Eye floaters are small spots, specks, or threads that appear to drift across a person’s field of vision. These phenomena are most often a harmless consequence of the natural aging process, where the eye’s internal gel begins to liquefy and shrink. While most floaters are benign, some cases are attributed to systemic side effects from prescription medications. This relationship involves the drug’s effect on the delicate structures inside the eye, leading to the formation of visible debris. Understanding this connection helps patients recognize when a new medication might be the source of their visual changes.
Understanding the Mechanism of Drug-Induced Floaters
Medications can lead to the creation of eye floaters by directly altering the physical environment inside the eye. The eye is filled with the vitreous, a clear, gel-like substance composed of water and collagen fibers. Floaters appear when the vitreous gel changes composition, causing microscopic debris to form and cast shadows on the retina.
One mechanism involves the drug causing inflammation, known as uveitis or vitritis, in the eye’s internal structures. This inflammation introduces cellular debris and inflammatory byproducts into the vitreous gel, which the patient perceives as new floaters. Another pathway is the direct precipitation or crystallization of drug molecules within the vitreous chamber. Substances, particularly those administered directly into the eye, can form tiny crystals or aggregates that float freely.
Drugs can also accelerate the natural breakdown of the vitreous gel, a process called syneresis. When this liquefaction is sped up, collagen fibers clump together more rapidly, leading to a posterior vitreous detachment (PVD) and the appearance of a large, distinct floater. Understanding these chemical and structural changes helps explain why a drug taken for an unrelated condition might manifest a visual side effect.
Medications Associated with Causing Floaters
A variety of systemic medications have been linked to inducing or increasing eye floaters through the mechanisms of inflammation, crystallization, or accelerated vitreous change. These associations are often dose-dependent or related to long-term use.
Antibiotics and Anti-Infectives
Certain antibiotics, specifically those in the fluoroquinolone class, have been associated with changes in the vitreous structure. Studies suggest these drugs may alter the vitreous balance, potentially increasing the risk of acute posterior vitreous detachment and, rarely, retinal detachment. It is hypothesized that they impact the collagen matrix within the eye. Other anti-infective agents, such as ethambutol used for tuberculosis, are known to cause ocular toxicity, sometimes accompanied by inflammatory reactions that create floaters.
Corticosteroids
Corticosteroids, powerful anti-inflammatory drugs like prednisone, are widely used for numerous conditions. Their long-term or high-dose systemic use increases the risk of several ocular side effects, including cataract formation. Corticosteroids can also induce or worsen floaters by increasing intraocular pressure or when administered directly into the eye, such as with intravitreal triamcinolone, a crystallized steroid that causes sterile inflammation and floaters.
Immunomodulators and Antimalarials
The antimalarial drug hydroxychloroquine (Plaquenil), often prescribed for autoimmune diseases, is recognized for its potential to cause retinal toxicity. The inflammatory processes linked to its use may also contribute to the presence of floaters. Other immunomodulators, such as bisphosphonates used for osteoporosis, have been reported to cause inflammatory conditions like uveitis, which releases debris into the vitreous chamber and results in new floaters.
Ophthalmic and Cardiovascular Medications
Specific medications administered directly into the eye, such as anti-vascular endothelial growth factor (anti-VEGF) agents used to treat wet macular degeneration, can cause sterile inflammation. This inflammation may present with floaters and blurred vision shortly after injection. Systemic drugs, including statins and various antidepressants, have been anecdotally associated with visual disturbances, but a direct causal link is less established compared to inflammatory agents.
What to Do If You Suspect Your Medication is the Cause
If you notice a sudden appearance or a significant increase in floaters after starting a new medication, schedule an appointment with your prescribing physician or an ophthalmologist. You should not abruptly discontinue any prescription medication without first consulting the doctor who prescribed it.
A dilated eye examination is necessary to determine the source of the floaters and rule out serious conditions. The eye doctor will distinguish between benign, age-related floaters and those caused by drug-induced inflammation or a retinal tear. Providing a complete list of all medications, including over-the-counter drugs and supplements, is helpful for the physician to assess the potential drug-related link.
A sudden onset of new floaters, especially if accompanied by flashes of light, requires immediate medical attention. These symptoms are considered red flags and could indicate a retinal tear or retinal detachment, which is a medical emergency that can lead to permanent vision loss. Other urgent signs include a dark curtain or shadow moving across your vision or a sudden loss of peripheral sight. Any acute change in vision warrants an emergency evaluation.