The researchers showed that the new optical coherence tomography (OCT) imaging system can not only image both the front and the back of the eye, but can also image the interfaces of the eye's vitreous gel with the retina and lens with unprecedented detail.
This new imaging capability could allow scientists to better understand how the vitreous gel that fills the eye interacts with the retina and why it can sometimes become detached with aging. The study was published in the journal Optica
Increasing imaging depth
The new system is based on OCT, which is commonly used to acquire very detailed, cross-sectional ophthalmology images. Most clinical instruments are limited to imaging depths of 2 to 3 millimeters, and it is difficult to switch between imaging the front and back portions of the eye because the eye is composed of elements that bend the light to focus it onto the retina.
To overcome these challenges, the researchers used an electrically tunable lens to build an OCT instrument that could focus light in a way that enabled whole-eye imaging. Unlike standard glass or plastic lenses, which have fixed parameters, the optical properties of an electrically tunable lens can be dynamically controlled using an electric current.
The OCT system also incorporated a newly commercialized swept light source, a laser that continuously changes wavelength very rapidly. The wavelength-tunable laser improves the resolution and speed of OCT compared to systems that use other light sources. The researchers integrated high-speed electronics to achieve the imaging depth necessary to enable whole eye imaging.
The researchers used their new system to measure the anatomical characteristics of the eyes of seven healthy people. Measurements calculated using images from the new system correlated well with those obtained with an ocular biometer, the standard clinical device used today.
The researchers are now working to optimize the instrument for imaging of the entire vitreous gel, not just where it interfaces with the lens and retina. The vitreous gel has not been studied intensively and is difficult to image because it is highly transparent.
The ability to image the entire vitreous could allow OCT to be used to guide procedures that involve the removal of the vitreous gel from the eye, which is sometimes done to repair retinal detachment. Although the laboratory version of the set-up is ready to use, further steps will be taken to translate the technology to the clinic.
The scientists are focused on optimizing the scan areas and developing processing tools for automatic measurement of the dimensions of the eye. These improvements will enable advanced studies of the proposed scan regimes on a group of patients with different types of opacification in the eye.