What are these injections for macular degeneration?
Macular degeneration is a condition that affects the central part of the retina. We see this condition as patients age. Patients’ symptoms can be a central blur or distortion in mild macular degeneration. In more advanced macular degeneration, patients may see large patches that are grey or black obscuring most of the central vision.
These symptoms can affect one or both eyes and can be mild in both eyes, mild in one eye and severe in the other eye or severe in both eyes. The disease can be variable.
The two types of macular degeneration are dry and wet.
Dry age-related macular degeneration refers to the natural ageing of the macular where areas of the retina wear away.
Wet age-related macular degeneration refers to the growth of new abnormal leaking blood vessels under the macula. That can lead to rapid loss of central vision.
The main treatment for wet age-related macular degeneration is intravitreal injections. We don’t currently use intravitreal injections for dry age-related macular degeneration. But, studies are looking at whether we can use injections to treat this condition.
Why do we give injections into the back of the eye rather than using eye drops or tablets?
That is because they are large molecules, which cannot get to the eye through the eye drop or tablet route. The only way to get them close to the retina is to inject them into the back of the eye (the vitreous cavity).
It is too difficult to inject these medicines into the retina itself as the retina would bleed and we might damage it with a needle.
The vitreous cavity acts a bit like a reservoir as it is full of gel and doesn’t have a useful function, so needles can safely deliver the medicine.
Giving an intravitreal injection is also easy and painless. Plus there is little risk of complications such as infection or retinal detachment.
The trade-off is that we have to keep giving the injection treatment regularly as the medicine wears off quickly. Many patients have many monthly injections to get the desired treatment effect.