Topcon Corporation

About: Topcon Corporation is a company organization based out in Capelle aan den IJssel, Netherlands. It is known for research contribution in the topics: Signal & Laser scanning. The organization has 463 authors who have published 597 publications receiving 7279 citations.

Macular choroidal thickness and volume in normal subjects measured by swept-source optical coherence tomography.

Abstract: PURPOSE. To study the choroidal thickness in healthy subjects by swept-source optical coherence tomography (SS-OCT) at longer wavelength. METHODS. The macular area of 31 eyes (31 healthy volunteers) was studied with an SS-OCT prototype system, which uses a tunable laser as a light source operated at 100,000 Hz A scan repetition rate in the 1-m wavelength region. Three-dimensional volumetric measurement comprised of 512 128 A scans was acquired in 0.8 second. From a series of OCT images, a chroidal thickness map of the macular area was created by manual segmentation. To evaluate interoperator reproducibility, the choroidal thickness in each section from 10 subjects was determined independently by two observers. RESULTS. SS-OCT at the 1-m wavelength region allowed visualization of the fine structure of the choroid as well as that of the retina. Mean choroidal thickness and volume in the macula area were, respectively, 191.5 74.2 m and 5.411 2.097 mm 3 . The mean choroidal thickness of the outer nasal area was significantly thinner than that of all other areas (P 0.05). The measurements by the two independent observers were significantly identical; the intraclass correlation coefficient in mean choroidal thickness was between 0.945 and 0.980 in each area. The macular choroidal thickness was significantly correlated with axial length after adjustment for age (P 0.001), and with age after adjustment for axial length (P 0.001). CONCLUSIONS. SS-OCT system at 1 m provides macular choroidal thickness maps and allows one to evaluate the choroidal thickness more accurately. (Invest Ophthalmol Vis Sci. 2011; 52:4971‐4978) DOI:10.1167/iovs.11-7729

Compensation of corneal horizontal/vertical astigmatism, lateral coma, and spherical aberration by internal optics of the eye.

Abstract: Both the anterior surface of the cornea and the internal optics (the posterior cornea, crystalline lens) contribute to the aberration of a wavefront passing through the eye. Artal, Guirao, Berrio, and Williams (2001) reported that the wavefront aberrations produced by the internal optics offset, or compensate for, the aberrations produced by the cornea to reduce ocular wavefront aberrations. We have investigated the wavefront aberrations of the cornea, internal optics, and complete eye on both the population and individual level to determine which aberrations are compensated and probable paths leading to that compensation. The corneal and ocular aberrations of 30 young subjects at relaxed accommodation were measured with the Topcon Wavefront Analyzer, which simultaneously measures refraction, corneal topography (videokeratoscope), and wavefront aberrations (Hartmann-Shack sensor). We found strong evidence for compensation of horizontal/vertical (H/V) astigmatism (Zernike term Z5) lateral coma (Z8) and spherical aberration (Z12). H/V astigmatism compensation is scaled for each individual, suggesting that it is actively determined by a fine-tuning process. Spherical aberration shows no individual compensation, suggesting that is a passive result of genetically determined physiology. Lateral coma shows individually scaled compensation, some of which may be attributable to eccentricity of the fovea.