Dacryocystitis is the infection of the lacrimal sac. The lacrimal sac is present in the inner corner of the eye and is responsible for the drainage of tears into the nasolacrimal duct. Tears produced are essential for lubricating the eye surface and maintaining it free of microorganisms, dust, and dirt. It is common in children and is called congenital dacryocystitis. The infection of the lacrimal sac is caused due to the blockage in the duct, thus giving way for bacteria to accommodate the sac causing infection. The duct gets blocked because of many reasons, and they are,

Nose or eye injury.
Presence of nasal polyps (non-cancerous growth seen along the inner lining of the nasal cavity).
Sinusitis (inflammation of the layers of sinus structures).
Surgery of the nose or sinus.
Cancer.

Dacryocystitis condition presents with symptoms like,

Pain and redness in the corner of the eye.
Swelling in the corner of the eye.
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Pus discharge from the eye.
Fever.

To diagnose the underlying cause, the doctor will ask the patient to undergo computed tomography (CT scan). The first line of treatment for dacryocystitis is the use of antibiotics. In milder cases, oral antibiotics are preferred, and intravenous injections of antibiotics are preferred in severe cases. To ease the swelling, warm compresses will be advised. After the condition subsides completely, a dacryocystorhinostomy procedure is suggested to widen the duct to avoid future infections. Meningitis (inflammation of the layers of the brain) and brain abscess are a few of the complications seen with untreated dacryocystitis.

What Is Blepharitis?

The inflammation of the eyelids is called blepharitis. It will usually involve both the eyes and the lid's edges. Blepharitis is caused by the obstruction of the oil glands at the base of the lashes, causing irritation and redness. It is always associated with other conditions and is one of those which are believed to be the cause.

Common conditions associated with blepharitis conditions are,

Rosacea - It is seen as a red and burning condition of the eye caused by the rosacea condition of the skin.
Dry Eyes - This condition is caused by the inadequate production of tears which is essential to lubricate the surfaces of the eye. A burning sensation is a common sign.
Eyelash Mites - These are tiny bugs found in the eyelashes and are believed to be caused by the rosacea condition.
Seborrheic Dermatitis - A condition of the itchy scalp caused by stress, detergents, chemicals, and soaps.
Allergies due to eye drops, eye makeup, and contact lens solutions.
Clogged oil glands of the eyelids.

Blepharitis condition will present with symptoms like,

Pain and redness of the eye.
Tearing eyes.
Swollen eyelids.
Frequent blinking of the eye.
Blurred vision.
Burning sensation.
The eyes are sensitive to light.
The skin around the eyelids starts to flake.

Microscopic examination and swab (skin) test are the standard diagnostic methods used for assessing blepharitis.

Antibiotics to fight the infection, steroids for inflammation and topical Cyclosporine to ease the overall blepharitis condition are the line of treatment. The underlying conditions should be treated as well.

Pink eye, stye, severe dry eyes, and tearing are the complications of untreated blepharitis.

What Are Pterygium and Pinguecula?

Pinguecula is a yellowish growth in the conjunctival layer of the eye, and the pinguecula can become severe and form a fleshy tissue containing blood vessels called pterygium. Pinguecula is formed by the deposition of protein, calcium, and fat. Both pinguecula and pterygium are believed to be caused by ultraviolet radiation, wind, and dust.

Pinguecula and pterygium will present with symptoms like,

Itchy eyes.
Swelling and redness of the affected site.
Burning sensation.
A feeling of something stuck in the eye.
Blurry vision.

Generally, treatment is not required for pinguecula and pterygium. But in cases where vision is obstructed, treatment is needed.

Lubricating drops will be prescribed to ease the itchy and irritant eye.
Steroidal eye drops will be given to heal the swelling and redness of the eyes if present.
Surgery is needed if the growth of the tissue is increasing. Pterygium will be removed and replaced with healthy tissue to avoid future pterygium growths.

What Is a Stye?

A stye is nearly like acne or a pimple formed due to the blockage of oil glands on the edges of the eyelids. A stye is a reddish bump on the edges of the eyelid.

There are two types of styes: the external styes (present on the outer layer of the eyelids) and the internal styes (present on the inner layer of the eyelids).

It is caused by the bacterial infection of oil glands present near the edges of the lid. The most common symptoms of a stye are,

A red bump on the edges of the lid.
Pain and redness.
Swelling of the lid.
Sensitive to light.
Tearing eye.
A feeling of something present in the eye.

This condition can be treated at home with warm compresses and cleaning the eyelids with eyelid wipes bought from drug stores.

How Can a Foreign Body Cause Pain in the Eyes?

Foreign bodies like eyelashes, metal, glass, sand, and dust may get into the eye and cause pain and irritation. Tears are generally produced as a defense mechanism to wash out the foreign body.

If a foreign body is present, the eye will show signs like,

Pain.
Redness.
Blurred vision.
A feeling of something present in the eye.
Sensitive to light.

In most cases, these foreign bodies can be removed by flushing the eye with clean running water.

Conclusion

Most of the conditions resulting in the pain in the corner of the eye can be treated with warm compresses and eye drops. However, if the condition does not resolve in a few days, consulting an ophthalmologist to treat the disease is a must.