Macular Degeneration

One of the most important causes of decreased visual acuity in the elderly is disturbance of the point with best visual acuity due to aging (macular degeneration). It is usually observed in both eyes, though with different degrees. This disease occurs after the age of 60 years and progresses in various stages. It starts with slow loss and aggregation of pigment epithelium. The sensory cells found in the middle of the retina are also affected by this change. This stage is called dry macular degeneration.

Approximately 10% of the patients progress to the stage called wet macular degeneration. Here, small vessels form together with vascular connective tissue below the middle retina. These grow below the pigment epithelium as tissue and extend. Most of the time, fluid leaks from the vessels. Sometimes, hemorrhages occur below the point with best visual acuity as a result of rupture of vessels. After blood is absorbed, a scar in the shape of a disc is formed, and destructed sensory cells remain in the final stage. The disease may last for years, but a scar may occur in a few months.

At the beginning of the disease, which occurs without pain, a hidden worsening of visual acuity occurs, and this makes reading especially difficult. Objects that are looked at directly are seen blurry. At the time of transformation from the dry stage to the wet stage, crooked vision disorder increases. For example, the straight lines on the edge of a door or on a paper are perceived as if they are wavy. It hemorrhage occurs additionally, visual acuity suddenly weakens, and reading is no longer possible. A black spot is seen in the middle of the eye, and this spot covers everything that is directly looked at. At the stage of wound scar, a defect remains in the middle of the visual field. The remaining visual field is never affected by this disease. Thus, orientation inside the area is never lost and complete blindness does not occur.

The point with best visual acuity (macula) is evaluated best when the pupil is dilated. During examination, a microscope and a very powerful loupe are used as assitive tools. The physician holds these in front of the patient’s eye or uses a contact lens placed on the eye (see picture).

The physician sees the point with best visual acuity in a very magnified state and can determine even the most sensitive changes. A staining substance examination called fluorescein angiography is usually performed to evaluate hemorhhages at the point with best visual acuity. The physician gives an injection of a staining substance solution in the arm. This staining substance is transferred to the retina through blood flow.
While the staining substance is flowing through the vessels, a picture of the point with best visual acuity can be taken when the pupil is dilated. Weak blood circulation, leaking vessels and neovascularization can easily be determined with this method.

Currently, efficient treatment of macular degeneration related with aging is possible only in a limited number of cases. The aim of treatment is to blunt leaking vessels or newly formed vessels by fulgurating, and thus, stop the disease. This is possible with a traditional laser. Laser treatment is painless and only lasts for a few minutes.

One of the newly developed therapies is Photodynamic therapy (PDT). Here, the vessels below the retina are made sensitive to a certain laser wavelength using a special staining substance called Verteporfin. Verteporfin is injected into an arm vein shortly before giving laser beam. Unfortunately, Photodynamic therapy can be applied successfuly only in a limited number of patients who have a special type of wet macular degeneration.