Eye floaters are small spots, specks, or thread-like shapes that drift across the field of vision. These shapes are shadows cast onto the retina by debris suspended in the vitreous humor, the gel-like substance filling the eyeball. Chemotherapy is a life-saving treatment, but it acts systemically, affecting cells throughout the body, not just cancer cells. This broad action often leads to side effects, including those affecting the eye and visual system. Understanding the connection between chemotherapy and vision changes, such as new floaters, is a concern for patients undergoing treatment.
The Link Between Chemotherapy and Eye Floaters
Chemotherapy does not typically cause floaters through the direct breakdown of the vitreous humor. Floaters during treatment often signal an underlying issue caused by drug toxicity or secondary complications, such as inflammatory cells or blood in the vitreous cavity.
Certain chemotherapy agents are known to cause uveitis, which is inflammation within the eye. This inflammation leads to the accumulation of cells or fluid that cast shadows, resulting in the perception of floaters. Some targeted therapies, such as the MEK inhibitor Trametinib, have been associated with developing floaters.
The taxane-based drugs docetaxel and gemcitabine have been linked to posterior segment toxicity and retinal changes. The immune system is often compromised during chemotherapy, making the eye vulnerable to infection or secondary complications. Retinal toxicity from drugs like cisplatin can cause retinal hemorrhages or debris within the vitreous. Bleeding into the vitreous humor (vitreous hemorrhage) causes a sudden onset of floaters, and chemotherapy-induced low platelet counts can increase this risk.
Broader Ocular Side Effects of Chemotherapy
Chemotherapy can trigger a wide range of ocular side effects due to its impact on rapidly dividing cells on the eye’s surface. A frequently reported issue is dry eye syndrome, where treatment disrupts the normal function of the tear film or lubricating glands.
Another common side effect is excessive tearing, medically termed epiphora, which can occur with drugs like capecitabine, 5-fluorouracil, and doxorubicin. This is often due to inflammation or stenosis, a narrowing of the tear drainage ducts that prevents proper drainage.
Some patients also experience conjunctivitis, an inflammation of the clear membrane covering the eye, presenting as redness, swelling, or discharge. Chemotherapy can also cause photophobia, an increased sensitivity to light, reported with drugs like cytarabine and methotrexate. Blurred vision is a generalized symptom arising from drug-induced changes, including corneal deposits or macular edema (swelling in the central retina). These effects are generally managed with supportive care and may resolve after treatment concludes.
When to Seek Urgent Medical Attention for Vision Changes
While the gradual onset of benign floaters is common, certain visual symptoms during chemotherapy require immediate medical evaluation. A sudden increase in the number of floaters, especially when accompanied by flashes of light (photopsia), suggests possible pulling or traction on the retina.
A medical emergency is indicated if a shadow or curtain appears to move across the field of vision. This symptom suggests a retinal detachment, where the light-sensitive tissue separates from its underlying support layers. Retinal detachment is painless, but without prompt treatment, it can lead to permanent vision loss.
Other urgent symptoms include sudden, significant vision loss, eye pain, or changes in peripheral vision. Since chemotherapy suppresses the immune system, severe eye pain or redness could indicate a serious infection within the eye. Patients should contact their oncologist and ophthalmologist immediately if any urgent symptoms develop, as early intervention is essential to preserving vision.