Retinoblastoma may occur in one or both eyes. Retinoblastoma has few, if any, symptoms at first. It may be noticed if a pupil appears white when light is shone into the eye, sometimes with flash photography. Eyes may appear to be looking in different directions. Treatments include chemotherapy, radiation and laser therapy. A research article is a primary source which reports the methods and results of an original study done by the authors. It is a methods section, where authors describe how they collected and analysed data where statistical analyses are included.