The Eye Chart Challenge
Many of you probably know the feeling – getting ready for your periodic ophthalmologist visit. You think your vision is okay or at least not worse and then comes the eye chart test! And your vision has deteriorated – damn it. How come I didn’t ‘see ‘ that coming?
At my doctor’s office the eye chart test is given by a skilled technical staff member but it is the first thing the ophthalmologist looks at; even before examining my eyes with the thousands of dollars worth of high-tech equipment. And this test appears to be the basis for determining whether things are good, bad or worse.
This last appointment really bothered me so I’ve researched Eye Charts and have discovered there are several different kinds. Wikipedia gives some good information and I’ve visited several websites as well. Snellen, logMar, Landolt C and Lea are versions of Eye Charts – who knew there were so many types; some designed for one type of problem, some for another?
All eye charts are highly complex, made up of optotypes or test symbols, have a particular simple geometry, and some may be useful in measuring contrast, motion and color. There are even eye charts for non-readers and children. I’ve had mac degen for 19 years and this is the first time I’ve realized the impact of the Eye Chart.
Another good question is what other type of visual acuity tests are used? There are many that do not require the use of high-tech machinery but do a good job indicating change in vision. The Jaeger hand-held card is one that can help judge reading distance.
Does the optometrist use one type and the ophthalmologist another? Perhaps the low vision specialist uses another. Has anyone explained the limitations of an Eye Chart test? Have you ever asked?
Has something like this happened to you? Has your eye care team explained what and why they use a specific Eye Chart? I’d like to hear what you have to say.