tears are not emotional. They are your ocular defence system at work!

11/04/2026

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11/04/2026

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10/16/2026

WHY ARE YOUR EYES WATERING WHEN THEY ARE DRY? THE SCIENCE OF REFLEX TEARING

Watery eyes are commonly associated with excessive tear production, but they can also be a sign of dry eye disease. Although this may appear contradictory, the explanation lies in the difference between tear quantity and tear film quality. Eyes can produce plenty of tears while still failing to maintain a stable, protective tear film over the ocular surface.

When the tear film becomes unstable, parts of the corneal surface may become exposed or inadequately lubricated between blinks. This can stimulate sensory nerves and trigger reflex lacrimation, producing a sudden overflow of watery tears. Understanding this mechanism helps explain why some patients with dry eye disease complain more about watering than dryness.

1. THE TEAR FILM: MORE THAN JUST WATER

The tear film maintains a smooth optical surface, lubricates the eyelids, protects the corneal epithelium, and supports ocular surface health.

Its components are commonly taught as three layers:
• Lipid layer: Produced primarily by the meibomian glands; helps reduce evaporation and stabilizes the tear film.
• Aqueous component: Supplied mainly by the lacrimal glands; provides hydration and carries electrolytes, proteins, and other protective substances.
• Mucin component: Helps the tear film spread and interact with the ocular surface.

Modern models often describe the tear film as an outer lipid layer over a largely integrated mucoaqueous phase rather than three completely separate layers.

A healthy tear film must not only contain sufficient fluid but also spread evenly and remain stable between blinks. If its composition or distribution is abnormal, the ocular surface may become dry despite apparently abundant tears.

2. WHY DRY EYES PRODUCE EXCESSIVE TEARING

The mechanism involves a compensatory reflex.

Step 1 — Tear film instability
The tear film becomes unstable because of excessive evaporation, inadequate tear production, meibomian gland dysfunction, or other ocular surface abnormalities.

Step 2 — Localized surface desiccation
The tear film thins or breaks up between blinks, leaving portions of the ocular surface inadequately protected.

Step 3 — Sensory nerve stimulation
Ocular surface sensory pathways respond to irritation and desiccating stress. Patients may experience burning, stinging, grittiness, foreign-body sensation, or fluctuating vision.

Step 4 — Reflex lacrimation
Neural signals stimulate the lacrimal functional unit, increasing aqueous tear secretion in an attempt to protect the ocular surface.

Step 5 — Tear overflow
The sudden increase in watery tears may exceed the capacity of the normal drainage system, causing tears to spill over the eyelid margin.

The key point is that reflex tearing is a protective response. It may temporarily increase the volume of tears without correcting the underlying tear film instability.

3. COMMON CAUSES OF DRY EYE WITH WATERY EYES

A. EVAPORATIVE DRY EYE
Meibomian gland dysfunction is a major contributor to evaporative dry eye. When the glands produce insufficient or abnormal meibum, the lipid layer may not adequately limit evaporation.

Typical symptoms:
• Watering that fluctuates throughout the day
• Burning or gritty sensations
• Discomfort during prolonged screen use
• Symptoms in air-conditioned, windy, or dry environments

B. AQUEOUS-DEFICIENT DRY EYE
The lacrimal glands produce insufficient aqueous tears to maintain normal ocular surface hydration.

Possible contributors include aging, certain medications, and systemic conditions such as Sjögren syndrome. Reflex tearing may still occur, so occasional watery overflow does not exclude reduced basal tear production.

C. BLEPHARITIS AND OCULAR SURFACE INFLAMMATION
Inflammation along the eyelid margins can disrupt the tear film, irritate the ocular surface, and contribute to reflex tearing. Associated meibomian gland dysfunction may further increase evaporation.

D. ENVIRONMENTAL AND BEHAVIORAL FACTORS
Wind, smoke, air conditioning, low humidity, and prolonged screen use may aggravate ocular surface dryness. Reduced or incomplete blinking during concentrated visual tasks can increase tear film instability.

