The most common symptom of retinoblastoma is leukocoria.
Leukocoria results when the pupil reflects a white color rather than the normal black or red color that is seen on a flash photograph.
The pediatrician will often perform a red reflex test to diagnose or confirm leukocoria.
The doctor then examines the eyes with an ophthalmoscope, which shines a bright light into the eyes and allows the doctor to check for leukocoria.
Leukocoria can also be diagnosed by taking a flash Polaroid photograph of a patient who has been in a dark room for three to five minutes.