Definition
Retinoblastoma is a malignancy in the eye that predominantly affects children. Among the various tumors that commonly occur in young children, retinoblastoma ranks as the third most prevalent eye tumor. The incidence of retinoblastoma ranges from 1 in 14,000 live births to 1 in 20,000 live births. Approximately 90% of retinoblastoma cases manifest in children under the age of three years.
Causes
Retinoblastoma occurs from mutations or changes in a gene known as RB1. Under normal conditions, the RB1 gene functions to suppress excessive cell growth. This gene, inherited from both parents, only leads to retinoblastoma if mutations occur in both copies of the RB1 gene. The mutation causes retina cells, which are responsible for receiving light, to proliferate uncontrollably.
Mutations in the RB1 gene can be congenital or occur during development. If the RB1 gene mutation is inherited, the mutation can be passed down, increasing the risk of retinoblastoma in offspring. Furthermore, this inherited mutation elevates the risk of tumors in other body parts because the gene is mutated in all cells. Retinoblastoma can develop in one or both eyes.
Risk Factor
Retinoblastoma incidence does not vary based on gender or race. Children are typically diagnosed around 18 months of age, with 90% of cases identified before five years old. Only 5% of retinoblastoma cases are found to be inherited in their family, while the remaining 95% occur sporadically. About 90% of cases affect one eye and are non-hereditary. The risk for siblings or descendants of retinoblastoma patients is 1%.
Symptoms
The most recognizable symptom of retinoblastoma is the cat's eye reflex, where the center of the eye appears white when exposed to light due to tumor cells reflecting the light. Other common symptoms include crossed eyes, eye redness with pain, inflammation of the eyelids or surrounding skin, lumps outside the eyes, decreased vision, and impaired eye movement.
Diagnosis
The process of diagnosing retinoblastoma often commences with a thoughtful review of the family’s medical background, which can offer essential clues regarding this eye condition. The doctor typically begins by asking about any instances in the family history of blindness, eye tumors, childhood cancers, or even previous surgeries involving the removal of an eyeball (enucleation). Additionally, the doctor may inquire about the first time you noticed your child’s eyes turning white when exposed to light—a phenomenon sometimes observed in photographs or under bright illumination.
Next, the doctor will perform several direct tests to assess the health of your child’s eyes. The initial step involves a test of visual acuity that is specifically tailored to the child’s age, with each eye being evaluated separately. During this test, the physician may request that the child identify or follow objects. Following the visual acuity test, a light is shone into each eye to observe the natural light reflex, a response that helps in assessing the integrity of the retina and other internal structures. In addition to these tests, the doctor conducts a careful inspection of the external aspects of the eye, examining the eyelid and the surrounding skin for any signs of inflammation or irritation. Moreover, a specialized test using a slit lamp is administered to take a closer look at the anterior segment of the eye. This test is designed to detect redness, any accumulation of pus within the eye, abnormal new blood vessel formation in the iris, and early indicators of glaucoma, which is a serious condition that can lead to optic nerve damage if left unchecked.
To gain a more detailed view of the internal structures of the eyeball, the physician will then proceed with a comprehensive test known as fundoscopy. In preparation for this test, your child will be given medication to dilate the pupil. In some cases, anesthesia may also be provided to ensure that the child remains comfortable and still during the process. The fundoscopy test is indispensable not only for confirming the presence of retinoblastoma but also for determining the exact location, dimensions, and severity of the tumor. This test is performed on both eyes.
Following the detailed internal test, an ultrasound test is frequently used as an initial imaging tool; it creates a detailed picture of any mass or tumor within the eye and allows the doctor to measure its length, width, and height with precision. Alongside the ultrasound, an MRI test is also conducted to investigate whether the tumor has extended its reach, especially along the optic nerve. CT scans are generally avoided in children with retinoblastoma. The reason for this is that the radiation exposure associated with CT tests can increase the risk of developing other malignancies later in life, particularly if the child carries a mutation in the RB1 gene.
Specialized tests such as genetic tests and tumor tissue tests can also be performed. Genetic tests play a critical role by identifying whether the retinoblastoma is linked to an inherited mutation. These tests are not confined solely to the affected child; they are also extended to the parents and siblings. On the other hand, tumor tissue tests can also be performed to analyze the cells that make up the tumor.
Management
Management of retinoblastoma requires a multidisciplinary approach involving ophthalmologists, pediatric oncologists, geneticists, other healthcare professionals, and parents. Several therapeutic methods can be employed:
- Chemotherapy: The primary treatment for retinoblastoma, using drugs to destroy or inhibit tumor growth. These drugs can be administered intravenously or directly into the eye.
- Transpupillary Thermal Therapy (TTT): This technique uses heat to cut off the blood supply to the tumor and can be used alone or with chemotherapy.
- Cryotherapy: This method freezes the tumor tissue, causing it to die.
- Brachytherapy: This involves placing a radiation source close to the tumor to destroy tumor cells.
- Radiotherapy: Utilized to eliminate tumor cells but must be used cautiously due to the risk of inducing malignancy elsewhere.
- Enucleation: Surgical removal of the eyeball is considered if chemotherapy fails, the tumor recurs, or if the tumor invades the forepart of the eye. After the enucleation, the child may undergo chemotherapy if residual tumor cells are present.
After the therapy, regular follow-up visits are planned to monitor tumor progression and assess visual function.
Complications
Untreated retinoblastoma can lead to severe complications, including metastasis or tumor spread to other parts of the body such as the optic nerves, brain, bones, lymph nodes, and surrounding tissues. Other than that, ocular complications including retinal detachment, retinal cell death, cataracts, and glaucoma. This can potentially result in blindness.
Prevention
While retinoblastoma cannot be prevented, early recognition is possible. If there is a family member with a history of blindness or eye tumors in childhood, it is advisable to have the child screened for retinoblastoma by an ophthalmologist.
When to See a Doctor?
Immediate medical consultation is necessary if you observe a white reflection in your child's eye when exposed to light or if the child has crossed eyes. These symptoms are commonly associated with retinoblastoma and can also indicate other treatable eye conditions. Prompt and specialized treatment is crucial to prevent tumor spread and avoid permanent blindness.
Looking for more information about other diseases? Click here!
- dr Hanifa Rahma
Choe, C., O'Brien, J., Phelps, P., Bacal, D., Miller, A., & Epley, K. (2021). Retinoblastoma - EyeWiki. Retrieved 15 November 2021, from https://eyewiki.aao.org/Retinoblastoma
Ishaq, H., & Patel, B. (2021). Retinoblastoma. Retrieved 15 November 2021, from https://www.ncbi.nlm.nih.gov/books/NBK545276/
Isidro, M. (2019). Retinoblastoma: Background, Pathophysiology, Epidemiology. Retrieved 15 November 2021, from https://emedicine.medscape.com/article/1222849-overview#showall
