Systemic Diseases Manifested In the Retina

By Omar Ahmad, MD

The retina is the specialized part of the eye that is in the back part of the eye that collects all the light that is focused on to it from the front parts (cornea, lens). It takes that information and converts it into electrical signals that are then collected in the optic nerve and transmitted to the brain.

The retina is constantly functioning. Therefore, it needs a constant blood supply; the flow to the retina and support structures is constantly refreshing the retina. The main supply of nerves and blood flow to the entire eye also comes through the retina. This makes for a very dense collection of vessels and nerves in the retina.

Because of this constant flow of blood to the retina and surrounding structures, most systemic diseases to some extent affect them. Systemic diseases are any diseases that are present throughout the body. Some common examples are diabetes, hypertension, hyperlipidemia, lupus, sarcoidosis, and cancers. The effect on the retina can be very large or subtle.

There are also some treatments or medications that can collect in the retina because of this relatively large blood supply. Many times your primary doctor or specialist will start you on a medication and ask that you get a baseline retina exam to make sure any changes while on the medication are detected.

The retina can be viewed with just dilation of the iris. There is no radiographic tests or other invasive tests needed as in other structures of the body. Also, the retinal blood vessels and other structures are quite fine. They tend to show signs of damage earlier than some of the larger or more robust structures in the body. These two facts make a retinal exam a must for many systemic diseases and also help catch some systemic diseases with just a dilated exam.

The treatment for these diseases is usually improved control or treatment of the underlying disease in the long term. The retinal treatment is usually secondary. For example, bleeding and edema in the retina from diabetes is treated with retinal lasers, injections, or drops. But for long-term results and stability, diabetic control is a must. To use an analogy, if a boat has a leak and is taking on water, we need to start bailing water to keep the boat afloat and save it. The true fix, however is to patch the leak.

The full extent of retinal findings that are related to systemic conditions or medications is enormous. Your primary eye doctor or doctor treating your systemic conditions can advise you if a retinal exam is needed for your disease or treatment. The retina is easily damaged and vision can be lost permanently. If a retinal exam is advised, please make sure you follow their recommendations.