What Is Intravitreal Chemotherapy?

Intravitreal chemotherapy involves injecting chemotherapy drugs directly into the jelly-like substance in the eye known as the vitreous. This injection is done using a very small needle. It is typically used in cases in which eye tumors have not responded to other treatments. It may be given together with systemic treatment, which targets the entire body, or other medication.

In this article, we will look at the conditions treated, what the process is, and who performs this procedure.

Conditions

Intravitreal chemotherapy is used for some cases of retinoblastoma (cancer that starts in the back of the eye, most often found in children). This is a potent therapy usually reserved for those cases in which retinoblastoma tumors are discovered in the vitreous after other treatments have been tried and where treatment possibilities are limited.

Because the jelly-like vitreous does not have blood vessels, it is difficult to target the cancer with other types of chemotherapy, namely those delivered into the bloodstream or oral medications absorbed into the blood from the digestive tract. Also, laser treatment passes through the clear tumor seeds, making this ineffectual.

While radiation can help about half of the time, it can also cause secondary cancers and mutations.

Process

With this approach, the patient is first given general anesthesia to get the patient into a sleep-like state. Then an ultrasound (imaging using sound waves) is done to ensure that there is no tumor where the medicine is being injected. Verifying that no tumor is at the site enures that the needle will not puncture the tumor and allow tumor cells to leave the eye and spread elsewhere.

Also, some fluid may be removed to decrease pressure inside the eye. Then, chemotherapy agents such as melphalan or topotecan are given through a tiny needle. Sometimes just one of the agents is used and at other times, both are needed.

After injection, cryotherapy (uses cold to kill tissues) may be done at the location where the needle was inserted in the eye to help prevent any stray cancer cells from spreading.

Who Does It?

Intravitreal chemotherapy is a highly specialized technique. While it may not necessarily be difficult to perform this technique, it's important to find a provider who knows how to minimize risk with the approach.

The concern is that if an ophthalmologist (specialist in medical and surgical eye care) or retinal specialist (specialist in the light-sensing layer at the back of the eye) who is unfamiliar with intravitreal chemotherapy does the injection, there may be a risk of spreading tumor cells elsewhere in the body.

Typically those with retinoblastoma are treated by a team of doctors, including a pediatric ophthalmologist, an ocular oncologist, a pediatric oncologist, and a radiation oncologist. Oncologists are specialists in treating cancer.

The intravitreal chemotherapy approach should only be performed by a team member who understands the risks and is experienced at minimizing them.

Eligibility

Intravitreal chemotherapy is not for patients in the initial stages of retinoblastoma treatment who have not tried other, more traditional approaches. Rather, this is strictly reserved for those who have tried other treatment approaches with lingering tumors in the vitreous.

This therapy is often reserved for those for whom other options have been tried, and eye removal is a consideration.

Outcomes

The intravitreal chemotherapy approach can be more potent than traditional intravenous chemotherapy (infused through a line into the bloodstream).

Intravitreal chemotherapy is particularly useful against tumors in the vitreous known as vitreous seeding. Traditional chemotherapy and radiation treatment results have been poor in these cases, and eye removal becomes necessary for some.

However, it has been found that intravitreal injections can be successfully used to treat vitreous tumors in some cases. This potent approach has been promising in many cases. Some study results have shown that 81% of eyes with vitreous tumors were saved with intravitreal chemotherapy, and in others, the success rate is as high as 87%.

Side Effects

Since intravitreal chemotherapy is injected right into the vitreous, most of the side effects tend to impact only nearby tissues. However, there can be serious issues. Namely, every time the treatment is given, it has the potential to affect the retina (the light-sensing layer at the back of the eye) which can ultimately impact vision.

With the use of intravitreal melphalan, side effects can include issues such as:

• Uveitis (inflammation of the layer at the center of the eye)
• Endophthalmitis (inflammation of the aqueous and vitreous humors)
• Vitreous hemorrhage (bleeding in the vitreous)
• Retinal tears
• Cataract (clouding of the lens of the eye)
• Retinal detachment
• Tumor metastasis (spread)
  

Summary

Intravitreal chemotherapy is a potent option for those who have retinoblastoma tumors in the vitreous and have not responded to other approaches. Since this jelly-like substance has no blood supply, getting the treatment close to the tumors is essential. With this approach the chemotherapy is injected into the vitreous with a tiny needle.

The main concern with intravitreal chemotherapy is that tumor cells will be spread via the injection site. So, it is important to work with someone experienced with this approach.

A Word From Verywell

Retinoblastoma most often is found in children, and it can be a challenging time for families as they face treatment options. Tumors in the vitreous can be difficult to treat, but intravitreal chemotherapy can be successful. In many cases, it can help those who have not responded to other approaches and may ultimately spare the eye.