4. HOW OPTOMETRISTS INVESTIGATE WATERY EYES

Excessive tearing should not automatically be diagnosed as dry eye. A structured assessment helps distinguish reflex tearing from impaired tear drainage and other ocular conditions.

Clinical assessment may include:
• History: Onset, duration, laterality, environmental triggers, medication use, and associated discomfort.
• Visual acuity: Assess for associated visual impairment.
• Slit-lamp biomicroscopy: Examine the cornea, conjunctiva, tear meniscus, and eyelid margins.
• Tear film stability: Assess tear breakup time or non-invasive tear breakup time.
• Ocular surface staining: Fluorescein and, when appropriate, lissamine green can help identify epithelial or conjunctival abnormalities.
• Meibomian gland assessment: Evaluate gland or***ce obstruction, secretion quality, and expressibility.
• Tear production testing: Schirmer testing may be appropriate in selected patients.
• Lacrimal drainage assessment: Consider punctal abnormalities or drainage obstruction when the clinical pattern suggests epiphora.

The diagnosis should be based on the combination of symptoms, examination findings, and appropriate tests rather than watering alone.

5. DRY EYE VS OTHER CAUSES OF EPIPHORA

Not all watery eyes are caused by dry eye disease.

Other important causes include:
• Nasolacrimal drainage obstruction
• Allergic conjunctivitis
• Blepharitis
• Corneal foreign bodies or abrasions
• Eyelid malposition, including ectropion
• Trichiasis or other sources of ocular surface irritation
• Infection and other inflammatory eye conditions

Bilateral fluctuating watering accompanied by burning or grittiness may support ocular surface disease. Persistent unilateral watering, recurrent discharge, or symptoms associated with lacrimal sac swelling should prompt assessment for drainage or other local pathology.

6. MANAGEMENT: TREAT THE UNDERLYING CAUSE

Treatment depends on the type and severity of dry eye and whether another cause of epiphora is present.

Practical measures:
• Use appropriate artificial tears; preservative-free formulations may be preferable when drops are needed frequently or the ocular surface is sensitive.
• Apply warm compresses and perform appropriate eyelid hygiene when meibomian gland dysfunction is present.
• Take regular breaks during prolonged screen use and blink fully and frequently.
• Reduce direct exposure to fans, air conditioning, smoke, and wind.
• Consider environmental humidification when the air is dry.
• Review potentially contributory medications with the prescribing clinician rather than stopping them independently.
• Seek professional assessment if symptoms persist, recur frequently, or fail to respond to basic measures.

Moderate or severe disease may require prescription anti-inflammatory therapy, other targeted treatments, or management of an underlying eyelid or lacrimal drainage disorder. These interventions should be selected after appropriate clinical evaluation.

7. WHEN SHOULD WATERY EYES BE EXAMINED URGENTLY?

Prompt ophthalmic assessment is important when watering is accompanied by:
• Eye pain or marked photophobia
• New or significant reduction in vision
• Pronounced redness, particularly in one eye
• Corneal opacity or a suspected foreign body
• Chemical exposure or eye trauma
• Contact lens use accompanied by pain, redness, or visual changes

Persistent unilateral tearing, recurrent discharge, or swelling near the inner corner of the eye also warrants medical assessment.

8. CLINICAL PEARLS FOR OPTOMETRISTS

• Tear volume and tear film stability are different clinical parameters.
• Reflex tearing can coexist with an unstable or deficient tear film.
• Meibomian gland dysfunction should be considered in patients with evaporative symptoms.
• A normal or high tear meniscus does not independently exclude dry eye disease.
• Assess tear film quality, ocular surface integrity, eyelid function, and lacrimal drainage before determining the cause of epiphora.
• Treatment should target the underlying mechanism rather than simply attempting to suppress watering.

CONCLUSION

Your eyes can water excessively and still be dry. When tear film instability irritates the ocular surface, reflex lacrimation may increase tear production, but the additional fluid does not necessarily restore a stable, protective tear film. Recognizing this relationship helps clinicians distinguish dry eye-related reflex tearing from lacrimal drainage disorders and other causes of epiphora.

