glossary

Amniocentesis    A procedure that involves inserting a needle through the abdomen to the uterus of a pregnant woman in order to obtain the amniotic fluid which surrounds the developing baby.  The amniotic fluid can then be analyzed for the presence of the mistake that causes RB.

Anesthesia (General)    The complete absence of sensation and consciousness induced by drugs given intravenously (through a vein) or inhaled.  Under a general anesthetic, the patient is asleep during the surgery.

Anesthetist    The doctor who administers and monitors the anesthesia for the patients.

Bilateral RB    Children who develop RB tumors in both eyes have bilateral RB.  This form of RB is hereditary.  A child with bilateral RB has a 50% chance of passing RB to any of his future children.

Biopsy    A biopsy is the removal and examination of tissue from the living body in order to establish an exact diagnosis.  Biopsies are performed while a patient is under a general anesthesia.

Blood Counts    Blood counts are monitored to make sure that your child's blood levels are normal.  When tumors develop, cells in the body divide rapidly.  Chemotherapy acts on the rapidly dividing cells in your child's body and affects the bone marrow (the place where healthy blood cells are produced).  While your child is receiving chemotherapy, his blood counts will be taken twice a week (Monday & Thursday) to make sure that he is not at risk for an infection, necessitating hospitalization and antibiotics or in need of a blood transfusion. Only a small amount of blood is needed to monitor your child's blood counts.  The blood is taken from your child by a finger prick.  Taking blood from your child in this way reduces the number of needles he receives and, therefore, reduces his discomfort.

Bone Marrow    Bone marrow is a collection if special cells inside the long bones.  It is where new blood cells are produced.

Bone Marrow Aspiration    A procedure that involves the removal of a small amount of bone marrow, usually from the hip bone while the child is asleep during an EUA.  The bone marrow sample is analyzed for the presence of cancer cells that may have spread from the eyes through the blood.

Cancer    Cancer is a general term used from more than 100 diseases.  In cancer, cells are abnormal and grow in an uncontrolled way.  The resulting tumor can invade and destroy surrounding normal tissues.  Cancer cells from the tumor can spread through the blood or lymph to other parts of the body.

Cataract    A cataract is a lens that is no longer transparent, but rather is opaque (no, or little light can pass through it).  As a result of the lens transparency, the eye's visual function is significantly reduced and in some cases completely absent.  The surgical removal of the cataract and the insertion of a special contact lens in the place can retrieve a degree of vision. The patient should get back some of the lost vision after the surgery, but will require the use of corrective lenses.

CBC    Complete blood count.

Chemotherapy    Chemotherapy is a treatment using special drugs to control cancer cells.

Conformer    A conformer is a plastic shield similar to a prosthetic eye that is placed temporarily under the eyelid at the time of the enucleation surgery.  The custom-made prosthetic eye later replaces it.

Cornea    The clear outer portion of the eye.  It allows light into the eye.

Cryotherapy    Cryotherapy is a form of focal therapy whereby a frozen probe is held to the outside of the eye directly opposite a tumor.  The probe freezes the tumor turning it into an iceball.  As the frozen tumor thaws the cells break down and are destroyed.  A session of cryotherapy usually involves 3 cycles of freeze and thaw for each tumor.  Cryotherapy is performed on your child while he is under a general anesthetic.

CT Scan    A special x-ray used to examine parts of the body especially the head, i.e. the eyes and optic nerve.

CSF (Cerebral Spinal Fluid)    Cerebral Spinal Fluid is the fluid that surrounds the brain and spinal cord.

Diagnosis    The name for the disease or condition.  The diagnosis is determined after the doctor evaluates the findings from a physical or eye exam and lab and other tests.

Dilate    To dilate something is to make it wider or larger.  To see inside the eye it is necessary to dilate the pupil with eye drops.

DNA (Deoxyribonucleic acid)    

Enucleation    The surgical removal of the eyeball, leaving the eye muscles, lids and surrounding structures.

