Age-Related Macular Degeneration - Diagnostic Tools
Last week we blogged about Age-Related Macular Degeneration (AMD) and reviewed the symptoms as well as who is at risk for this vision stealing disease. This week our blog is about tools doctors use to diagnose AMD as well as how they treat the different stages of AMD. The National Eye Institute provides a wealth of information.
The following briefly describes how doctors determine if AMD is present in their patients:
- Visual acuity test. This is a measurement of how well one sees at distances by using the eye chart.
- Dilated eye exam. Drops are placed in the patient’s eyes that cause the pupils to dilate. At that time the doctor can see better into the retina and optic nerve for signs of AMD or other eye disease.
- Amsler grid. This is a grid printed on paper or a magnet (that can be placed on your refrigerator) and is given to the patient to take home as a tool to track quality of vision at home. Since AMD affects the central vision, the grid will show symptoms of AMD if the center of the grid appears wavy or absent.
- Fluorescein angiogram. The ophthalmologist performs this test. A fluorescent dye is injected into patient’s arm and pictures are taken as the dye passes through the blood vessels in the eye. This test can allow the doctor to see if there are any leaking blood vessels.
- Optical Coherence Tomography (OCT). Instead of using ultrasound which uses sound waves to capture images, with an OCT light waves are used and this is a painless, easy test. The patient puts their chin on a chin rest (after eyes are dilated) and the patient must be still for only a few seconds. A light beam captures pictures that can be printed.
What does the doctor look for – beneath the retina - when using these diagnostic tests?
The presence of yellow deposits called drusen can be a telltale sign of AMD, depending on the amount. Small drusen are normal to see but medium to large may be a sign of AMD.
Pigmentary changes that occur may be a sign. Dark clumps of pigment and eventually less pigment give the doctor more clues.
NEI tells us that it could take about 10 years to develop late AMD but not everyone with AMD will advance to the late stage. We are also advised that if you have AMD in one eye, you may still function well for driving, reading and other fine detailed activities with one healthy eye. As in all things medical, the sooner one is diagnosed the better the outcome due to the opportunity for early treatment.
In another blog we will cover the stages of AMD – Early, Intermediate and Late, plus Advanced as well as treatments used.
The information covered in this blog is credited to the following link: https://nei.nih.gov/health/maculardegen/armd_facts