REFERENCES

1. Tear Film & Ocular Surface Society (TFOS). TFOS DEWS II: Definition and Classification.
https://www.tfosdewsreport.org/report-definition_and_classification/48_36/en/
2. National Eye Institute. How Tears Work.
https://www.nei.nih.gov/eye-health-information/healthy-vision/how-eyes-work/how-tears-work
3. National Eye Institute. Dry Eye.
https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/dry-eye
4. TFOS DEWS II. Diagnostic Methodology.
https://www.tfosdewsreport.org/report-diagnostic_methodology/131_36/en/
5. TFOS DEWS II. Management and Therapy.
https://www.tfosdewsreport.org/report-management_and_therapy/147_36/en/

10/14/2026

CONTACT LENSES + WATER: A HIDDEN RISK TO YOUR EYES

Showering, swimming, or using a hot tub while wearing contact lenses may seem harmless, but water exposure can increase the risk of serious corneal infections. One particularly concerning infection is Acanthamoeba keratitis, a rare but potentially sight-threatening condition that can be difficult to treat. Simple contact lens hygiene habits can help reduce this risk.

1. WATER IS NOT SAFE FOR CONTACT LENSES
Tap water, bottled water, swimming pools, lakes, and hot tubs may contain microorganisms that can contaminate contact lenses. Contact lenses should not be exposed to water, including during showering or swimming.

2. MEET ACANTHAMOEBA
Acanthamoeba is a microscopic, free-living amoeba found in water, soil, and dust. If it infects the cornea, it can cause Acanthamoeba keratitis, a serious infection associated particularly with contact lens wear and improper lens hygiene.

3. EARLY SYMPTOMS CAN BE MISLEADING
Possible symptoms include:
Eye pain or redness
Sensitivity to light
Excessive tearing
Foreign-body sensation
Blurred or reduced vision

These symptoms can resemble other eye infections, so clinical assessment is important.

4. FOLLOW THESE CONTACT LENS SAFETY RULES
Remove contact lenses before showering, swimming, or entering a hot tub.
Wash your hands and dry them completely before handling lenses.
Use only the recommended contact lens disinfecting solution.
Never rinse or store lenses or their case in water.
Never top off old solution with fresh solution.
Clean and air-dry the lens case as directed, and replace it according to professional guidance and product instructions.

5. WHAT IF YOUR CONTACT LENSES GET WET?
Remove them as soon as possible. Discard daily disposable lenses. For reusable lenses, follow the manufacturer’s instructions and complete the recommended cleaning and disinfection process before wearing them again. If you develop pain, redness, light sensitivity, or blurred vision, do not reinsert the lenses and seek prompt eye-care assessment.

KEY TAKEAWAY
Contact lenses and water are a risky combination. Keeping lenses away from water and following proper hygiene practices can help protect your cornea and preserve your vision.

Do you remove your contact lenses before sleeping?

SOURCES AND REFERENCES

1. Centers for Disease Control and Prevention (CDC) — Acanthamoeba Keratitis: https://www.cdc.gov/acanthamoeba/about/about-acanthamoeba-keratitis.html
2. Centers for Disease Control and Prevention (CDC) — Preventing Eye Infections When Wearing Contacts: https://www.cdc.gov/contact-lenses/prevention/index.html
3. U.S. Food and Drug Administration (FDA) — Contact Lens Care: https://www.fda.gov/medical-devices/contact-lenses/contact-lens-care
4. American Optometric Association (AOA) — Contact Lens Care: https://www.aoa.org/healthy-eyes/vision-and-vision-correction/contact-lens-care

10/09/2026

Why Do You Suddenly See Flashes & Floaters?

Have you ever noticed tiny spots, cobwebs, threads, or flashes of light suddenly appearing in your vision? These symptoms can be alarming, especially when they occur without warning. In many cases, they are related to natural age-related changes occurring inside the vitreous gel that fills the eye.