EUA (Examination Under Anaesthesia)    An examination of the entire area of your child's eye while he is under a general anaesthetic.  EUAs are used to monitor the state of the RB tumors in your child's eye(s).  Once his eyes are mature (at around 6-7 years of age) EUAs can be replaced with eye exams in the Ophthalmology clinic.  The child must be able to cooperate fully during the eye exam for it to be as effective as an EUA.

External Beam Radiation    Energy waves given off by certain substances or generated electronically that are used to treat as disease.  When used for treatment, these waves are directed to a tumor in order to destroy or inactivate it.

Extraocular Disease    Disease that exists or spreads outside of the eye(s).

Focal Therapy    Focal therapy is treatment applied directly to individual tumors.  Generally it is used to treat small, non-visually threatening tumors.  Focal therapy can be used as a primary treatment plan, however, it is also usually used in combination with chemotherapy.  Focal therapy includes 3 different types of treatment (laser therapy, cryotherapy and radioactive plaque).  These are used individually to treat specific sizes and locations of tumors, but are often used in combination throughout the treatment of a single child.

Fovea    The part of the macula adapted for most acute vision and colour vision.

Gene    The biological component that carries the information that determines the characteristics of each individual person. Genes are the information that is passed on from parents to offspring.

Genetic    A condition that has a hereditary component.

Heredity    The genetic transmission of a particular quality of trait from one parent to their children.

HSC    The Hospital for Sick Children

Implant    A plastic, silicone or coral sphere that is placed in the eye socket after the surgical removal of an eyeball.  It maintains the shape of the front of the eye and supports the prosthetic eye.

Informed Consent    This is the process by which a patient and or his family learn about all of the aspects of a medical treatment and its benefits and risks before agreeing to be treated.  It is a very important part of any medical procedure.  Treatment cannot begin until informed consent has been obtained.

Indirect Ophthalmoscope    An instrument that shines a bright light through your child's pupil and allows an ophthalmologist to see your child's retina.  The use of an indirect ophthalmoscope is not painful for your child, however, it can be uncomfortable for him because of the bright beam of light which has to shine through a dilated pupil.  For your children, the indirect ophthalmoscope is often used to examine a child who is asleep during an EUA.

Intravenous    Injection into a vein.

Iris    The coloured part of the eye.  The iris is responsible for controlling the amount of light that enters the eye.

Laser    A very narrow, high-energy beam of light used to destroy tumor tissue. (See picture to the left).

Lens    A clear structure in the eye which focuses light on the retina, in the same way the lens of a camera focuses light on film.

Leukocoria    A condition characterized by the appearance of a whitish reflex or mass in or behind the pupil.  Leukocoria is also referred to as a Cat's eye reflex, because its appearance is similar to that of a cat's eye.

Lumbar Puncture(LP)    If retinoblastoma has spread to the brain, the tumor cells may be floating in the cerebral spinal fluid (CSF) which bathes the brain and the spinal cord.  A lumbar puncture can test for the presence of these tumor cells.  To obtain a sample of the CSF for testing, a small amount of the fluid is drawn through a narrow needle at the base of the spine.

Macula   A small area at the back of the eye in the light sensitive layer (the retina) which allows us to see fine detail and colour. The closer a tumor a treatment scar is to the macula, the poorer the outcome for remaining vision.

Malignant    The tendency of cells to grow without control and spread to other parts of the body possibly resulting in death.

Metastasis    The migration of cancer cells from the original tumor site through the blood or lymph vessels to other parts of the body possibly resulting in death.

Mutation    A permanent change in the genetic material of a person or an organism.

MRI (Magnetic Resonance Imaging)    An imaging technique similar to a CAT scan but not using x-rays.  It is useful in displaying specific characteristics of the brain and eye.

Naturopathy    A drugless system of therapy and treatment.

Ocularist    A specialist who designs, makes and fits prosthetic (artificial) eyes.

