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Portable ETDRS chart offers advantages over standard chart
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PHILADELPHIA — A pocket-sized ETDRS chart has the advantage of the high reproducibility of the standard ETDRS chart without the bulkiness, a speaker said here.
While the Snellen chart is the most widely used eye chart, limitations apply, such as limited reproducibility, fluctuating background illumination, different number of letters on each line, and letters with different levels of difficulty to read.
"The ETDRS chart is plain and simple, a much more reliable eye chart," Francis Char DeCroos, MD, said at the Wills Eye Institute Annual Conference.
Francis Char DeCroos
The ETDRS chart contains standardized illumination, five letters on each line, letters of equal difficulty to read, and a standard geometric progression for each line; however, it is bulky and requires a 4-m lane, DeCroos said.
DeCroos discussed the Retinal Acuity Meter ETDRS (RAM-ETDRS) chart, a miniaturized version of the larger chart. The correlation between the RAM-ETDRS chart and the standard ETDRS chart is being evaluated.
In a multicenter prospective study to validate the device, 36 eyes of 18 patients are being studied, with a goal to enroll 130 eyes of 65 patients. The preliminary data are encouraging, DeCroos said.
Disclosure: DeCroos has no relevant financial disclosures.