One of the most common causes is Posterior Vitreous Detachment (PVD), a condition in which the vitreous gel gradually separates from the retina as it becomes more liquefied with age. Although PVD is usually harmless, new flashes and floaters should never be ignored because they can occasionally signal a retinal tear or retinal detachment.

1. What Are Floaters?

• Floaters appear as small spots, dots, cobwebs, threads, rings, or drifting shadows in your field of vision.
• They are usually caused by tiny clumps or condensations within the vitreous gel.
• These structures cast shadows on the retina, making them visible to the patient.
• Floaters are often easier to notice against a bright sky or plain background.

2. What Are Flashes?

• Flashes are brief streaks or sparks of light seen without an external light source.
• They occur when the vitreous pulls on the retina.
• This mechanical traction stimulates retinal cells, creating the sensation of light.
• Flashes are often more noticeable in dim environments or at night.

3. What Is Posterior Vitreous Detachment (PVD)?

• The vitreous is a transparent gel that fills the center of the eye.
• With aging, the vitreous becomes more liquid and shrinks.
• Eventually, it may separate from the retina.
• This process is called Posterior Vitreous Detachment (PVD).
• PVD is a common age-related event and often occurs without permanent vision loss.

4. Why Do Floaters Increase During PVD?

• As the vitreous separates, collagen fibers can aggregate into visible strands.
• A ring-shaped floater known as a Weiss ring may appear when tissue detaches near the optic nerve.
• Patients may suddenly notice more floaters than usual during this process.

5. When Are Flashes and Floaters Dangerous?

Seek urgent ophthalmic evaluation if you experience:

• A sudden shower of new floaters.
• A dramatic increase in flashes of light.
• A dark curtain or shadow moving across your vision.
• Loss of peripheral vision.
• Sudden decrease in visual acuity.

6. Why Is Immediate Examination Important?

• Vitreoretinal traction can sometimes create a retinal tear.
• A retinal tear may progress to retinal detachment.
• Retinal detachment is a vision-threatening emergency.
• Early diagnosis and treatment can significantly improve visual outcomes.

7. Who Is More Likely to Develop PVD?

• Adults over 50 years of age.
• Individuals with myopia (nearsightedness).
• Patients who have undergone cataract surgery.
• Individuals with previous ocular trauma.
• Patients with certain retinal conditions.

8. What Should You Do If Symptoms Occur?

• Arrange a comprehensive dilated retinal examination promptly.
• Do not assume new flashes and floaters are harmless.
• Follow your eye-care professional’s recommendations for follow-up.
• Return immediately if symptoms worsen or new visual field defects develop.

Key Takeaway

Most flashes and floaters are caused by normal vitreous aging and Posterior Vitreous Detachment. However, because the same symptoms can also indicate a retinal tear or retinal detachment, any sudden onset of flashes, a large increase in floaters, or the appearance of a curtain-like shadow requires urgent ophthalmic evaluation. Early detection can help protect vision and prevent serious complications.

Sources

• American Academy of Ophthalmology (AAO) – EyeWiki: Posterior Vitreous Detachment
• American Academy of Ophthalmology – What Are Floaters and Flashes?
• American Academy of Ophthalmology – What Is a Posterior Vitreous Detachment?
• National Eye Institute (NEI) – Retinal Detachment
• AAO Preferred Practice Pattern: Posterior Vitreous Detachment, Retinal Breaks, and Lattice Degeneration

10/05/2026

Eye Injury Prevention Month: Sports Ocular Safety & Impact Prevention

Eye injuries can occur in a fraction of a second during sports and recreational activities, yet many are entirely preventable. Whether playing tennis, cricket, baseball, hockey, basketball, or participating in outdoor adventure sports, protecting the eyes should be considered just as important as protecting the head, teeth, or joints. Good vision plays a critical role in athletic performance, reaction time, coordination, and overall safety.

