Abstract
Purpose :
This abstract focuses on the technical aspects and capabilities of the novel cell-resolution anterior eye imaging technology, Optical transmission tomography (OTT). This technology will be presented for the first time at ARVO imaging in the eye 2024.
Methods :
In vivo ophthalmic OTT was inspired by the two scientific directions: 1) OTT in ex vivo microscopy (https://doi.org/10.1364/BOE.453586, https://doi.org/10.1364/BOE.494585) as well as the 2) Asymmetric retroillumination microscopy (https://doi.org/10.1364/BOE.391815). OTT relies on the illumination of the fundus of the eye (well-known red eye effect in photography), which illuminate the anterior eye from behind in a common path interferometric configuration. The interferometric contrast occurs between the light immerging from the fundus and the forward-scattered light from the structure thanks to Gouy phase shift. The interferometric behaviour of light allows to reject the out-of-focus light to improve the contrast. The majority of imaging methods are “reflection” based, however, OTT relies on a “transmission” configuration (Fig. 1). Forward-scattered light surpasses back-scattered in intensity for ocular structures, offering a non-contact alternative to corneal confocal microscopy (the state-of-the-art high-resolution optical sectioning method).
Results :
OTT revealed cell-resolution structures across the anterior main layers of the eye (Fig. 2): corneal epithelium (superficial, wing, basal cells), sub-basal nerve plexus, stroma (nerves, keratocyte cells), endothelium cell mosaics, and crystalline lens (epithelium, sutures, fibers). Images were captured at 1 µm resolution over a 2.5 mm x 1.5 mm field of view (FOV), 25x larger than confocal and specular microscopies, and 3x larger than advanced systems like Curved-field OCT. A future FOV expansion to 4 mm x 2.5 mm is possible with a resolution trade-off. The expanded FOV improves cell counts and anterior eye evaluations, aiding cataract surgery decisions, reducing corneal failures, and helping detect dry eye and assess refractive surgery risks.
Conclusions :
Optical transmission tomography offers a novel imaging approach for the anterior eye, bridging micro and macro perspectives. This cell-resolution, global-scale view aids diagnosis, follow-up, and comprehension of complex corneal and lenticular conditions.
This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.