This is a medical question of type : exams and tests 
 How to diagnose Retinoblastoma ? 
 The following tests and procedures may be used:         -   Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patients health habits and past illnesses and treatments will also be taken. The doctor will ask if there is a family history of retinoblastoma.    -  Eye exam with dilated pupil: An exam of the eye in which the pupil is dilated (opened wider) with medicated eye drops to allow the doctor to look through the lens and pupil to the retina. The inside of the eye, including the retina and the optic nerve, is examined with a light. Depending on the age of the child, this exam may be done under anesthesia. There are several types of eye exams that are done with the pupil dilated:               -  Ophthalmoscopy : An exam of the inside of the back of the eye to check the retina and optic nerve using a small magnifying lens and a light.      -  Slit-lamp biomicroscopy : An exam of the inside of the eye to check the retina, optic nerve, and other parts of the eye using a strong beam of light and a microscope.      - Fluorescein angiography : A procedure to look at blood vessels and the flow of blood inside the eye. An orange fluorescent dye called fluorescein is injected into a blood vessel in the arm and goes into the bloodstream. As the dye travels through blood vessels of the eye, a special camera takes pictures of the retina and choroid to find any blood vessels that are blocked or leaking.              -   RB1 gene test: A laboratory test in which a sample of blood or tissue is tested for a change in the RB1 gene.    -   Ultrasound exam of the eye: A procedure in which high-energy sound waves (ultrasound) are bounced off the internal tissues of the eye to make echoes. Eye drops are used to numb the eye and a small probe that sends and receives sound waves is placed gently on the surface of the eye. The echoes make a picture of the inside of the eye and the distance from the cornea to the retina is measured. The picture, called a sonogram, shows on the screen of the ultrasound monitor. The picture can be printed to be looked at later.    -  MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the eye. This procedure is also called nuclear magnetic resonance imaging (NMRI).    -  CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the eye, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.        Retinoblastoma can usually be diagnosed without a biopsy.   When retinoblastoma is in one eye, it sometimes forms in the other eye. Exams of the unaffected eye are done until it is known if the retinoblastoma is the heritable form.