Improving on old technologies
“The idea of contrast function is not new, as with the familiar Pelli-Robson contrast testing,” said Dr. Miller, assistant professor of ophthalmology, Harvard Medical School; director of retinal imaging, Massachusetts Eye and Ear, Boston.
The disadvantage of Pelli-Robson contrast testing is that the measurement is done at a single spatial frequency that determines the most-faint letter that can be seen at one type size. Similarly, with traditional Snellen or Sloan letter acuity, clinicians are measuring at one high-contrast frequency as the optotypes get progressively smaller.
With the new device, clinicians can measure multiple spatial frequencies in multiple contrast frequencies and obtain “the world of vision,” i.e., the area under the curve, that the patient can see.
“This technology offers new ways to detect the changes in visual recovery after retinal reattachment.” Dr. Miller said. “The initially large optotypes that are presented to the patient become progressively faint until they are barely visible, which is analogous to Pelli-Robson contrast testing.”