Dry Eye Syndrome: This is a common condition that can cause eyeball pain, especially if the eyes are not producing enough tears or the tears are of poor quality. It's often related to environmental factors, contact lens use, or underlying medical conditions.

Conjunctivitis: Also known as pink eye, this is an inflammation or infection of the outer membrane of the eyeball and the inner eyelid. It can be caused by viruses, bacteria, or allergens and is characterized by redness, itching, and discharge.
Blepharitis: An inflammation of the eyelids that can cause pain, redness, and swelling. It's often associated with a bacterial or demodex mite infestation and can lead to complications like conjunctivitis or keratitis.
Keratitis: An inflammation of the cornea, which can be caused by infection, injury, or underlying conditions like dry eye. Symptoms include pain, redness, and sensitivity to light.
Glaucoma: A group of eye conditions that damage the optic nerve, often due to abnormally high pressure in the eye. It can cause severe eyeball pain, especially at night, along with nausea and vomiting.

Acute Angle-Closure Glaucoma: A medical emergency that requires immediate attention. It's characterized by sudden, severe eyeball pain, redness, nausea, vomiting, and vision loss. If not treated promptly, it can lead to permanent vision loss.
Endophthalmitis: A severe inflammation of the interior of the eye, usually caused by infection. It's a rare but potentially devastating complication of eye surgery, injections, or trauma, and can lead to vision loss if not treated promptly.
Orbital Cellulitis: An infection of the tissues surrounding the eye, which can cause pain, swelling, and vision changes. It's more common in children and can lead to serious complications if not treated aggressively.

Scleritis: A severe inflammation of the sclera (the white part of the eye), which can cause deep, boring pain and tenderness to the touch. It's often associated with underlying autoimmune disorders.
Uveitis: An inflammation of the uvea, the middle layer of the eye, which can cause pain, redness, and sensitivity to light. It can be associated with various systemic diseases or be idiopathic.
Optic Neuritis: An inflammation of the optic nerve, which can cause pain with eye movement and vision loss. It's often associated with multiple sclerosis or other demyelinating diseases.