A subconjunctival injection is a medical procedure used to deliver medication into the space just beneath the conjunctiva, the clear membrane covering the white part of the eye. This method allows for a high concentration of a drug to be administered directly to the eye, increasing its absorption and duration of action. This approach is chosen when a direct and sustained therapeutic effect is needed for the front structures of the eye.
Medical Conditions Treated
This type of injection is often employed when standard topical treatments like eye drops are insufficient to control a serious ocular condition. It is a common treatment for severe eye inflammation, such as uveitis, which affects the middle layer of the eye. By delivering corticosteroids directly to the area, the injection can effectively reduce the inflammation and help preserve vision. The procedure is also used for serious eye infections like bacterial keratitis (a corneal ulcer) or endophthalmitis, an infection inside the eyeball itself, where delivering a potent dose of antibiotics is necessary.
In some cases, a subconjunctival injection is performed at the conclusion of eye surgery to administer antibiotics or anti-inflammatory medications as a preventative measure. This helps to reduce the risk of post-operative infection and control swelling. Additionally, certain medications called antimetabolites can be administered this way to prevent scarring after glaucoma surgery.
The Injection Procedure
The process begins with the thorough application of local anesthetic eye drops to completely numb the surface of the eye, ensuring the procedure is free of pain. These drops may be instilled multiple times over a period to achieve the desired numbing effect. The area around the eye is also cleaned with an antiseptic solution to prevent infection.
To perform the injection, the physician will use a small instrument to gently hold the eyelids open. You will be asked to look in a specific direction, away from where the needle will be inserted. This positioning allows the doctor to access the target area easily and safely. The physician then uses a very fine needle to inject the medication just under the thin, clear conjunctival tissue.
Most people report feeling a sense of pressure on the eye rather than a sharp pain during the brief injection. The entire procedure is very quick, often taking less than a minute to complete once the eye is prepared. After the needle is withdrawn, a sterile pad may be held against the eye for a moment.
Recovery and Aftercare
Immediately following the injection, it is common and expected to see a red patch on the white of your eye. This is a subconjunctival hemorrhage, which is essentially a small bruise at the injection site. This spot of blood is harmless and will gradually fade and disappear on its own over one to two weeks. You may also notice the small, raised bleb where the medicine was injected, which will also resolve as the medication is absorbed by the eye.
Mild discomfort, irritation, or a gritty sensation is normal once the anesthetic wears off. Your doctor may provide lubricating eye drops to soothe this feeling. It is important to avoid rubbing the eye, as this can cause irritation or a scratch on the cornea. Most patients can resume their normal daily activities within 24 to 48 hours, though it is often recommended to avoid swimming or wearing contact lenses for a couple of days.
While mild symptoms are normal, you should contact your doctor if you experience severe eye pain, a significant decrease in vision, or see an increase in discharge from the eye. These could be signs of a rare but more serious complication, such as an infection.