Today, October 4, 2026, Eye Injury Prevention Month highlights the importance of sports ocular safety and impact prevention. This observance encourages athletes, parents, coaches, educators, healthcare providers, and eye care professionals to promote protective eyewear and safe sporting practices that help preserve vision and reduce the risk of preventable eye injuries.

1. Why Sports Eye Safety Matters

Vision is one of an athlete’s most valuable assets.
• More than 90% of serious sports-related eye injuries are considered preventable.
• Eye injuries can affect both professional athletes and recreational players.
• Children and adolescents are among the highest-risk groups.
• Some injuries may result in permanent visual impairment.
• Appropriate eye protection significantly reduces injury risk.

2. Common Sports-Related Eye Injuries

Sports trauma can affect nearly every structure of the eye.
• Corneal abrasion.
• Eyelid laceration.
• Hyphema.
• Orbital fracture.
• Retinal tear.
• Retinal detachment.
• Vitreous hemorrhage.
• Traumatic cataract.
• Lens dislocation.
• Globe rupture.

3. Sports Associated with Increased Risk

Certain activities expose participants to greater ocular hazards.
• Tennis.
• Squash.
• Racquetball.
• Cricket.
• Baseball.
• Basketball.
• Hockey.
• Martial arts.
• Paintball.
• Cycling.
• Field sports involving projectiles.
• Recreational outdoor activities.

4. The Role of Protective Sports Eyewear

Modern protective eyewear is designed to combine safety, comfort, and performance.
• Polycarbonate lenses provide excellent impact resistance.
• Sports goggles help shield the eyes from direct trauma.
• Wrap-around designs offer improved peripheral protection.
• Prescription sports eyewear allows clear vision without sacrificing safety.
• Protective eyewear reduces the risk of severe ocular injury.

5. Children, Youth Sports, and Eye Protection

Young athletes often underestimate the risk of eye injuries.
• Introduce protective eyewear early.
• Encourage consistent use during practices and games.
• Replace damaged goggles immediately.
• Ensure proper fitting and comfort.
• Educate parents and coaches about sports eye safety.

6. Warning Signs That Require Immediate Evaluation

Prompt assessment can help prevent permanent vision loss.
• Sudden blurred vision.
• Eye pain.
• Persistent redness.
• Flashes of light.
• New floaters.
• Double vision.
• Visible bleeding.
• Loss of peripheral vision.
• Sudden reduction in visual acuity.
• Eye deformity following trauma.

7. Building a Culture of Prevention

Preventing eye injuries requires awareness and preparation.
• Wear sport-specific protective eyewear.
• Follow safety rules and guidelines.
• Maintain sports equipment properly.
• Promote eye safety education.
• Keep first-aid resources available.
• Seek immediate medical attention after significant eye trauma.
• Schedule regular comprehensive eye examinations.

8. History and Ongoing Impact

Eye Injury Prevention Month was established to increase public awareness of preventable eye injuries occurring during sports, work, home activities, and recreation. Over the years, educational initiatives have emphasized protective eyewear, injury prevention strategies, and timely treatment of ocular trauma. These efforts continue to help reduce avoidable vision loss and encourage safer participation in sports and everyday activities worldwide.

Sources

American Academy of Ophthalmology (AAO):
https://www.aao.org/eye-health/tips-prevention/injuries-sports-eye-safety

Prevent Blindness:
https://preventblindness.org/sports-eye-safety

National Eye Institute (NEI):
https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/keep-your-eyes-healthy

American Optometric Association (AOA):
https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/sports-and-eye-safety

Centers for Disease Control and Prevention (CDC):
https://www.cdc.gov/visionhealth

09/05/2026

Titan Minimal Art is all about lightness, comfort and a design reduced to the essentials. Every detail is carefully engineered to create a frame that feels almost weightless.

What makes the Titan Minimal Art construction so unique?
A No screws and no hinges
B No titanium
C No nose pads
Share your answer in the comments below.

07/24/2026

07/18/2026

Are you experiencing dry, irritated, or watery eyes? You're among millions who face dry eye symptoms daily. Fortunately, your eye doctor can provide simple yet effective solutions for long-term relief.