Long scan depth optical coherence tomography on imaging accommodation: impact of enhanced axial resolution, signal-to-noise ratio and speed

Abstract

SLD: superluminescent diode, OI: isolator, FC: fiber coupler, PC: polarization controller, CL1–3: collimating lenses, DC: dispersion compensator, L1–4: objective lenses, M1–2: refractive mirror, GM: galvanometer mirror, LCD: liquid-crystal display, DG: diffraction grating, CA: camera (CCD with 2048 pixels for system 1, CCD with 4096 pixels for system 2 and CMOS with 4096 pixels for system 3) The three systems had a similar spectrometer design composed of four parts: a collimating lens (f = 50 mm, OZ Optics, Ottawa, Canada), a 1800 lines/mm volume holography transmission grating, an image enlargement lens with a focal length of 240 mm (f = 240 mm, Schneider Optics, Hauppauge, NY), and a line array camera. In this case, the anterior segment length from the anterior surface of the cornea to the posterior surface of the IOL in the implanted patient was shorter than the phakic eye because the IOL was thin. [...]the distance between the two reference mirrors was decreased to place the zero-delay line of arm 2 near the posterior polar of the IOL. The central Bowman’s layer in the magnified images was presented in systems 2 and 3 (Fig. 5b1 and c1), whereas the boundary of the corneal components in the image from system 1 was blurred (Fig. 5a1). [...]the boundaries of the Bowman’s layer in system 1 was barely identified as the peaks in the reflectivity profiles but was easily distinguished in systems 2 and 3 (Fig. 5a4-a4, peak a and b) [35]. [...]as the most important component, the crystalline lens reshapes its surface in a complex form with tilting and/or decentration. [...]three-dimensional scan patterns are required, which the OCT based on CMOS camera can perform [10].