The risks and complications of injections into the eye are low. The most dreaded complication of intravitreal injections is infection inside the eye (aka endophthalmitis). The risk of endophthalmitis is reported to be about 0.09%. Endophthalmitis can cause blindness.
As more and more intravitreal injections are delivered for the treatment of diabetic retinopathy and wet macular degeneration, the concern for causing blinding infection becomes greater. The rates of infection have always been low, in fact, so low, it is difficult to estimate and study.
Complications of intraocular injections include;
Retinal Detachment and Infection are the biggest concern. The other “complications” are rather soft and either don’t cause damage or are reversible (cataract and vitreous hemorrhage).
Retinal detachment can occur if the needle enters the eye in the wrong spot and causes a hole/tear in the retina. Additional surgery may be needed depending upon when this complication is diagnosed. Retinal detachments can potentially cause permanent loss of vision depending upon timing.
Endophthalmitis is a nightmare. It may occur in any intraocular procedure where the eye is penetrated by a surgical instrument. It happens so infrequently, that it is difficult to really measure the rate at which it occurs and to study just how it occurs. In theory, bacteria on the outside of the eye gets inside. Does this happen during surgery, or, after? We don’t really know.
You Have a Dirty Mouth – The eye, nose and mouth are all connected. This is why you blow your nose after crying. Your eye is as dirty as your mouth and nose. There is a lot of bacteria that can cause an infection.
Pre-Operative Antibiotics are controversial. In theory, it makes sense to treat the eye with antibiotics prior to anticipated surgery or injection. Many cataract surgeons prescribe antibiotic drops prior to surgery, but many don’t. The rate of infection is so low, it is hard to measure. Many retina specialists prescribe antibiotic drops prior to intraocular injection, but many don’t (I do).
A study was just published that found no difference in the rate of infection between using antibiotics before (and after) injection compared to no antibiotics. Over 3800 injections were studied. What is crucial; however, is the use of a lid speculum (small wire device that keeps the eyelids spread apart) and the application of a topical iodine/povidone antiseptic.
What Does This Mean? My point is to highlight that the risk of blindness due to infection is low in intraocular injections. As injections become more widely used for diabetic retinopathy and macular degeneration, we’ll be able to better define the rate and causes of this potentially blinding complication. Incidentally, as the use of sustained release technology is emerging, infection will become less of a concern as fewer ‘injections” will be necessary.