Save Your Vision With the Amsler Grid
The Amsler Grid Test
Look at the grid below. Cover your right eye. Stare hard at the spot in the middle of the grid.
Ask yourself these questions:
- Can I see both the corners and sides of the square?
- Are any of the lines wavy?
- Are there any holes or missing areas of the grid?
Now, switch eyes. Cover your left eye, and focus on the dot while looking out of your right eye. Compare the results.
If you saw any distortions, wavy lines, missing elements or holes, your eye may have a significant visual abnormality.
What a Distortion May Mean
When I looked at the spot in the middle of the Amsler grid, using my left eye, I saw a slight distortion in the lower left quadrant.
I have previously been diagnosed with an abnormality of my left eye’s macula, known as a macular pucker or epiretinal membrane. The distortion could be from edema from my recent cataract surgery, or it may just be the pucker creating the distortion.
Although an epiretinal membrane usually afflicts those over 50, it is very possible for a younger person to get one! So, let's first discuss the epiretinal membrane.
How It Forms
A macular pucker or epiretinal membrane is scar tissue on the macula, which is the part of our retina responsible for central vision. It is the macula which enables us to read, drive a car, and recognize people’s faces.
The scar tissue that forms may be caused from trauma, retinal detachment, diabetes, or posterior vitreous detachment (PVD) – or it may have an unknown cause. It is believed that the tissue develops as a protective immune response. Cells begin to proliferate over the macula, and eventually you have a membrane that, on examination, looks like tissue paper or shiny cellophane. If the membrane is bad enough, it will create traction on the retina. On an OCT scan, you will clearly see the membrane pulling on the retina, just as if you had marionette strings being manipulated right above your retina.
Since a moderate to severe epiretinal membrane creates tension that pulls the retina out of shape, the patient frequently experiences blurry or distorted vision.
Many epiretinal membranes develop to a certain point, and no farther. The patient’s vision will probably not get any worse. But in about 25% of the cases, matters become more serious, and vision continues to deteriorate.
What Can be Done
An epiretinal membrane may be removed by doing a surgical procedure called an ERM peel, usually done along with a vitrectomy (removal of the vitreous humor). About 75% of patients experience improvement in their vision, going half-way to normal. For instance, if, prior to surgery, your vision is 20/70, and 20/20 is considered normal, your best surgical result after an ERM peel would give you about 20/45 in your operated eye.
Even if your epiretinal membrane is not significant enough to require surgery, you still need to see a retina specialist at regular intervals to check for a worsening condition.
The Amsler grid may also find another problem which is unrelated to epiretinal membranes: macular degeneration.
Age-related macular degeneration (called ARMD or AMD) is the leading cause of legal blindness in seniors over the age of 65. AMD can be responsible for life-altering changes in vision. People with AMD may have blind spots, difficulty with contrast sensitivity, difficulty distinguishing colors, and, more seriously, a complete loss of the central area of vision, which is 35% of our vision. The remaining 65% of our vision is peripheral vision, and they nearly always retain that.
Risk factors for AMD include smoking, family history, obesity, a high-fat diet, and possibly sleep apnea.
There are two types of AMD: wet and dry. The dry form (central geographic atrophy) is the most common, and is caused by a thinning and atrophy of the cells of the macula as deposits called drusen proliferate. Dry AMD may cause blind spots, but most people will not lose their central vision. However, about 10% will progress to the wet form of the disease.
In wet AMD, blood vessels under the macula begin to grow uncontrollably and leak blood and fluid into the retina. The abnormal blood vessels eventually scar, leading to loss of central vision.
Treatments for AMD
There is no mainstream, FDA-approved surgical treatment for AMD. Some of the available therapies include drugs, vitamin supplements, photodynamic therapy, and laser therapy.
Now You Know
Now you can see the value of the Amsler grid. The grid was created in 1945 by a Swiss ophthalmologist named Marc Amsler. It can help you discover two very troublesome visual abnormalities. I recommend doing the test once in a while.
And, if you find that you are seeing a distortion or any other abnormality in the Amsler grid while viewing the square with either eye, see an ophthalmologist right away.
Awesome Surgery - Peeling an ERM
- Macular degeneration: http://www.webmd.com/eye-health/macular-degeneration/macular-degeneration
- Research these conditions in helpful forums: http://www.medhelp.org