Conjunctivitis: This is the most common cause of a red eye in children, often due to viral or bacterial infections. The presence of a red spot could be indicative of a localized infection or inflammation.

Corneal Abrasion: A scratch on the cornea can cause a red spot and is a common injury in children, often resulting from accidental trauma or foreign bodies in the eye.
Allergic Conjunctivitis: Seasonal or perennial allergies can cause redness, itching, and the appearance of a red spot in the eye due to allergic reactions.
Blepharitis: Inflammation of the eyelids can lead to redness and the appearance of spots due to meibomian gland dysfunction or anterior blepharitis.

Retinoblastoma: Although rare, this is a critical diagnosis not to miss, as it is a malignant tumor of the retina that can present with a red eye or leukocoria (a white reflex in the pupil).
Endophthalmitis: A severe inflammation of the interior of the eye, usually caused by infection. It is a medical emergency and can present with severe eye pain, redness, and vision loss.
Orbital Cellulitis: An infection of the tissues surrounding the eye, which can cause redness, swelling, and protrusion of the eye. It requires prompt antibiotic treatment to prevent serious complications.

Keratitis: Inflammation of the cornea, which can be caused by infection, injury, or underlying conditions. It can present with a red spot and requires specific treatment to prevent vision loss.
Scleritis: Inflammation of the sclera (the white part of the eye), which can cause severe pain, redness, and tenderness. It is less common in children but can be associated with systemic diseases.
Uveitis: Inflammation of the uvea (the middle layer of the eye), which can cause pain, redness, and sensitivity to light. It is rare in children but can be associated with systemic diseases or infections.