Oncologist    A doctor who specializes in chemotherapy treatment for cancer.

Ophthalmologist    A doctor who specializes in the medical and surgical treatment of eye diseases.

Optic Nerve    The nerve that connects the eye to the brain.

Port-o-Cath   A device that is surgically inserted under the skin with a tube leading into one of the large veins leading to the heart, it is used to deliver chemotherapy drugs into the blood without risk of the drugs leaking into the normal tissue.

Prechemo-cryotherapy    Prechemo-cryotherapy refers to the use of cryotherapy less than 72 hours before chemotherapy to increase the penetration of the chemotherapy drugs into the eye.

Prosthesis    An artificial substitute for a missing body part, used for functional or cosmetic reasons or both.

Prosthetic Eye    The custom-made artificial eye that sits in the orbit of the enucleated eye.

Protocol    The outline or plan of treatment.

Pupil    The opening at the centre of the eye, through which light enters the eye.

Radiation Oncologist    An oncologist who specializes in the use of radiation therapy as a treatment for cancer.

Radioactive Plaque    A form of focal therapy whereby a thin flat disk filled with a radioactive substance is attached to the eye directly over the tumor.  It is designed to provide a carefully measured amount of radiation to the tumor.

Recurrence    The return of symptoms after a remission.

Retina    Nerve tissue lining the back of the eye that detects light and information and sends it to the brain.

Retinal detachment    When the retina has pulled away from the underlying layers of the inner eye.

RetCam    High resolution camera that takes pictures of the retina and retinoblastoma tumors.

Retinoblastoma (RB)    A rare form of cancer which causes tumors to grow on the retina of children. In most cases, the tumors began developing before the child was born.  RB can affect both eyes (bilateral RB) or it can affect only one eye (unilateral RB).  RB is caused by a mutation in the developing retina cells of the child.  This mutation can either have been inherited from either parent or it can be just a spontaneous mistake.  RB is completely cured in 96% of the cases with modern medical care.  While RB is a genetic disease, only about 5-8% of families have a positive family history.  In most cases, the affected child is the first family member to have RB.

Retinoma    A rare growth that simulates retinoblastoma and is caused by the same genetic changes, but stops growing without needing treatment.

RB Gene    The piece of DNA that causes retinoblastoma.  When the two copies of the gene are damaged in a cell of infant retina, tumor forms.

Sclera    The white outer covering of the eye.

Strabismus    An inward or outward turning of one or both eyes.

Tumor    New growth of tissue in which the multiplication of cells is uncontrolled and progressive.

UBM (Ultrasoundbiomicroscopy)    A high frequency ultrasound that displays an image of the anterior (front) part of the eye.  UBM is highly effective in the detection and monitoring of tumors that can not be seen with other imaging devices.

Ultrasound (B-Scan)    B-Scan ultrasound is a device used for evaluation structures that cannot be seen directly.  High frequency sound waves are reflected by eye tissues and orbital structures and are converted into electric pulses, which are displayed as bright spots on a black background.  It provides a cross-sectional view of tissues.

Unilateral RB    A child with unilateral RB has tumor only in one eye.  In most cases, unilateral RB is not hereditary.  However, 15% of children with unilateral RB do have the hereditary form of RB and so each of their children will have a 50% chance of developing RB.

Vitreous    The transparent jelly substance that fills the inside the eye and helps to maintain the internal pressure within the eye and the external shape of the eye.

Vitreous seeding    Vitreous seeding refers to little pieces of RB tumor that have broken away and are floating freely in the vitreous.  Vitreous seeds are dangerous because they can potentially land on the retina and begin growing into new tumors. They are also difficult to treat when they are floating in the vitreous, because they are too small and free-moving to treat with laser.  They also do not respond very well to chemotherapy as they are not attached to a blood supply.

All pictures courtesy of The Hospital for Sick Children  Toronto, Ontario