459 - March 2022

MARCH 2022 | The Surgical Technologist | 115 Drusen are yellow-colored deposits that accumulate between the retinal pigment epithelium and Bruch’s mem- brane, the innermost layer of the choroid, that consist of lipids and proteins. 9 Drusen occur normally with age and are not known to cause AMD, but they are considered the primary sign of AMD. 7,9 Usually they are incidentally dis- covered during a normal eye exam because they don’t pro- duce symptoms. 9 A significant number of large drusen is usually an early sign of geographic AMD. • Early AMD is indicated by the presence of medium- sized drusen that have an approximate diameter com- parable to a human hair. 2 Patients with early AMD usually do not have vision loss. Not all patients diag- nosed with early AMD will deteriorate and develop late AMD. For patients who have early AMD in one eye, but no signs of AMD in the contralateral eye, approximately 5% develop advanced AMD after 10 years. 3 For patients who have early AMD in both eyes, approximately 14% develop late AMD in at least one eye after 10 years. 3 • Intermediate AMD is diagnosed by the presence of large drusen with or without pigment changes in the retina. 3 These changes, just like those associated with the early stage, are only detected during an eye examination. Intermediate AMD can cause some vision loss, but most patients do not exhibit symptoms. • Late AMD is characterized by drusen and vision loss because of damage to the macula. There are two types of late AMD – geographic and neovascular. Patients can develop both conditions in the same eye and either can appear first. 3 – Geographic AMD, also called dry AMD, is char- acterized by the loss of retinal pigment epithelium (RPE) and choroid in the macula lutea causing the gradual loss of cones and vision. 3,7 Geographic AMD occurs more slowly as compared to neovas- cular AMD. It is the most common type accounting for 90% of diagnosed cases. 4 – Neovascular AMD, also called wet AMD, is caused by the abnormal growth of blood vessels from the choroid into the normally avascular RPE. 7 The ves- sels often leak blood that causes the macula lutea to swell and become damaged. The damage can be rapid and severe. Wet AMD accounts for approxi- mately 10% of cases but results in 90% of patients being legally blind. 5 D E T E C T I O N O F A M D A N D D R U S I N Symptoms are easy to misinterpret or overlook if only one eye is affected. Often patients who have a disease that is slowly affecting one eye do not seek care until their activi- ties of daily living are affected. The healthy eye will adjust and make up for what the affected eye is lacking causing the diagnosis to occur once the disease has progressed enough to result in irreversible vision loss. An earlier indication of macular degeneration would be the need for brighter light- ing and having difficulty adjusting to lower light settings. However, those symptoms are commonly overlooked as having vision trouble. Most symptoms that lead to a diagno- sis are blurriness, distortion of straight lines, seeing blurry spots, and worst of all unable to recognize faces. The only exam that will detect AMD is a dilated eye exam that may include the following. • Amsler grid: The changes in the patient’s central vision will cause the grid lines to appear wavy or disappear (see Figure 2). 3 • Dilated eye exam: Allows the physician to view the retina and optic nerve for signs of AMD. • Fluorescein angiogram: Fluorescein dye is injected into a vein usually on the medial side of the elbow and the images are taken. This allows the physician to identify if there are vessels leaking blood that is often a sign of late AMD. Figure 2: (A) Normal view of Amsler grid, (B) View of grid by patient with AMD. A B