Scientists have used a technique normally used in astronomy to see living cells in the human retina for the first time. Donald Miller and Larry Thibos of Indiana University believe that instruments that use “adaptive optics” could help in the early diagnosis of retinal diseases (Donald Miller and Larry Thibos Indiana University press release)
Astronomers developed adaptive optics to overcome the blurring in their images caused by turbulence in the Earth’s atmosphere. In adaptive optics, atmospheric distortions in the light from a “reference beacon” are analysed by a sensor, which then sends electronic signals to a “deformable” mirror that changes its shape to correct for the distortions. The mirror’s shape can change several hundred times a second, which ultimately results in a sharper image of the object observed.
Miller and Thibos applied this principle to observations of the human eye: an optical instrument takes the place of the telescope, cells on the retina play the role of stars, while the inside of the eye distorts the image just like the turbulence in the Earth’s atmosphere. The reference beacon is a laser spot focused on the retina.
Thibos created an “ocular aberrometer” that measures the deviation in optical wavefronts reflected by the retina using a “Shack-Hartmann” sensor, and Miller developed technology that corrects these deviations. Combined with a retina camera, the researchers will be able to make high-resolution, non-invasive observations of cells at the back of the eye.
The scientists hope that their instrumentation will help doctors to diagnose retinal disease before actual symptoms appear.
