Intravitreal Eye Injections- Why and When Needed
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Throughout recent history, intravitreal eye injections have been used as a method to deliver those medications into the retina in the back of the eye that is not possible to be administered through normal eye drops and pills. Intravitreal injections were first used by Ohm in 1911 for repairing retinal detachments. For many decades, antibiotics were the only agents injected intravitreally. However, recent past has witnessed a major change in intravitreal pharmacotherapy, with more than a million such eye injections being delivered regularly since past few years.
The primary benefit of administration of eye injections is that it results in targeted procedure while minimizing systemic absorption of therapeutic agents. Intravitreal eye injections are administered for a range of retinal disorders including wet macular degeneration, diabetic retinopathy, glaucoma etc. Some common medications injected include Lucentis, Avastin, Eylea, Kenalog etc., though the preference of one over the other would depend upon the types of symptoms, the severity of the problem etc.
When and Why are Intravitreal Eye Injections needed?
As stated earlier, intravitreal eye injections are used to treat almost all retinal vascular disorders. Some of the eye disorders that may prompt your ophthalmologist to opt for eye injections include-
Diabetic Retinopathy- One of the leading causes of death in the world, diabetes has a great impact on almost all organs of the body, including the eyes. Diabetic eye disease or diabetic retinopathy is a debilitating condition of the retinal cells ultimately leading to blindness. In fact, among Americans of working age, diabetes is the leading cause of new cases of blindness. The classic symptoms of this disease include increased thirst, frequent urination, weight loss, and lack of energy.
Retinal Vein Occlusions- Retinal vein occlusions are normally blood clots blocking the retinal veins. It may be caused due to diabetes, high blood pressure, increased cholesterol levels etc. If not treated, it may lead to macular oedema, neovascularization, glaucoma and even blindness.
Age-related Macular Degeneration- Age-related macular degeneration (AMD), is the ageing of the outermost layer of the retina, mainly found in adults over the age of fifty. It is the cause of severe visual impairment in at least 2 percent of Americans over the age sixty-five. At its most devastating, AMD results in severe visual impairment and often overwhelming challenges to the quality of life. There are two basic forms of AMD- a dry form of AMD which features slow progressive, degenerative changes in the retinal cells and a wet, or exudative form of AMD is a faster, more aggressive process that can have a much greater impact on vision.
Glaucoma- Glaucoma is not simply a disease but a collection of eye problems that elevates the pressure within the eye, resulting in damage to the optic nerve and serious impediments to vision. Recent advances in medical science have enabled glaucoma to be treated with eye injections, wherein the eye pressure is lowered by using a hypodermic needle to inject a drainage tube into the eyes, allowing the excessive drainage to flow out.
Typically, an intravitreal eye injection must be taken as soon as the symptoms of the above diseases become known to the patient. Regular consultations with your ophthalmologist are, therefore, a must.
Risks and Complications
The single most important risk of intravitreal injections includes infection. Though such a risk is inherent in any intervention in the body, due to the delicate nature of the retinal cells, it can be more damaging than others. At the most extreme, treatment of infections may require surgery and may still result in permanent vision loss. In diabetes, this risk can be minimized by ensuring the level of blood sugar at the time of injection is normal. However, it is also important to note that risk of vitreous bleeding is negligible due to eye injections.
Further, as with any other surgical procedure, there may be possible complications due to eye injections. Some major complications include-
Endophthalmitis- Endophthalmitis is an inflammation of the interior of the eye. Though the incidence of endophthalmitis is rare, it can cause devastating damage to the vision of the eyes.
Subconjunctival Hemorrhage- This is a common but relatively minor complication, which occurs since the intravitreal injection needle must pass through the conjunctiva. Patients on antiplatelet or anticoagulation medication are at particular risk. If this occurs, it is best to explain to the patient that it should resolve in a week or so.
Problems Associated with a Dilated Pupil- In some susceptible individuals, dilating a pupil can cause the intraocular pressure to rapidly rise (“acute glaucoma”). This risk is rare and if there is a concern that needs to be addressed, it should be discussed with an ophthalmologist prior to dilating the pupil.
Corneal Abrasion- The cornea can be traumatized by the insertion of the speculum or a wayward needle. If the cornea is damaged, then inform a doctor who can assess further and consider additional treatment or altered follow-up.
Posterior Vitreous Detachment and Retinal Tears/Detachment- An intravitreal injection can cause the posterior lining of the vitreous to detach from the retina. If the intravitreal needle enters the eye too posteriorly or is angled too posteriorly then the retina can be torn. Failure to detect and treat a retinal tear can result in the development of a retinal detachment and permanent loss of vision.