Tic disorder (e.g., Tourette syndrome or transient tic disorder): This is the most likely diagnosis given the age of the patient and the fact that the eye doctor has ruled out any eye issues. Tics often worsen with stress or anxiety, which could explain why the blinking is worse during the school year.

Anxiety or stress: Excessive blinking can be a manifestation of anxiety or stress in children. The school environment can be a significant source of stress for some children, leading to an increase in blinking.
Habit: Some children develop habits like excessive blinking, which can be exacerbated by stress or boredom, common during the school year.
Allergies: Although the eye doctor has ruled out eye issues, allergies could still cause discomfort leading to blinking, especially if the allergies are not directly related to the eyes (e.g., seasonal allergies affecting the nasal passages or throat).

Neurological disorders (e.g., basal ganglia disorders, dystonia): While less common, certain neurological disorders can present with movement disorders, including excessive blinking. Early diagnosis is crucial for appropriate management.
Drug-induced blinking: Certain medications can cause blinking as a side effect. It's essential to review any medications the child might be taking.

Blepharospasm: A rare neurological disorder characterized by involuntary blinking or spasms of the eyelids. It's less common in children but should be considered if other diagnoses are ruled out.
Tardive dyskinesia: Although rare in children, this condition, often associated with long-term use of neuroleptic drugs, can cause involuntary, repetitive body movements, including blinking.