Intravitreal injection (IVI) is a standard medical procedure used to treat serious conditions affecting the back of the eye, such as age-related macular degeneration (AMD) and diabetic retinopathy. This process involves delivering medication directly into the vitreous humor, the gel-like substance that fills the eye’s interior. A common side effect immediately following this injection is the appearance of floaters, which patients see as temporary spots, specks, or shadows moving within their field of vision. Understanding the nature of these floaters is important, as their duration varies depending on the cause.
The Cause of Post-Injection Floaters
Floaters appearing directly after an eye injection result from physical material temporarily suspended in the vitreous humor. The most common source is a tiny, sterile air or gas bubble introduced during the injection process. This small bubble rises within the eye, creating a circular floater often noticed in the lower part of the patient’s vision. Because the bubble is light, it casts a shadow on the retina, perceived as a moving dark spot.
The second cause is the visible presence of the injected medication itself, particularly with certain drug formulations. Medications formulated as suspensions, such as the steroid triamcinolone acetonide, consist of fine crystals injected into the eye. These crystals do not immediately dissolve, appearing instead as a cloud or collection of white deposits that interrupt light transmission to the retina. Floaters can also result from silicone micro-droplets used to lubricate the syringe barrel, which separate into the medication.
Typical Duration and Resolution Timeline
The duration of post-injection floaters depends entirely on the physical material causing them. Floaters caused by the small air or gas bubble resolve the fastest because the eye’s internal environment absorbs the gas. Patients typically see this circular floater shrink and disappear within hours, or at most, within one to three days. As the air bubble is absorbed, the floater diminishes until it is no longer visible.
Floaters resulting from the medication itself follow a much slower resolution timeline. For common anti-VEGF medications used to treat macular diseases, visible specks are usually reabsorbed within a few days to one or two weeks. Floaters caused by steroid suspensions, such as triamcinolone, persist significantly longer due to the drug’s particulate nature. These medication crystals are designed to dissolve slowly to provide a long-acting therapeutic effect, meaning they remain in the vitreous for an extended period.
Floaters from steroid crystals can remain visible for weeks or even months as the particles slowly dissolve and are absorbed by the eye’s systems. These fine opacities have been observed to persist for over 120 days, though they often settle out of the direct line of sight over time. While the extended duration may be concerning, it is a normal characteristic of the medication’s intended slow-release mechanism. Floaters caused by silicone micro-droplets do not dissolve but may move away from the central vision, becoming less bothersome.
When to Contact Your Eye Doctor Immediately
While temporary floaters are an expected side effect, certain symptoms indicate a complication requiring immediate medical attention. The most serious concern is endophthalmitis, a rare but severe infection inside the eye that demands urgent treatment. Symptoms of this condition typically develop within the first few days to a week after the injection.
Patients should contact their eye doctor immediately if they experience severe or worsening eye pain that persists beyond the initial recovery period. A sudden, marked decrease in vision or a noticeable worsening of vision after the first day is also a red flag. Furthermore, a sudden increase in the number or density of floaters, sometimes described as a shower of black spots, is a symptom of concern.
Other indications of a potential issue include new flashes of light (photopsia) or the development of a dark shadow, like a curtain or veil, moving across the visual field. This shadow can signal a retinal tear or detachment. Increasing redness, swelling, or discharge from the eye are signs that an infection or significant inflammation may be present.