Imaging of the lens capsule with an ultrahigh-resolution spectral optical coherence tomography prototype based on a femtosecond laser

Abstract

Aim: To demonstrate the applicability of ultrahigh-speed, ultrahigh-resolution spectral optical coherence tomography (SOCT) to cross-sectional imaging of the capsular bag in vivo.

Methods: The ultrahigh-speed and ultrahigh-resolution SOCT prototype was designed and constructed at Nicolaus Copernicus University (Torun, Poland). To obtain an ultrahigh speed up to 100,000 lines/s a new spectrometer with fast CMOS line-scan camera was built. A femtosecond laser with a central wavelength of 780 nm and Deltalambda=160 nm enabled imaging with an axial resolution of 2.3 microm and lateral resolution of 10 microm in tissue. Lens capsules of two healthy eyes were examined with the aid of the instrument using two- and three-dimensional scanning protocols.

Results: The prototype provided ultrahigh-resolution tomograms composed of 8000 A-scans with an acquisition time of 0.16 s. The quality was sufficient to evaluate the capsular bag and to estimate its thickness. It was possible to visualise a separate layer of lens epithelium, to the authors' knowledge the first such visualisation. Three-dimensional data were used to produce lens-capsule thickness maps.

Conclusions: Ultrahigh-resolution, ultrahigh-speed SOCT based on a femtosecond laser allows two- and three-dimensional evaluation of a capsular bag and lens epithelium. The instrument provides new information of scientific and clinical value.