Mr. Blackworth had just returned from his family doctor. “Dr. Smith said that I have high blood pressure just like you saw!” he exclaimed. I had just examined his retina last week. “What damage can high blood pressure do to my eyes?” he asked anxiously.
High blood pressure is a risk factor for a number of retinal disorders but most commonly it can lead to blockage of the veins in the retina. When the blood cannot leave the eye it causes bleeding and fluid build up in the retina. This can lead to decrease in blood flow into the retina also and cause the cells to die. When one of the four main veins is blocked it is called a branch retinal vein occlusion. If the vein in question is located above the macula which is the center part of the retina that does the fine seeing, then severe vision can result. Treatment such as laser or injections of medication into the eye are used. Vision often improves but most patients notice a decrease in the quality of the vision even with treatment. Branch retinal vein occlusions can lead to new blood vessel growth and the eye can fill with blood and eventually become blind. If this process is detected early on then another type of laser treatment can reverse it. Otherwise if there is too much blood to successfully treat with laser, invasive surgery in the operating room is recommended.
If the two upper or two lower veins are blocked then this is called a hemiretinal vein occlusion. As might be expected there is twice as much damage and is even more serious than the branch retinal vein occlusion. The treatment is the same but the results and prognosis are worse. A central retinal vein occlusion involves all four veins at the point where they enter the eye. Studies have shown that unlike in the case of the branch retinal vein occlusion, laser treatment does not help improve or even stabilize vision. Laser is often necessary to prevent the eye from becoming blind and painful. Over the past 5 years, retina specialists have used injections of medication into the eye to return vision and I have seen some remarkable recoveries first hand. Unfortunately, the effect is short lived and the majority of patients need injections every 1 to 2 months.
The bottom line is that high blood pressure can have serious effects on the retina. It is important to work with your medical doctor to control it and let your eye doctor know even though many times we can see it by looking into your eyes!